August 2011: Magnesium supplement improves insulin sensitivity
A new study has found that taking a magnesium supplement improves insulin sensitivity, the underlying problem in PCOS and type 2 diabetes.
A number of studies have found that magnesium plays a role in glucose and insulin metabolism and previous research has found a link between magnesium intake and risk of type 2 diabetes. In this study, researchers from the Justus-Liebig-University in Germany wanted to see if taking a magnesium supplement would improve insulin sensitivity in overweight individuals who were insulin resistant but didn’t have diabetes. Insulin resistance means that insulin is unable to work effectively in the body to reduce blood glucose levels and is the underlying problem in type 2 diabetes. Individuals who are insulin resistant are therefore at risk of developing diabetes.
They studied 32 overweight subjects aged between 30 and 70 years who had normal magnesium levels. They were randomised to two groups – one which took a magnesium supplement (365mg of magnesium aspartate hydrochloride) and the other a placebo. The study lasted for 6 months.
The results are published in the March issue of Diabetes, Obesity and Metabolism, showing that the group taking magnesium had greater improvements in fasting blood glucose levels and a number of measures of insulin sensitivity compared to the placebo group. Blood pressure and cholesterol levels didn’t change significantly.
The researchers point out that the improvements in insulin sensitivity seen in their study were similar to that of a previous study with the diabetes medication metformin. They also highlight the fact that these results were seen despite the fact that the study subjects had normal magnesium levels to start with – many of the previous studies looking at the benefits of magnesium have been in individuals with low magnesium levels.
They study supports the importance of a good dietary intake of magnesium, particularly for those at risk of type 2 diabetes, and suggests that supplementing with magnesium may be beneficial even in those who are not deficient in this mineral. Good food sources include wholegrains, nuts, seeds (particularly pumpkin seeds), legumes, green leafy vegetables and dark chocolate.
Mooren et al. Oral magnesium supplementation reduces insulin resistance in non-diabetic subjects - a double-blind, placebo-controlled, randomized trial. Diabetes Obes Metab. 2011 Mar;13(3):281-4.
July 2011: Cereal fibre, not protein, improves insulin sensitivity
A new German study suggests that a high protein diet is not the answer to reducing insulin resistance, the underlying problem in PCOS and type 2 diabetes.
Researchers from the Heinrich-Heine University Düsseldorf in Germany compared the effects of a high protein diet, a high cereal fibre diet and a third diet with moderate increases in both protein and cereal fibres. All diets contained the same amount of energy, or kilojoules. They studied 111 overweight adults with features of the metabolic syndrome (which include raised blood glucose levels, triglycerides and blood pressure, low ‘good’ HDL cholesterol and carrying weight around the middle) and 84 of these subjects completed the study, They were randomly allocated to one of four groups (the three diet groups mentioned above and a control group which were given basic healthy eating advice). All participants were provided with a dietary supplement to take twice/day, to help them to achieve their particular dietary targets.
During the first 6 weeks the high protein (HP) group consumed 28% of their energy from protein compared to only 17% in the control and high cereal fibre (HCF) groups and 23% in the mixed group. The fibre content of the diets during this initial phase was 43g per day in the HCF group, 13g in the HP group,14g in the control group and 26g in the mixed group. For the following 12 weeks the protein intake in the HP group and the fibre content of the HCF group were slightly lower (26% instead of 28% and 41g instead of 43g).
Published ahead of print on June 1st in the American Journal of Clinical Nutrition, the results show that the diets had significantly different effects in insulin sensitivity. After 6 weeks on the HCF diet insulin sensitivity was 25% higher compared to the HP diet. Insulin sensitivity is a measure of how well insulin works in the body – insulin resistance, or poor insulin sensitivity, is the underlying problem in type 2 diabetes. The difference between the groups had lessened by 18 weeks which the researchers say was most likely explained by the fact that many participants in the HP diet were not sticking as closely to their diet and had reduced their protein intake over time. However the improvement in insulin sensitivity in the HCF group was sustained over the 18 weeks, suggesting that a high cereal fibre diet may have prolonged beneficial effects on insulin sensitivity.
The researchers found that the higher protein intake tended to increase the levels of an enzyme called serine-kinase-6-1 (S6K1) which is known to induce insulin resistance. Interestingly the mixed diet didn’t show the same detrimental effects on insulin sensitivity despite a higher protein intake, which the researchers say may be explained by the fact that the higher intake of cereal fibre in this group interfered with the absorption of protein. They suggest that this may be one explanation for the relationship between higher fibre diets and reduced diabetes risk which has been demonstrated in many previous studies.
Weickert et al. Effects of supplemented isoenergetic diets differing in cereal fiber and protein content on insulin sensitivity in overweight humans. Am J Clin Nutr. 2011 Jun 1. [Epub ahead of print]
June 2011: Excess egg consumption increases GDM risk
Eating one or more eggs each day before or during pregnancy may increase the chances of developing gestational diabetes (GDM) according to a new study published in the March issue of the American Journal of Epidemiology.
Researchers from the Center for Perinatal Studies at the Swedish Medical Center in Seattle, in the US looked at the findings of two studies which investigated the relationship between egg consumption prior to or during early pregnancy and GDM risk.
The first study of more than 3100 women found that women who ate 10 or more eggs per week had more than 2.5 times the risk of developing GDM compared to those who didn’t eat eggs. Those who at 7 or more eggs per week increased their risk 1.8 fold compared to those who ate less than 7 eggs per week.
The second study, a case-control study, compared 185 women who developed GDM with 411 women who didn’t develop diabetes (controls). Similar to the first study, they found that the odds of developing GDM was 2.7 times higher in those who ate 7 or more eggs per week compared to those who ate less than 7 per week. In both cases, the findings were independent of other factors which may affect diabetes risk.
Both studies also found that the risk of GDM was higher in those who consumed more cholesterol in their diet. In the first study the risk was 2.4 fold higher in those with the highest cholesterol intakes (294mg per day or more) compared to those with the lowest intakes (less than 151mg/day); in the second study the risk was 2.9 times higher. A medium egg contains around 200mg of cholesterol.
These studies support the findings of previous research showing a link between high egg intake and type 2 diabetes, and between cholesterol intakes and both gestational diabetes and type 2 diabetes. The researchers suggest that further studies are needed to explore the mechanisms behind this increased risk.
In the meantime, while eggs are a convenient and nutritious food, the study suggests that, like most things, they should be consumed in moderation and alternated with other protein foods, particularly if you are trying to conceive.
Qiu et al. Risk of gestational diabetes mellitus in relation to maternal egg and cholesterol intake.Am J Epidemiol. 2011 Mar 15;173(6):649-58. Epub 2011 Feb 15.
May 2011: Vegetarian diet improves insulin sensitivity
A vegetarian diet improves insulin sensitivity and abdominal fat more than a conventional diabetic diet according to a new study published in the May issue of Diabetic Medicine.
Researchers from the 1st Faculty of Medicine Institute of Endocrinology in Prague in the Czech Republic studied 74 subjects with type 2 diabetes who were randomised to either a vegetarian diet or control group who followed a conventional diabetic diet. Both groups consumed the same amount of energy (calories or kilojoules) which was restricted in order to achieve weight loss. The study lasted 24 weeks and all meals were provided to subjects. During the second 12 weeks of the study the participants were also prescribed an individualised exercise program, prior to this they were asked not to alter their exercise habits.
The vegetarian diet consisted of vegetables, grains, legumes, fruits and nuts, with 60% of energy from carbohydrates, 15% from protein and 25% from fat. The only animal product allowed was one serving of low-fat yogurt each day. The conventional diabetic diet was provided according to the dietary guidelines of the Diabetes and Nutrition Study Group (DNSG) of the European Association for the Study of Diabetes (EASD). It contained 50% of total energy from carbohydrates, 20% protein, less than 30% Fat (with less than 7% saturated fat and less than 200 mg of cholesterol per day). Alcohol was limited in both groups to one standard drink per day for women and two per day for men.
The researchers found that after 24 weeks, 43% of those in the vegetarian diet group had reduced their diabetes medication compared to only 5% of those in the control group. The vegetarian dieters lost most weight - 6.2kg versus 2.3kg, and also had greater reductions in body fat, particularly visceral fat, or fat stored around the middle. Insulin sensitivity improved by 30% in the vegetarian diet group compared to 20% in the control group, suggesting that the vegetarian diet was better at improving how insulin works in the body – insulin resistance or poor insulin sensitivity, is the underlying problem in type 2 diabetes and PCOS.
Markers of oxidative stress were also improved to a greater extent on the vegetarian diet and the researchers suggest that this may be the main contributor to the improvement in insulin resistance. Oxidation causes damage to the cells in our body and is believed to be an important factor in the development of a number of chronic as well as playing a role in ageing. Interestingly, the addition of exercise increased the differences between the groups – in other words the improved outcomes in the vegetarian diet were even greater when they were also exercising.
Kahleova et al. Vegetarian diet improves insulin resistance and oxidative stress markers more than conventional diet in subjects with Type 2 diabetes. Diabet Med. 2011 May;28(5):549-59. doi: 10.1111/j.1464-5491.2010.03209.x.
April 2011: Vitamin D levels important in gestational diabetes
A new Australian study has found that low vitamin D levels are linked with poorer blood glucose control in women with gestational diabetes (diabetes in pregnancy).
Researchers from Westmead Hospital in Sydney studied almost 150 women attending the gestational diabetes (GDM) clinic at Westmead Hospital from February 2007 to February 2008, who were on average around 35 weeks of pregnancy. They had blood tests during the third trimester of pregnancy to measure HbA1c (which reflects average blood glucose control over the previous 2-3 months) and vitamin D levels. GDM was diagnosed using an oral glucose tolerance test (OGTT).
The results are published in the April 4 issue of the Medical Journal of Australia showing that 41% of the women had low levels of vitamin D (50nmol/L or below). Lower levels were seen in women from Middle Eastern and Indian backgrounds, as well as women who performed home duties compared to those in paid employment. Not surprisingly, vitamin D levels were much higher in summer than during other seasons. Weight did not appear to affect vitamin D levels.
Women with lower vitamin D levels were found to have higher blood glucose levels – both fasting and 2 hour glucose levels during the oral glucose tolerance test, and HbA1c levels. Low vitamin D levels were associated with a higher HbA1c, independent of other factors.
The authors suggest randomised trials are needed to determine whether vitamin D plays a role in blood glucose control in gestational diabetes. In the meantime, considering the high prevalence of vitamin D deficiency they found in the study, and the fact that low vitamin D levels in pregnancy can have other adverse effects for the unborn baby, they recommend routine testing of vitamin D for all pregnant women, either alongside or prior to screening for GDM.
Lau et al. Serum 25-hydroxyvitamin D and glycated haemoglobin levels in women with gestational diabetes mellitus. Med J Aust. 2011 Apr 4;194(7):334-7.
March 2011: More evidence for link between pregnancy glucose and childhood obesity
A new study has found that children of women who did not have diabetes or develop gestational diabetes but who had slightly elevated glucose levels in pregnancy, were more likely to be overweight by age 3.
It is now well established that children of women with pre-existing diabetes or gestational diabetes (diabetes which develops in pregnancy) are more likely to develop obesity and type 2 diabetes later in life, as a result of exposure to excess glucose in utero. In the current study researchers looked a the relationship between a child’s BMI (body mass index) at age 3 years and their mothers blood glucose level (measured during a glucose challenge test at around 27 weeks gestation to screen for gestational diabetes) in women without pre-existing or gestational diabetes. They studied 263 mother- child pairs.
They found that at 3 years of age, 21% of children were overweight and 5% obese. After controlling for mum’s pre-pregnancy weight, children whose mothers had a glucose level of 7.2mmol/L or more were more than twice as likely to be overweight or obese compared to those with a glucose level under 5.6mmol/L. The current cut-off for the diagnosis of gestational diabetes is 7.8mmol/L.
The researchers suggest that even in the absence of diagnosed diabetes or gestational diabetes, children who are exposed to higher glucose levels in pregnancy are more likely to develop weight problems later in life. They suggest that this is a modifiable factor that could reduce future obesity risks for a child and suggest that women with raised glucose levels, even if they don’t meet the current criteria for gestational diabetes, may need intervention to reduce their child’s exposure to excess glucose during pregnancy.
Deierlein et al. The Association Between Maternal Glucose Concentration and Child BMI at Age 3 Years. Diabetes Care 2011; 34: 480-484.
February 2011: Weight gain in pregnancy.....not too little and not too much
Researchers from the EDEN study group looked at the relationship between pre-pregnancy weight and weight gain during pregnancy with pregnancy and birth outcomes, both in women with and without gestational diabetes (diabetes in pregnancy) and high blood pressure. They found that being overweight before falling pregnant (ie having a high BMI or body mass index) increased the risk of having a large baby by more than 3-fold, while gaining a larger amount of weight during pregnancy increased the risk 1.6 times. However when they excluded women with gestational diabetes and high blood pressure, the risks were closer - 2.6 times higher for the overweight women and 2.1 times higher for those who gained more weight during their pregnancy.
On the other hand, women who had a low weight gain during pregnancy had more than double the risk of having a pre-term baby and this was increased to 2.7 fold after accounting for high blood pressure and gestational diabetes.
The researchers comment that these results reinforce the association between low maternal weight gain during pregnancy and premature birth, and high weight gain with risk of having a large baby. They also highlight their findings showing a link between weight gain in pregnancy and the risk of large babies in women without gestational diabetes or high blood pressure, suggesting that avoiding excess weight gain is important even for women without these risk factors. However they comment that this must be monitored closely to avoid low weight gain and the associated risk of pre-term delivery. For women who are overweight, losing weight prior to falling pregnant can reduce these risks.
Heude et al. Pre-Pregnancy Body Mass Index and Weight Gain During Pregnancy: Relations with Gestational Diabetes and Hypertension, and Birth Outcomes. Matern Child Health J. 2011 Jan 22. [Epub ahead of print]
January 2011: High protein no better than high carb diets for type 2 diabetes
A high protein diet is no better than a higher carbohydrate diet for improving glucose control, weight loss and heart disease risk factors in people with type 2 diabetes according to a new Australian study.
Dietary changes and weight loss are the cornerstone of management of type 2 diabetes but there is still debate over the optimal composition of the diet, particularly when it comes to protein and carbohydrate intakes. So researchers from the RMIT University in Melbourne set out to compare the effects of two low fat diets, one higher in protein and one higher in carbohydrate, in individuals with type 2 diabetes.
They studied almost 100 subject with type 2 diabetes who were randomly allocated to one of the groups – both diets were low in fat (30% of total energy) but differed in the proportions of protein and carbohydrate – the high protein diet aimed for 30% of energy from protein and 40% from carbohydrate while the higher carb diet aimed for 55% of energy from carbohydrate and 15% from protein. Both diets recommended low GI carbs. Each participant was provided with dietary advice by a dietitian including menu plans and food lists.
Both groups had similar improvements in HbA1c levels (a measure of average glucose control over the past 2-3 months), weight loss and blood fats (cholesterol and triglyceride levels). There was also no difference between the groups in blood pressure, kidney function or calcium losses. It is though that the latter could potentially worsen on a higher protein diet but this was not seen in the current study.
They also measured dietary self-management (participants were asked to rate their own ability to follow their prescribed diet) and found that that this was a significant predictor of success. In fact those with the highest self-management score at 1 year lost an average of 5.5 kg of body weight and reduced their HbA1c levels by 0.87% whereas participants with the lowest self-management score had little change in weight or HbA1c (reduced by 0.03kg and 0.03%, respectively).
The researchers conclude that energy restriction and weight loss are the best predictors of improved blood glucose control in type 2 diabetes, not dietary composition, and suggest that future studies should focus on developing skills to improve dietary adherence and self-management rather than modifying dietary composition.
Larsen et al. The effect of high-protein, low-carbohydrate diets in the treatment of type 2 diabetes: a 12 month randomised controlled trial. Diabetologia. 2011 Jan 20. [Epub ahead of print]
December 2010: Pre-pregnancy exercise reduces gestational diabetes risk
Women who are more active before falling pregnant or early in their pregnancy are less likely to develop gestational diabetes according to comprehensive review of current research.
Gestational diabetes (GDM) is diabetes which first presents during pregnancy and resolves after the pregnancy, although women with GDM are at increased risk of developing type 2 diabetes in later life. It is recommended that all women are screened for GDM at 24-28 weeks gestation, or earlier if they are at high risk (which includes women with PCOS). Blood glucose levels must be kept well controlled during pregnancy (with diet, exercise, and insulin if required) to reduce the risk of complications to both mother and baby.
Researchers from the Harvard School of Public Health conducted a systematic review of studies looking at the relationship between physical activity and the development of GDM. They found 12 studies, 7 which assessed pre-pregnancy activity (in a total of almost 35 000 women) and 5 which looked at activity levels in early pregnancy (in a total of just over 4400 women).Their finding are published in the December issue of Diabetes Care showing that compared to women with the lowest physical activity levels before pregnancy, those who were most active had a 55% lower risk of developing GDM. When it came to exercise in early pregnancy, the most active women were 24% less likely to develop GDM compared to those who did little activity.
The researchers conclude that promoting physical activity among women of reproductive age may be one way to reduce the risk of GDM and the complications for children born to these women. They also recommend that further research is needed to determine whether beginning an exercise routine in early pregnancy can reduce the risk in women who were previously inactive, and to see if there is an additive effect of being active both before and during early pregnancy.
Tobias et al. Physical activity before and during pregnancy and risk of gestational diabetes mellitus: a meta-analysis. Diabetes Care. 2010 Sep 27. [Epub ahead of print]
December 2010: Low GI diet plus exercise the key to type 2 diabetes prevention
A lifestyle program involving exercise, diet and weight loss may delay the onset of type 2 diabetes when the diet has a high glycemic index (GI), but has the potential to actually prevent diabetes if a low GI diet is followed. That’s the findings of a new study published in the November issue of the American Journal of Clinical Nutrition.
The researchers studied 22 older, obese individuals with pre-diabetes. They took part in a 12 week exercise training program and at the same time were randomly assigned to follow either a low GI or high GI diet. Each exercise session was supervised and the program consisted of walking on a treadmill or riding an exercise bike for 1 hour per day on 5 days per week, working at 85% of their maximum heart rate. All food and beverages were provided to participants on a daily basis. The composition of the diets was similar, apart from the GI which was 40 in the low GI group and 80 in the high GI group.
The researchers report that both groups lost similar amounts of weight and had similar improvements in insulin sensitivity. However only the low GI diet group had reductions in insulin secretion after being given a glucose load, while insulin secretion actually increased on the high GI diet.
The development of type 2 diabetes starts insulin resistance, when the body’s insulin is unable to work properly. Initially, the body makes extra insulin to overcome this resistance (this is called hyperinsulinemia, or high levels of insulin in the blood), so blood glucose levels remain normal. But if nothing is done to reduce the extra workload of the body’s insulin producing cells (beta cells), eventually they can’t keep up and blood glucose levels start to rise. At this stage the beta cells just can’t keep up making enough insulin to overcome the resistance of the muscles and cells to its action. As blood glucose levels rise, the individual progresses from having insulin resistance to impaired glucose tolerance/impaired fasting glucose (known as pre-diabetes) to diabetes itself.
This means that preventing diabetes requires both an improvement in insulin resistance (making the muscles and cells more sensitive to insulin) and reducing the stress on the beta cells to produce insulin. This study found that while both diets, in combination with exercise and weight loss, improved insulin sensitivity, that only the low GI diet helped in reducing the workload on the insulin-producing beta cells. The researchers suggest that this may be the optimal lifestyle treatment for prevention of type 2 diabetes.
Solomon et al. A low–glycemic index diet combined with exercise reduces insulin resistance, postprandial hyperinsulinemia, and glucose-dependent insulinotropic polypeptide responses in obese, prediabetic humans. Am J Clin Nutr 2010;92:1359–68.
November 2010: Lack of sleep reduces fat loss
If you want to lose body fat you should not only concentrate on your diet but also make sure you are getting enough sleep according to the findings of a new US study.
Researchers studied ten overweight but otherwise healthy, non-smoking adults aged 35 to 49 years. They took part in two 2 week experiments during which time they lived in the research centre where their food intake, exercise and sleep was monitored. In both experimental periods, they were provided with a diet moderately restricted in energy to produce weight loss. They were only able to eat and drink what was provided. In one experimental period they were allowed to sleep for 8.5 hours per night and in the other period sleep was restricted to only 5.5 hours per night. They were randomly assigned to the short or long sleep period first and then took part in the other experiment after a minimum of at least 3 months. .
Despite similar weight loss in both groups, restricting sleep reduced the amount of weight lost as body fat by 55% and increased the loss of fat-free body mass by 60%. A loss of fat-free body mass, which includes muscle, can reduce metabolism and make ongoing weight loss and maintenance more difficult. In fact the changes observed with sleep restriction were opposite to what you would want when you are losing weight – namely a greater reduction in body fat and minimal loss of muscle mass. The results also revealed that with longer sleep the subjects lost more than half of their weight as body fat while only 25% of the weight lost during sleep restriction was from fat. The subjects also reported increased hunger levels following sleep restriction.
While only a small study over relatively short period of time, these findings are consistent with previous studies showing that lack of sleep may impact on weight, and suggest that obtaining adequate sleep should be an important part of any weight loss program.
Nedeltcheva et al. Insufficient Sleep Undermines Dietary Efforts to Reduce Adiposity. Annals of Internal Medicine 2010;153(7): 435-441
September 2010: Question over high protein diets
The findings of three new studies call into question the use of high protein diets.
The first study, reporting on recent findings from the European Prospective Investigations into Cancer and Nutrition (EPIC) study, has found that eating more protein, in place of fat or carbohydrate, may increase your risk of type 2 diabetes. Researchers studied more than 38 000 participants in the EPIC study who didn’t have diabetes when the study began. They completed a food frequency questionnaire to assess dietary intake (including total protein, animal protein and vegetable protein) and the diagnosis of diabetes was verified against medical records. The researchers found that participants with the highest protein intakes were 2.2 times more likely to develop diabetes, as were those with the highest animal protein intakes. Intake of vegetable protein, on the other hand, was not linked with diabetes risk. From their findings, the researchers estimated that eating 5% of energy from either total or animal protein in place of 5% of energy from fat or carbohydrate increased diabetes risk by around 30%. Previous studies have linked a higher intake of animal protein, particularly red meat, with diabetes risk. In this study, however, even when the researchers corrected for meat or dairy intake, they still found an association between total and animal protein intake, suggesting that protein itself may have a detrimental effect on diabetes risk.
A second study, published in the August issue of Circulation, has found that a high intake of red meat may increase the risk of coronary heart disease (CHD) in women. Researchers studied more than 84000 women participating in the Nurse’s Health Study who were followed for 26 years. After adjusting for age smoking, and other risk factors, higher intakes of red meat and high-fat dairy foods were associated with a significantly higher risk of CHD while higher intakes of poultry, fish, and nuts were associated with a much lower risk. They estimated that replacing 1 serve of red meat each day with 1 serve of nuts could reduce the risk of CHD by 30%, replacing with one serve of fish could reduce the risk by 24%, and replacing with 1 serve of poultry could reduce the risk by19%.
These findings question the use of high protein diets, which are typically based on a high intake of red meat and animal protein, suggesting that following such a diet could increase your future risk of type 2 diabetes or heart disease. Furthermore, recent findings from the European Prospective Investigation into Cancer and Nutrition–Physical Activity, Nutrition, Alcohol, Cessation of Smoking, Eating Out of Home and Obesity (EPIC-PANACEA) study found that eating more meat was associated with a greater chance of weight gain. They estimate that an increase in red meat intake of 250g/day (an average size steak) could lead to a 2kg higher weight gain over 5 years. The study authors conclude that a decrease in meat consumption might improve weight management.
Sluijs et al. Dietary Intake of Total, Animal, and Vegetable Protein and Risk of Type 2 Diabetes in the European Prospective Investigation into Cancer and Nutrition (EPIC)-NL Study. Diabetes Care 33:43–48, 2010
Bernstein et al. Major Dietary Protein Sources and Risk of Coronary Heart Disease in Women. Circulation. 2010 Aug 16. [Epub ahead of print]
Vergnaud et al. Meat consumption and prospective weight change in participants of the EPIC-PANACEA study. Am J Clin Nutr 2010;92:398–407.
June 2010: Heart disease risk high in women with PCOS and diabetes
Women with PCOS who have the metabolic syndrome and/or type 2 diabetes are at a very high risk of cardiovascular (heart and blood vessel) disease according to a new consensus statement from the Androgen Excess and Polycystic Ovary Syndrome (AE-PCOS) Society.
The society established a panel to review the current evidence of cardiovascular risk in PCOS and provide recommendations. Based on their findings they made the following conclusions and recommendations:
- Women with PCOS who are obese, who smoke, who have abnormal blood fats or blood pressure or who have impaired glucose tolerance (pre-diabetes) are at risk of cardiovascular disease
- Women with PCOS who have the metabolic syndrome and/or type 2 diabetes mellitus are at high risk for cardiovascular disease
- All women with PCOS should have measurements of their body mass index (based on weight and height), waist circumference, blood fats, blood glucose levels and blood pressure
- Women with PCOS who are obese, older or who have a history of gestational diabetes or family history of type 2 diabetes should have an oral glucose tolerance test to check for diabetes
- All women with PCOS should be assessed for mood disorders including depression.
- Lifestyle management is recommended for women with PCOS to reduce the risk of cardiovascular disease and should aim to improve blood fats – this should include an initial aim of 5-10% weight loss, with a longer-term goal of 10-20% weight loss and maintenance. If risk factors persist after lifestyle changes, insulin-sensitising medications (such as the diabetes medication metformin) and blood pressure and cholesterol-lowering medications should be added.
Polycystic Ovary Syndrome (PCOS) is one of the most common endocrine disorders in women, affecting an estimated 5-10% of women of reproductive age. Women with this condition suffer from irregular periods, infertility and symptoms of excess male hormones such as acne and excess hair growth. It is now known that the majority of women with PCOS have insulin resistance as the underlying cause of their PCOS – insulin resistance is an insensitivity of the muscles and cells to insulin and is the same problem that occurs in type 2 diabetes. Many women with PCOS therefore also have type 2 diabetes or are at risk.
Wild et al. Assessment of Cardiovascular Risk and Prevention of Cardiovascular Disease in Women with the Polycystic Ovary Syndrome: A Consensus Statement by the Androgen Excess and Polycystic Ovary Syndrome (AE-PCOS) Society. The Journal of Clinical Endocrinology & Metabolism Vol. 95, No. 5 2038-2049.
April 2010: Breastfeeding protects against type 2 diabetes
A new Australian study has found that women who breastfeed have a significantly lower risk of developing type 2 diabetes.
Researchers from the University of Western Sydney and colleagues studied the effect of both childbearing and breastfeeding on a women’s subsequent risk of developing type 2 diabetes. They studied close to 53 000 women, collecting information on pregnancies, breastfeeding and diabetes diagnosis.
Their findings were published online ahead of print in Diabetes Care on March 23rd showing that 6% of the women had type 2 diabetes and overall the risk was similar in those who had children and those who didn’t. However among those who had children, the women who had breastfed had a much lower risk of developing type 2 diabetes – they estimated that every year of breastfeeding reduced diabetes risk by about 14%. The researchers also found that compared to women who hadn’t been pregnant, those who had children and who didn’t breastfeed had almost a 50% increased risk of developing diabetes, while those who breastfed for at least 3 months with each child were not at significantly greater risk.
Liu et al. Parity, breastfeeding and the subsequent risk of maternal type 2 diabetes. Published online before print March 23, 2010, doi: 10.2337/dc10-0347
March 2010: Prediction of future diabetes in women with gestational diabetes
Having higher blood glucose levels during pregnancy and a family history of diabetes increases the risk of a woman with gestational diabetes developing type 2 diabetes in the future according to a new study.
It is well known that women with gestational diabetes (diabetes in pregnancy) have a higher risk of developing type 2 diabetes later in life. But not all women go on to develop diabetes so researchers from Lund University in Sweden set out to determine if certain factors could help to predict which women might be more likely to end up with diabetes.
They studied 174 women with gestational diabetes, who had an oral glucose tolerance test during pregnancy and 1, 2 and 5 years after having their baby. They then compared measures of blood glucose control and insulin sensitivity in women who developed abnormal glucose levels compared to those whose glucose levels remained normal.
The researchers found that after 5 years, almost one-third of women had developed diabetes and more than half had some form of abnormal glucose tolerance (ie impaired glucose tolerance, impaired fasting glucose or diabetes). Fasting glucose and HbA1c (a measure of average glucose levels over the past 2-3 months) levels during pregnancy were higher in women who developed diabetes compared to those whose glucose levels remained normal. In fact having an HbA1c of 5.7% or more and a fasting glucose level of 5.2mmol/L or higher increased the chances of developing diabetes four-to-six fold. The researchers also report that having a family history of diabetes or having a greater number of previous pregnancies increased the risk of developing diabetes.
Ekelund et al. Prediction of postpartum diabetes in women with gestational diabetes mellitus. Diabetologia 2010; 53 (3): 452-457.
February 2010: Work & finance-related stress leads to metabolic syndrome
Stressful life events, particularly work and finance-related, may increase the risk of the metabolic syndrome according to a new Finnish study. The metabolic syndrome, also known as syndrome X or the insulin resistance syndrome, is a collection of symptoms (including raised blood glucose levels, blood fats, blood pressure and carrying weight around the middle) which occur together and can increase the risk of type 2 diabetes, heart disease and stroke.
Researchers from the University of Helsinki in Finland studied more than 3400 men and women aged 18 to 78 years who were part of a large, population-based study. They were asked to rate the severity of 15 different stressful life events related to finance, work, social relationships, health and housing.
In comparison with those who didn’t report any extremely stressful life events, those who reported work or finance-related stressful events were significantly more likely to have the metabolic syndrome. This risk was increased further, the more stressful events a person experienced in any of the areas assessed.
The researchers also found that the accumulation of stressful life events was associated with individual components of the metabolic syndrome including insulin resistance, obesity and high triglycerides (blood fats). These findings remained after adjusting for sex, age, lifestyle or family history of diabetes.
While we all know that diet and exercise are important for metabolic health, this study highlights the importance of reducing or managing stress in addition to other lifestyle changes.
Pyykkönen et al. Stressful Life Events and the Metabolic Syndrome: The Prevalence, Prediction and Prevention of Diabetes (PPP)-Botnia Study. Diabetes Care 2010; 33:378-384 .
February 2010: Sleep quality and quantity predicts diabetes risk
Both the quality and quantity of sleep you get can influence your risk of type 2 diabetes, according to the new review of the research in this area.
The authors reviewed all studies published in the topic of sleep and diabetes risk between 1955 and 2009. They found that both the quality and quantity of sleep predicted diabetes risk. More specifically, that:
· Sleeping 5-6 hours per night or less increased the risk of type 2 diabetes by 28%
· Sleeping more than 8-9 hours per night increased the risk by almost 50%
· Having difficulty getting to sleep increased the risk by 57%
· Having trouble staying asleep increased the risk by 84%
The authors suggest that the underlying mechanisms may differ between short and long sleepers, but nonetheless these findings highlight the importance of getting the right amount of good quality sleep when it comes to preventing diabetes.
Cappuccio Quantity and Quality of Sleep and Incidence of Type 2 Diabetes: A systematic review and meta-analysis. Diabetes Care February 2010 vol. 33 no. 2 414-420
February 2010: Dietary fibre prevents weight gain around middle
Eating more dietary fibre may help prevent weight gain and an expanding waistline according to a new study.
Researchers from the National Institute for Public Health and the Environment in Bilthoven, the Netherlands set out to look at the relationship between total dietary fibre, cereal fibre, and fruit and vegetable fibre with changes in weight and waist circumference. They studied more than 89 400 participants from 5 different European countries. They were aged 20 to 78 years and free of cancer, heart disease and diabetes when the study began. Dietary information was collected using food-frequency questionnaires which were specific to the eating habits of each country, and the participants were then followed up for an average of 6.5 years.
After adjustment for follow-up duration; other dietary variables; and baseline anthropometric, demographic, and lifestyle factors there was an inverse association between fibre intake and subsequent changes in weight and waist circumference. In other words, those who ate more fibre were less likely to gain weight, particularly around their waist.
The researchers suggest that while individual effects may be small, these changes could be of public health significance, estimating that a 10g increase in dietary fibre intake would prevent approximately 10% of average weight gain. This increase in fibre could be achieved by switching 2 slices of white bread to grain bread, 1 cup of white pasta to wholemeal pasta and snacking on a small handful of almonds in place of other low fibre snacks.
Du et al. Dietary fiber and subsequent changes in body weight and waist circumference in European men and women. Am J Clin Nutr 2010 Feb;91(2):329-36.
January 2010: Eating slowly improves satiety
The idea that eating quickly may lead to weight gain is not an old wives’ tale according to researchers from the Athens University Medical School in Greece, who have found that eating at a more moderate pace results in a greater production of satiety hormones than eating quickly.
The researchers asked 17 healthy volunteers to consume the same test meal (300ml of ice-cream) on 2 occasions – on one occasion they had to eat the meal in 5 minutes and on the other occasion they were asked to take 30 minutes to finish the meal. In the 3 hours following the meal, measurements were taken of hormones which affect hunger and fullness. The participants were also asked to rate their feeling of hunger and fullness using visual analog scales.
The researchers found that eating slowly resulted in a greater production of satiety hormones than eating quickly. The participants also rated their fullness as being higher immediately following the 30-minute meal compared to the 5-minute meal. Similar results were seen in normal weight and overweight participants.
The researchers conclude that ‘the warming we were given as children that wolfing down your food will make you fat may in fact have a physiological explanation’.
Kokkinos et al. Eating slowly increases the postprandial response of the anorexigenic gut hormones, peptide YY and glucagon-like peptide-1. J Clin Endocrinol Metab. 2010; 95 (1):1-5.
December 2009: Breastfeeding for longer reduces metabolic risks for mum
Breastfeeding is not only good for the newborn baby but may also reduce a mothers long term health risks, particularly for women who had gestational diabetes during their pregnancy.
Researchers from the University of Minnesota and colleagues studied almost 1400 women who were part of the Coronary Artery Risk Development in Young Adults (CARDIA) Study, an ongoing observational study in the US. Women who had not previously given birth and did not have the metabolic syndrome when the study began were followed up after 7, 10, 15 and/or 20 years.
Of the 704 women who gave birth (84 of whom had gestational diabetes, GDM), 120 developed the metabolic syndrome at follow-up. Women with GDM were twice as likely to develop the metabolic syndrome compared to women without GDM. Breastfeeding for a longer period of time was associated with a lower incidence of the metabolic syndrome and this risk reduction was found to be stronger in women with GDM.
The researchers conclude that breastfeeding may have persistent favorable effects on women's cardiometabolic health, particularly for women with a history of gestational diabetes.
Gunderson et al. Duration of Lactation and Incidence of the Metabolic Syndrome in Women of Reproductive Age According to Gestational Diabetes Mellitus Status: A 20-Year Prospective Study in CARDIA—The Coronary Artery Risk Development in Young Adults Study. Published online before print December 3, 2009, doi: 10.2337/db09-1197
December 2009: Family history predicts gestational diabetes risk
Women who have a sibling with diabetes are more than 7 times as likely to develop gestational diabetes (diabetes during pregnancy) than those without a family history according to a new study. This risk is higher than for women who have parents with diabetes.
Researchers from the University of Michigan Medical School in the US and colleagues studied more than 4500 women taking part in the National Health and Nutrition Examination Survey III (NHANES III) who had previously given birth. They were asked about their family history of diabetes and were classified as having a history of gestational diabetes, diagnosed diabetes or neither.
After adjusting for age and race, compared to women with no family history of diabetes:
· Women who had a mother with diabetes had 3 times the risk of developing GDM
· Women who had a father with diabetes had more than 3 times the risk of developing GDM
· Women who had s sibling with diabetes had more than 7 times the risk of developing GDM
Interestingly, a different pattern was seen for risk of type 2 diabetes, where a parental history increased the risk to a greater extent than having a sibling with diabetes – in fact having both parents with diabetes increased the risk of developing type 2 diabetes around eight-fold.
The researchers suggest that gestational diabetes may follow a different pattern of inheritance than type 2 diabetes and conclude that further investigation of these patterns could help identify women who are at particularly high risk of developing type 2 diabetes after having gestational diabetes.
Kim C, Liu T, Valdez R, et al. Does frank diabetes in first-degree relatives of a pregnant woman affect the likelihood of her developing gestational diabetes mellitus or nongestational diabetes? Am J Obstet Gynecol 2009;201:576.e1-6
November 2009: Male relatives of women with PCOS at risk for Metabolic Syndrome
There is a high prevalence of metabolic syndrome in fathers and brothers of women with polycystic ovary syndrome (PCOS), according to researchers from the Boston University School of Medicine.
Women with PCOS have been found to have twice the risk of the metabolic syndrome compared to the general population, and the risk is also higher in their mothers and sisters. In this study the researchers studied more than 200 fathers and almost 60 brothers of women with PCOS, comparing them to more than 1600 subjects of similar age and race, taking part in a large national study.
The metabolic syndrome, also known as syndrome X or the insulin resistance syndrome, is a collection of symptoms (including raised blood glucose levels, blood fats, blood pressure and carrying weight around the middle) which occur together and can increase the risk of type 2 diabetes, heart disease and stroke.
The researchers found that first-degree male relatives of women with PCOS do indeed have a higher risk of the metabolic syndrome. In fact 42% of fathers and 22% of brothers of women with PCOS had the metabolic syndrome, compared to 32% and 9% of the general population, respectively. Although not the case in women with PCOS and their female relatives, this study found that body mass index (BMI) accounted for the higher risk in male relatives – once they controlled for BMI, the rates were similar to the general population.
The authors conclude, however, that screening for metabolic syndrome should be considered in male first-degree relatives of women with PCOS.
Coviello et al. High prevalence of metabolic syndrome in first-degree male relatives of women with polycystic ovary syndrome is related to high rates of obesity. J Clin Endocrinol Metab 2009;94:4361-4366.
November 2009: Combined diet and exercise the key to improving insulin resistance
Combining diet and exercise, rather than diet or exercise alone, leads to significantly greater improvements in body fat distribution and insulin resistance, according to the findings of a new study. Insulin resistance is the underlying problem in type 2 diabetes and PCOS.
Researchers from the University of Arkansas for Medical Sciences studied 34 obese older men and women who were randomised to one of four groups: the first two groups aimed to lose weight, one through diet (reducing their energy intake) and the second through exercise plus diet. A third group underwent exercise training without weight loss (they ate more to prevent weight loss due to their increased activity) and a fourth group acted as controls. The study was designed so that the two weight loss groups lost a similar amount of weight.
The researchers found that while weight loss was similar in the diet and exercise + diet groups, the latter group lost significantly more visceral fat (also known as abdominal fat, or fat stored around the middle) compared to those who dieted only or the exercise only group. Improvements in insulin resistance were also significantly greater in the exercise + diet group compared to the diet or exercise only groups.
The researchers conclude that a combination of diet and exercise is the optimal intervention for improving body fat distribution and insulin resistance.
Coker et al. The Impact of Exercise Training Compared to Caloric Restriction on Hepatic and Peripheral Insulin Resistance in Obesity. The Journal of Clinical Endocrinology & Metabolism Vol. 94, No. 11 4258-4266
November 2009: Exercise, not genes, predicts body fat levels
We can’t always blame our genes for being overweight according to Finnish researchers – it’s the amount of exercise we get that influences how much fat we carry.
While exercise is thought to reduce body fat levels most studies have only been short-term and many are limited by genetic selection. So these researchers studied 16 middle-aged same-sex twin pairs (both identical and non-identical) who had different physical activity levels (ie one twin was significantly more active than the other) over a 32 year follow-up period. They found that compared to their active siblings, the physically inactive twins had:
· 50% more visceral fat (also know as abdominal fat or fat stored around the middle)
· 170% more liver fat
· 54% more intramuscular fat (fat located throughout muscle)
All three types of fat are considered ‘high risk’, contributing to diabetes and heart disease risk.
The researchers also found that fitness level (measured by peak oxygen uptake) was inversely associated with intramuscular and visceral fat, suggesting that the twins who were fitter were less likely to be carrying excess body fat.
The researchers conclude that regular physical activity appears to be an important factor in preventing the accumulation of high-risk fat over time, even after controlling for genetics and childhood environment. They recommend that the role of regular leisure-time physical activity should be emphasized in the prevention and treatment of obesity.
Leskinen et al. Leisure-time physical activity and high-risk fat: a longitudinal population-based twin study. International Journal of Obesity 2009; 33: 1211–1218
April 2009: Exercise reduces loss of lean muscle during weight loss
Exercising at a moderate or vigorous level during weight loss can reduce the loss of lean muscle tissue associated with dieting but doesn’t affect abdominal fat loss, according to the findings of a new study.
Researchers from the Wake Forest University School of Medicine in the US studied 112 overweight and obese postmenopausal women who were assigned to one of three 20 week interventions:
- Calorie restriction (dieting) only
- Calorie restriction plus moderate-intensity aerobic exercise
- Calorie restriction plus vigorous-intensity aerobic exercise
The exercise involved walking on a treadmill at an intensity of 45-50% (moderate intensity) or 70-75% (vigorous intensity) of heart rate reserve. The study was designed so that the energy deficit (the difference between what they ate and how much energy they used up with exercise) was the same for each group.
Ninety-five women completed the study and lost, on average, 12.1kg over the 20 week study. The researchers found that all groups achieved a similar reduction in abdominal visceral fat – around 25%. However those in the vigorous-intensity group increased their fitness levels (measured by VO2max) to a greater extent and increased fitness levels were related to loss of abdominal fat. They also found that diet only group lost more lean body mass than either exercise group. Loss of lean muscle reduces metabolic rate and can make continued weight loss and maintenance more difficult.
Previous studies have shown similar findings. For example a similar study (comparing diet only versus diet plus exercise over 20 weeks) was recently published involving 94 overweight and obese women with polycystic ovary syndrome (PCOS). Like the study above, both the diet only and exercising groups lost similar amounts of weight (in this study it was 8.7-10.6%) but the researchers found that almost 50% of the weight loss in the diet only group (3.8kg) was due to a reduction in fat free mass. The exercising groups (either aerobic or combined aerobic-resistance training) lost approximately 45% more fat mass and 60% less fat free mass than the diet only group.
Nicklas et al. Effect of exercise intensity on abdominal fat loss during calorie restriction in overweight and obese postmenopausal women: a randomized, controlled trial. Am J Clin Nutr 89: 1043-1052, 2009.
Thomson et al. The effect of a hypocaloric diet with and without exercise training on body composition, cardiometabolic risk profile, and reproductive function in overweight and obese women with polycystic ovary syndrome. J Clin Endocrinol Metab 2008.
August 2011: Magnesium supplement improves insulin sensitivity
A new study has found that taking a magnesium supplement improves insulin sensitivity, the underlying problem in PCOS and type 2 diabetes.
A number of studies have found that magnesium plays a role in glucose and insulin metabolism and previous research has found a link between magnesium intake and risk of type 2 diabetes. In this study, researchers from the Justus-Liebig-University in Germany wanted to see if taking a magnesium supplement would improve insulin sensitivity in overweight individuals who were insulin resistant but didn’t have diabetes. Insulin resistance means that insulin is unable to work effectively in the body to reduce blood glucose levels and is the underlying problem in type 2 diabetes. Individuals who are insulin resistant are therefore at risk of developing diabetes.
They studied 32 overweight subjects aged between 30 and 70 years who had normal magnesium levels. They were randomised to two groups – one which took a magnesium supplement (365mg of magnesium aspartate hydrochloride) and the other a placebo. The study lasted for 6 months.
The results are published in the March issue of Diabetes, Obesity and Metabolism, showing that the group taking magnesium had greater improvements in fasting blood glucose levels and a number of measures of insulin sensitivity compared to the placebo group. Blood pressure and cholesterol levels didn’t change significantly.
The researchers point out that the improvements in insulin sensitivity seen in their study were similar to that of a previous study with the diabetes medication metformin. They also highlight the fact that these results were seen despite the fact that the study subjects had normal magnesium levels to start with – many of the previous studies looking at the benefits of magnesium have been in individuals with low magnesium levels.
They study supports the importance of a good dietary intake of magnesium, particularly for those at risk of type 2 diabetes, and suggests that supplementing with magnesium may be beneficial even in those who are not deficient in this mineral. Good food sources include wholegrains, nuts, seeds (particularly pumpkin seeds), legumes, green leafy vegetables and dark chocolate.
Mooren et al. Oral magnesium supplementation reduces insulin resistance in non-diabetic subjects - a double-blind, placebo-controlled, randomized trial. Diabetes Obes Metab. 2011 Mar;13(3):281-4.
July 2011: Cereal fibre, not protein, improves insulin sensitivity
A new German study suggests that a high protein diet is not the answer to reducing insulin resistance, the underlying problem in PCOS and type 2 diabetes.
Researchers from the Heinrich-Heine University Düsseldorf in Germany compared the effects of a high protein diet, a high cereal fibre diet and a third diet with moderate increases in both protein and cereal fibres. All diets contained the same amount of energy, or kilojoules. They studied 111 overweight adults with features of the metabolic syndrome (which include raised blood glucose levels, triglycerides and blood pressure, low ‘good’ HDL cholesterol and carrying weight around the middle) and 84 of these subjects completed the study, They were randomly allocated to one of four groups (the three diet groups mentioned above and a control group which were given basic healthy eating advice). All participants were provided with a dietary supplement to take twice/day, to help them to achieve their particular dietary targets.
During the first 6 weeks the high protein (HP) group consumed 28% of their energy from protein compared to only 17% in the control and high cereal fibre (HCF) groups and 23% in the mixed group. The fibre content of the diets during this initial phase was 43g per day in the HCF group, 13g in the HP group,14g in the control group and 26g in the mixed group. For the following 12 weeks the protein intake in the HP group and the fibre content of the HCF group were slightly lower (26% instead of 28% and 41g instead of 43g).
Published ahead of print on June 1st in the American Journal of Clinical Nutrition, the results show that the diets had significantly different effects in insulin sensitivity. After 6 weeks on the HCF diet insulin sensitivity was 25% higher compared to the HP diet. Insulin sensitivity is a measure of how well insulin works in the body – insulin resistance, or poor insulin sensitivity, is the underlying problem in type 2 diabetes. The difference between the groups had lessened by 18 weeks which the researchers say was most likely explained by the fact that many participants in the HP diet were not sticking as closely to their diet and had reduced their protein intake over time. However the improvement in insulin sensitivity in the HCF group was sustained over the 18 weeks, suggesting that a high cereal fibre diet may have prolonged beneficial effects on insulin sensitivity.
The researchers found that the higher protein intake tended to increase the levels of an enzyme called serine-kinase-6-1 (S6K1) which is known to induce insulin resistance. Interestingly the mixed diet didn’t show the same detrimental effects on insulin sensitivity despite a higher protein intake, which the researchers say may be explained by the fact that the higher intake of cereal fibre in this group interfered with the absorption of protein. They suggest that this may be one explanation for the relationship between higher fibre diets and reduced diabetes risk which has been demonstrated in many previous studies.
Weickert et al. Effects of supplemented isoenergetic diets differing in cereal fiber and protein content on insulin sensitivity in overweight humans. Am J Clin Nutr. 2011 Jun 1. [Epub ahead of print]
June 2011: Excess egg consumption increases GDM risk
Eating one or more eggs each day before or during pregnancy may increase the chances of developing gestational diabetes (GDM) according to a new study published in the March issue of the American Journal of Epidemiology.
Researchers from the Center for Perinatal Studies at the Swedish Medical Center in Seattle, in the US looked at the findings of two studies which investigated the relationship between egg consumption prior to or during early pregnancy and GDM risk.
The first study of more than 3100 women found that women who ate 10 or more eggs per week had more than 2.5 times the risk of developing GDM compared to those who didn’t eat eggs. Those who at 7 or more eggs per week increased their risk 1.8 fold compared to those who ate less than 7 eggs per week.
The second study, a case-control study, compared 185 women who developed GDM with 411 women who didn’t develop diabetes (controls). Similar to the first study, they found that the odds of developing GDM was 2.7 times higher in those who ate 7 or more eggs per week compared to those who ate less than 7 per week. In both cases, the findings were independent of other factors which may affect diabetes risk.
Both studies also found that the risk of GDM was higher in those who consumed more cholesterol in their diet. In the first study the risk was 2.4 fold higher in those with the highest cholesterol intakes (294mg per day or more) compared to those with the lowest intakes (less than 151mg/day); in the second study the risk was 2.9 times higher. A medium egg contains around 200mg of cholesterol.
These studies support the findings of previous research showing a link between high egg intake and type 2 diabetes, and between cholesterol intakes and both gestational diabetes and type 2 diabetes. The researchers suggest that further studies are needed to explore the mechanisms behind this increased risk.
In the meantime, while eggs are a convenient and nutritious food, the study suggests that, like most things, they should be consumed in moderation and alternated with other protein foods, particularly if you are trying to conceive.
Qiu et al. Risk of gestational diabetes mellitus in relation to maternal egg and cholesterol intake.Am J Epidemiol. 2011 Mar 15;173(6):649-58. Epub 2011 Feb 15.
May 2011: Vegetarian diet improves insulin sensitivity
A vegetarian diet improves insulin sensitivity and abdominal fat more than a conventional diabetic diet according to a new study published in the May issue of Diabetic Medicine.
Researchers from the 1st Faculty of Medicine Institute of Endocrinology in Prague in the Czech Republic studied 74 subjects with type 2 diabetes who were randomised to either a vegetarian diet or control group who followed a conventional diabetic diet. Both groups consumed the same amount of energy (calories or kilojoules) which was restricted in order to achieve weight loss. The study lasted 24 weeks and all meals were provided to subjects. During the second 12 weeks of the study the participants were also prescribed an individualised exercise program, prior to this they were asked not to alter their exercise habits.
The vegetarian diet consisted of vegetables, grains, legumes, fruits and nuts, with 60% of energy from carbohydrates, 15% from protein and 25% from fat. The only animal product allowed was one serving of low-fat yogurt each day. The conventional diabetic diet was provided according to the dietary guidelines of the Diabetes and Nutrition Study Group (DNSG) of the European Association for the Study of Diabetes (EASD). It contained 50% of total energy from carbohydrates, 20% protein, less than 30% Fat (with less than 7% saturated fat and less than 200 mg of cholesterol per day). Alcohol was limited in both groups to one standard drink per day for women and two per day for men.
The researchers found that after 24 weeks, 43% of those in the vegetarian diet group had reduced their diabetes medication compared to only 5% of those in the control group. The vegetarian dieters lost most weight - 6.2kg versus 2.3kg, and also had greater reductions in body fat, particularly visceral fat, or fat stored around the middle. Insulin sensitivity improved by 30% in the vegetarian diet group compared to 20% in the control group, suggesting that the vegetarian diet was better at improving how insulin works in the body – insulin resistance or poor insulin sensitivity, is the underlying problem in type 2 diabetes and PCOS.
Markers of oxidative stress were also improved to a greater extent on the vegetarian diet and the researchers suggest that this may be the main contributor to the improvement in insulin resistance. Oxidation causes damage to the cells in our body and is believed to be an important factor in the development of a number of chronic as well as playing a role in ageing. Interestingly, the addition of exercise increased the differences between the groups – in other words the improved outcomes in the vegetarian diet were even greater when they were also exercising.
Kahleova et al. Vegetarian diet improves insulin resistance and oxidative stress markers more than conventional diet in subjects with Type 2 diabetes. Diabet Med. 2011 May;28(5):549-59. doi: 10.1111/j.1464-5491.2010.03209.x.
April 2011: Vitamin D levels important in gestational diabetes
A new Australian study has found that low vitamin D levels are linked with poorer blood glucose control in women with gestational diabetes (diabetes in pregnancy).
Researchers from Westmead Hospital in Sydney studied almost 150 women attending the gestational diabetes (GDM) clinic at Westmead Hospital from February 2007 to February 2008, who were on average around 35 weeks of pregnancy. They had blood tests during the third trimester of pregnancy to measure HbA1c (which reflects average blood glucose control over the previous 2-3 months) and vitamin D levels. GDM was diagnosed using an oral glucose tolerance test (OGTT).
The results are published in the April 4 issue of the Medical Journal of Australia showing that 41% of the women had low levels of vitamin D (50nmol/L or below). Lower levels were seen in women from Middle Eastern and Indian backgrounds, as well as women who performed home duties compared to those in paid employment. Not surprisingly, vitamin D levels were much higher in summer than during other seasons. Weight did not appear to affect vitamin D levels.
Women with lower vitamin D levels were found to have higher blood glucose levels – both fasting and 2 hour glucose levels during the oral glucose tolerance test, and HbA1c levels. Low vitamin D levels were associated with a higher HbA1c, independent of other factors.
The authors suggest randomised trials are needed to determine whether vitamin D plays a role in blood glucose control in gestational diabetes. In the meantime, considering the high prevalence of vitamin D deficiency they found in the study, and the fact that low vitamin D levels in pregnancy can have other adverse effects for the unborn baby, they recommend routine testing of vitamin D for all pregnant women, either alongside or prior to screening for GDM.
Lau et al. Serum 25-hydroxyvitamin D and glycated haemoglobin levels in women with gestational diabetes mellitus. Med J Aust. 2011 Apr 4;194(7):334-7.
March 2011: More evidence for link between pregnancy glucose and childhood obesity
A new study has found that children of women who did not have diabetes or develop gestational diabetes but who had slightly elevated glucose levels in pregnancy, were more likely to be overweight by age 3.
It is now well established that children of women with pre-existing diabetes or gestational diabetes (diabetes which develops in pregnancy) are more likely to develop obesity and type 2 diabetes later in life, as a result of exposure to excess glucose in utero. In the current study researchers looked a the relationship between a child’s BMI (body mass index) at age 3 years and their mothers blood glucose level (measured during a glucose challenge test at around 27 weeks gestation to screen for gestational diabetes) in women without pre-existing or gestational diabetes. They studied 263 mother- child pairs.
They found that at 3 years of age, 21% of children were overweight and 5% obese. After controlling for mum’s pre-pregnancy weight, children whose mothers had a glucose level of 7.2mmol/L or more were more than twice as likely to be overweight or obese compared to those with a glucose level under 5.6mmol/L. The current cut-off for the diagnosis of gestational diabetes is 7.8mmol/L.
The researchers suggest that even in the absence of diagnosed diabetes or gestational diabetes, children who are exposed to higher glucose levels in pregnancy are more likely to develop weight problems later in life. They suggest that this is a modifiable factor that could reduce future obesity risks for a child and suggest that women with raised glucose levels, even if they don’t meet the current criteria for gestational diabetes, may need intervention to reduce their child’s exposure to excess glucose during pregnancy.
Deierlein et al. The Association Between Maternal Glucose Concentration and Child BMI at Age 3 Years. Diabetes Care 2011; 34: 480-484.
February 2011: Weight gain in pregnancy.....not too little and not too much
Researchers from the EDEN study group looked at the relationship between pre-pregnancy weight and weight gain during pregnancy with pregnancy and birth outcomes, both in women with and without gestational diabetes (diabetes in pregnancy) and high blood pressure. They found that being overweight before falling pregnant (ie having a high BMI or body mass index) increased the risk of having a large baby by more than 3-fold, while gaining a larger amount of weight during pregnancy increased the risk 1.6 times. However when they excluded women with gestational diabetes and high blood pressure, the risks were closer - 2.6 times higher for the overweight women and 2.1 times higher for those who gained more weight during their pregnancy.
On the other hand, women who had a low weight gain during pregnancy had more than double the risk of having a pre-term baby and this was increased to 2.7 fold after accounting for high blood pressure and gestational diabetes.
The researchers comment that these results reinforce the association between low maternal weight gain during pregnancy and premature birth, and high weight gain with risk of having a large baby. They also highlight their findings showing a link between weight gain in pregnancy and the risk of large babies in women without gestational diabetes or high blood pressure, suggesting that avoiding excess weight gain is important even for women without these risk factors. However they comment that this must be monitored closely to avoid low weight gain and the associated risk of pre-term delivery. For women who are overweight, losing weight prior to falling pregnant can reduce these risks.
Heude et al. Pre-Pregnancy Body Mass Index and Weight Gain During Pregnancy: Relations with Gestational Diabetes and Hypertension, and Birth Outcomes. Matern Child Health J. 2011 Jan 22. [Epub ahead of print]
January 2011: High protein no better than high carb diets for type 2 diabetes
A high protein diet is no better than a higher carbohydrate diet for improving glucose control, weight loss and heart disease risk factors in people with type 2 diabetes according to a new Australian study.
Dietary changes and weight loss are the cornerstone of management of type 2 diabetes but there is still debate over the optimal composition of the diet, particularly when it comes to protein and carbohydrate intakes. So researchers from the RMIT University in Melbourne set out to compare the effects of two low fat diets, one higher in protein and one higher in carbohydrate, in individuals with type 2 diabetes.
They studied almost 100 subject with type 2 diabetes who were randomly allocated to one of the groups – both diets were low in fat (30% of total energy) but differed in the proportions of protein and carbohydrate – the high protein diet aimed for 30% of energy from protein and 40% from carbohydrate while the higher carb diet aimed for 55% of energy from carbohydrate and 15% from protein. Both diets recommended low GI carbs. Each participant was provided with dietary advice by a dietitian including menu plans and food lists.
Both groups had similar improvements in HbA1c levels (a measure of average glucose control over the past 2-3 months), weight loss and blood fats (cholesterol and triglyceride levels). There was also no difference between the groups in blood pressure, kidney function or calcium losses. It is though that the latter could potentially worsen on a higher protein diet but this was not seen in the current study.
They also measured dietary self-management (participants were asked to rate their own ability to follow their prescribed diet) and found that that this was a significant predictor of success. In fact those with the highest self-management score at 1 year lost an average of 5.5 kg of body weight and reduced their HbA1c levels by 0.87% whereas participants with the lowest self-management score had little change in weight or HbA1c (reduced by 0.03kg and 0.03%, respectively).
The researchers conclude that energy restriction and weight loss are the best predictors of improved blood glucose control in type 2 diabetes, not dietary composition, and suggest that future studies should focus on developing skills to improve dietary adherence and self-management rather than modifying dietary composition.
Larsen et al. The effect of high-protein, low-carbohydrate diets in the treatment of type 2 diabetes: a 12 month randomised controlled trial. Diabetologia. 2011 Jan 20. [Epub ahead of print]
December 2010: Pre-pregnancy exercise reduces gestational diabetes risk
Women who are more active before falling pregnant or early in their pregnancy are less likely to develop gestational diabetes according to comprehensive review of current research.
Gestational diabetes (GDM) is diabetes which first presents during pregnancy and resolves after the pregnancy, although women with GDM are at increased risk of developing type 2 diabetes in later life. It is recommended that all women are screened for GDM at 24-28 weeks gestation, or earlier if they are at high risk (which includes women with PCOS). Blood glucose levels must be kept well controlled during pregnancy (with diet, exercise, and insulin if required) to reduce the risk of complications to both mother and baby.
Researchers from the Harvard School of Public Health conducted a systematic review of studies looking at the relationship between physical activity and the development of GDM. They found 12 studies, 7 which assessed pre-pregnancy activity (in a total of almost 35 000 women) and 5 which looked at activity levels in early pregnancy (in a total of just over 4400 women).Their finding are published in the December issue of Diabetes Care showing that compared to women with the lowest physical activity levels before pregnancy, those who were most active had a 55% lower risk of developing GDM. When it came to exercise in early pregnancy, the most active women were 24% less likely to develop GDM compared to those who did little activity.
The researchers conclude that promoting physical activity among women of reproductive age may be one way to reduce the risk of GDM and the complications for children born to these women. They also recommend that further research is needed to determine whether beginning an exercise routine in early pregnancy can reduce the risk in women who were previously inactive, and to see if there is an additive effect of being active both before and during early pregnancy.
Tobias et al. Physical activity before and during pregnancy and risk of gestational diabetes mellitus: a meta-analysis. Diabetes Care. 2010 Sep 27. [Epub ahead of print]
December 2010: Low GI diet plus exercise the key to type 2 diabetes prevention
A lifestyle program involving exercise, diet and weight loss may delay the onset of type 2 diabetes when the diet has a high glycemic index (GI), but has the potential to actually prevent diabetes if a low GI diet is followed. That’s the findings of a new study published in the November issue of the American Journal of Clinical Nutrition.
The researchers studied 22 older, obese individuals with pre-diabetes. They took part in a 12 week exercise training program and at the same time were randomly assigned to follow either a low GI or high GI diet. Each exercise session was supervised and the program consisted of walking on a treadmill or riding an exercise bike for 1 hour per day on 5 days per week, working at 85% of their maximum heart rate. All food and beverages were provided to participants on a daily basis. The composition of the diets was similar, apart from the GI which was 40 in the low GI group and 80 in the high GI group.
The researchers report that both groups lost similar amounts of weight and had similar improvements in insulin sensitivity. However only the low GI diet group had reductions in insulin secretion after being given a glucose load, while insulin secretion actually increased on the high GI diet.
The development of type 2 diabetes starts insulin resistance, when the body’s insulin is unable to work properly. Initially, the body makes extra insulin to overcome this resistance (this is called hyperinsulinemia, or high levels of insulin in the blood), so blood glucose levels remain normal. But if nothing is done to reduce the extra workload of the body’s insulin producing cells (beta cells), eventually they can’t keep up and blood glucose levels start to rise. At this stage the beta cells just can’t keep up making enough insulin to overcome the resistance of the muscles and cells to its action. As blood glucose levels rise, the individual progresses from having insulin resistance to impaired glucose tolerance/impaired fasting glucose (known as pre-diabetes) to diabetes itself.
This means that preventing diabetes requires both an improvement in insulin resistance (making the muscles and cells more sensitive to insulin) and reducing the stress on the beta cells to produce insulin. This study found that while both diets, in combination with exercise and weight loss, improved insulin sensitivity, that only the low GI diet helped in reducing the workload on the insulin-producing beta cells. The researchers suggest that this may be the optimal lifestyle treatment for prevention of type 2 diabetes.
Solomon et al. A low–glycemic index diet combined with exercise reduces insulin resistance, postprandial hyperinsulinemia, and glucose-dependent insulinotropic polypeptide responses in obese, prediabetic humans. Am J Clin Nutr 2010;92:1359–68.
November 2010: Lack of sleep reduces fat loss
If you want to lose body fat you should not only concentrate on your diet but also make sure you are getting enough sleep according to the findings of a new US study.
Researchers studied ten overweight but otherwise healthy, non-smoking adults aged 35 to 49 years. They took part in two 2 week experiments during which time they lived in the research centre where their food intake, exercise and sleep was monitored. In both experimental periods, they were provided with a diet moderately restricted in energy to produce weight loss. They were only able to eat and drink what was provided. In one experimental period they were allowed to sleep for 8.5 hours per night and in the other period sleep was restricted to only 5.5 hours per night. They were randomly assigned to the short or long sleep period first and then took part in the other experiment after a minimum of at least 3 months. .
Despite similar weight loss in both groups, restricting sleep reduced the amount of weight lost as body fat by 55% and increased the loss of fat-free body mass by 60%. A loss of fat-free body mass, which includes muscle, can reduce metabolism and make ongoing weight loss and maintenance more difficult. In fact the changes observed with sleep restriction were opposite to what you would want when you are losing weight – namely a greater reduction in body fat and minimal loss of muscle mass. The results also revealed that with longer sleep the subjects lost more than half of their weight as body fat while only 25% of the weight lost during sleep restriction was from fat. The subjects also reported increased hunger levels following sleep restriction.
While only a small study over relatively short period of time, these findings are consistent with previous studies showing that lack of sleep may impact on weight, and suggest that obtaining adequate sleep should be an important part of any weight loss program.
Nedeltcheva et al. Insufficient Sleep Undermines Dietary Efforts to Reduce Adiposity. Annals of Internal Medicine 2010;153(7): 435-441
September 2010: Question over high protein diets
The findings of three new studies call into question the use of high protein diets.
The first study, reporting on recent findings from the European Prospective Investigations into Cancer and Nutrition (EPIC) study, has found that eating more protein, in place of fat or carbohydrate, may increase your risk of type 2 diabetes. Researchers studied more than 38 000 participants in the EPIC study who didn’t have diabetes when the study began. They completed a food frequency questionnaire to assess dietary intake (including total protein, animal protein and vegetable protein) and the diagnosis of diabetes was verified against medical records. The researchers found that participants with the highest protein intakes were 2.2 times more likely to develop diabetes, as were those with the highest animal protein intakes. Intake of vegetable protein, on the other hand, was not linked with diabetes risk. From their findings, the researchers estimated that eating 5% of energy from either total or animal protein in place of 5% of energy from fat or carbohydrate increased diabetes risk by around 30%. Previous studies have linked a higher intake of animal protein, particularly red meat, with diabetes risk. In this study, however, even when the researchers corrected for meat or dairy intake, they still found an association between total and animal protein intake, suggesting that protein itself may have a detrimental effect on diabetes risk.
A second study, published in the August issue of Circulation, has found that a high intake of red meat may increase the risk of coronary heart disease (CHD) in women. Researchers studied more than 84000 women participating in the Nurse’s Health Study who were followed for 26 years. After adjusting for age smoking, and other risk factors, higher intakes of red meat and high-fat dairy foods were associated with a significantly higher risk of CHD while higher intakes of poultry, fish, and nuts were associated with a much lower risk. They estimated that replacing 1 serve of red meat each day with 1 serve of nuts could reduce the risk of CHD by 30%, replacing with one serve of fish could reduce the risk by 24%, and replacing with 1 serve of poultry could reduce the risk by19%.
These findings question the use of high protein diets, which are typically based on a high intake of red meat and animal protein, suggesting that following such a diet could increase your future risk of type 2 diabetes or heart disease. Furthermore, recent findings from the European Prospective Investigation into Cancer and Nutrition–Physical Activity, Nutrition, Alcohol, Cessation of Smoking, Eating Out of Home and Obesity (EPIC-PANACEA) study found that eating more meat was associated with a greater chance of weight gain. They estimate that an increase in red meat intake of 250g/day (an average size steak) could lead to a 2kg higher weight gain over 5 years. The study authors conclude that a decrease in meat consumption might improve weight management.
Sluijs et al. Dietary Intake of Total, Animal, and Vegetable Protein and Risk of Type 2 Diabetes in the European Prospective Investigation into Cancer and Nutrition (EPIC)-NL Study. Diabetes Care 33:43–48, 2010
Bernstein et al. Major Dietary Protein Sources and Risk of Coronary Heart Disease in Women. Circulation. 2010 Aug 16. [Epub ahead of print]
Vergnaud et al. Meat consumption and prospective weight change in participants of the EPIC-PANACEA study. Am J Clin Nutr 2010;92:398–407.
June 2010: Heart disease risk high in women with PCOS and diabetes
Women with PCOS who have the metabolic syndrome and/or type 2 diabetes are at a very high risk of cardiovascular (heart and blood vessel) disease according to a new consensus statement from the Androgen Excess and Polycystic Ovary Syndrome (AE-PCOS) Society.
The society established a panel to review the current evidence of cardiovascular risk in PCOS and provide recommendations. Based on their findings they made the following conclusions and recommendations:
- Women with PCOS who are obese, who smoke, who have abnormal blood fats or blood pressure or who have impaired glucose tolerance (pre-diabetes) are at risk of cardiovascular disease
- Women with PCOS who have the metabolic syndrome and/or type 2 diabetes mellitus are at high risk for cardiovascular disease
- All women with PCOS should have measurements of their body mass index (based on weight and height), waist circumference, blood fats, blood glucose levels and blood pressure
- Women with PCOS who are obese, older or who have a history of gestational diabetes or family history of type 2 diabetes should have an oral glucose tolerance test to check for diabetes
- All women with PCOS should be assessed for mood disorders including depression.
- Lifestyle management is recommended for women with PCOS to reduce the risk of cardiovascular disease and should aim to improve blood fats – this should include an initial aim of 5-10% weight loss, with a longer-term goal of 10-20% weight loss and maintenance. If risk factors persist after lifestyle changes, insulin-sensitising medications (such as the diabetes medication metformin) and blood pressure and cholesterol-lowering medications should be added.
Polycystic Ovary Syndrome (PCOS) is one of the most common endocrine disorders in women, affecting an estimated 5-10% of women of reproductive age. Women with this condition suffer from irregular periods, infertility and symptoms of excess male hormones such as acne and excess hair growth. It is now known that the majority of women with PCOS have insulin resistance as the underlying cause of their PCOS – insulin resistance is an insensitivity of the muscles and cells to insulin and is the same problem that occurs in type 2 diabetes. Many women with PCOS therefore also have type 2 diabetes or are at risk.
Wild et al. Assessment of Cardiovascular Risk and Prevention of Cardiovascular Disease in Women with the Polycystic Ovary Syndrome: A Consensus Statement by the Androgen Excess and Polycystic Ovary Syndrome (AE-PCOS) Society. The Journal of Clinical Endocrinology & Metabolism Vol. 95, No. 5 2038-2049.
April 2010: Breastfeeding protects against type 2 diabetes
A new Australian study has found that women who breastfeed have a significantly lower risk of developing type 2 diabetes.
Researchers from the University of Western Sydney and colleagues studied the effect of both childbearing and breastfeeding on a women’s subsequent risk of developing type 2 diabetes. They studied close to 53 000 women, collecting information on pregnancies, breastfeeding and diabetes diagnosis.
Their findings were published online ahead of print in Diabetes Care on March 23rd showing that 6% of the women had type 2 diabetes and overall the risk was similar in those who had children and those who didn’t. However among those who had children, the women who had breastfed had a much lower risk of developing type 2 diabetes – they estimated that every year of breastfeeding reduced diabetes risk by about 14%. The researchers also found that compared to women who hadn’t been pregnant, those who had children and who didn’t breastfeed had almost a 50% increased risk of developing diabetes, while those who breastfed for at least 3 months with each child were not at significantly greater risk.
Liu et al. Parity, breastfeeding and the subsequent risk of maternal type 2 diabetes. Published online before print March 23, 2010, doi: 10.2337/dc10-0347
March 2010: Prediction of future diabetes in women with gestational diabetes
Having higher blood glucose levels during pregnancy and a family history of diabetes increases the risk of a woman with gestational diabetes developing type 2 diabetes in the future according to a new study.
It is well known that women with gestational diabetes (diabetes in pregnancy) have a higher risk of developing type 2 diabetes later in life. But not all women go on to develop diabetes so researchers from Lund University in Sweden set out to determine if certain factors could help to predict which women might be more likely to end up with diabetes.
They studied 174 women with gestational diabetes, who had an oral glucose tolerance test during pregnancy and 1, 2 and 5 years after having their baby. They then compared measures of blood glucose control and insulin sensitivity in women who developed abnormal glucose levels compared to those whose glucose levels remained normal.
The researchers found that after 5 years, almost one-third of women had developed diabetes and more than half had some form of abnormal glucose tolerance (ie impaired glucose tolerance, impaired fasting glucose or diabetes). Fasting glucose and HbA1c (a measure of average glucose levels over the past 2-3 months) levels during pregnancy were higher in women who developed diabetes compared to those whose glucose levels remained normal. In fact having an HbA1c of 5.7% or more and a fasting glucose level of 5.2mmol/L or higher increased the chances of developing diabetes four-to-six fold. The researchers also report that having a family history of diabetes or having a greater number of previous pregnancies increased the risk of developing diabetes.
Ekelund et al. Prediction of postpartum diabetes in women with gestational diabetes mellitus. Diabetologia 2010; 53 (3): 452-457.
February 2010: Work & finance-related stress leads to metabolic syndrome
Stressful life events, particularly work and finance-related, may increase the risk of the metabolic syndrome according to a new Finnish study. The metabolic syndrome, also known as syndrome X or the insulin resistance syndrome, is a collection of symptoms (including raised blood glucose levels, blood fats, blood pressure and carrying weight around the middle) which occur together and can increase the risk of type 2 diabetes, heart disease and stroke.
Researchers from the University of Helsinki in Finland studied more than 3400 men and women aged 18 to 78 years who were part of a large, population-based study. They were asked to rate the severity of 15 different stressful life events related to finance, work, social relationships, health and housing.
In comparison with those who didn’t report any extremely stressful life events, those who reported work or finance-related stressful events were significantly more likely to have the metabolic syndrome. This risk was increased further, the more stressful events a person experienced in any of the areas assessed.
The researchers also found that the accumulation of stressful life events was associated with individual components of the metabolic syndrome including insulin resistance, obesity and high triglycerides (blood fats). These findings remained after adjusting for sex, age, lifestyle or family history of diabetes.
While we all know that diet and exercise are important for metabolic health, this study highlights the importance of reducing or managing stress in addition to other lifestyle changes.
Pyykkönen et al. Stressful Life Events and the Metabolic Syndrome: The Prevalence, Prediction and Prevention of Diabetes (PPP)-Botnia Study. Diabetes Care 2010; 33:378-384 .
February 2010: Sleep quality and quantity predicts diabetes risk
Both the quality and quantity of sleep you get can influence your risk of type 2 diabetes, according to the new review of the research in this area.
The authors reviewed all studies published in the topic of sleep and diabetes risk between 1955 and 2009. They found that both the quality and quantity of sleep predicted diabetes risk. More specifically, that:
· Sleeping 5-6 hours per night or less increased the risk of type 2 diabetes by 28%
· Sleeping more than 8-9 hours per night increased the risk by almost 50%
· Having difficulty getting to sleep increased the risk by 57%
· Having trouble staying asleep increased the risk by 84%
The authors suggest that the underlying mechanisms may differ between short and long sleepers, but nonetheless these findings highlight the importance of getting the right amount of good quality sleep when it comes to preventing diabetes.
Cappuccio Quantity and Quality of Sleep and Incidence of Type 2 Diabetes: A systematic review and meta-analysis. Diabetes Care February 2010 vol. 33 no. 2 414-420
February 2010: Dietary fibre prevents weight gain around middle
Eating more dietary fibre may help prevent weight gain and an expanding waistline according to a new study.
Researchers from the National Institute for Public Health and the Environment in Bilthoven, the Netherlands set out to look at the relationship between total dietary fibre, cereal fibre, and fruit and vegetable fibre with changes in weight and waist circumference. They studied more than 89 400 participants from 5 different European countries. They were aged 20 to 78 years and free of cancer, heart disease and diabetes when the study began. Dietary information was collected using food-frequency questionnaires which were specific to the eating habits of each country, and the participants were then followed up for an average of 6.5 years.
After adjustment for follow-up duration; other dietary variables; and baseline anthropometric, demographic, and lifestyle factors there was an inverse association between fibre intake and subsequent changes in weight and waist circumference. In other words, those who ate more fibre were less likely to gain weight, particularly around their waist.
The researchers suggest that while individual effects may be small, these changes could be of public health significance, estimating that a 10g increase in dietary fibre intake would prevent approximately 10% of average weight gain. This increase in fibre could be achieved by switching 2 slices of white bread to grain bread, 1 cup of white pasta to wholemeal pasta and snacking on a small handful of almonds in place of other low fibre snacks.
Du et al. Dietary fiber and subsequent changes in body weight and waist circumference in European men and women. Am J Clin Nutr 2010 Feb;91(2):329-36.
January 2010: Eating slowly improves satiety
The idea that eating quickly may lead to weight gain is not an old wives’ tale according to researchers from the Athens University Medical School in Greece, who have found that eating at a more moderate pace results in a greater production of satiety hormones than eating quickly.
The researchers asked 17 healthy volunteers to consume the same test meal (300ml of ice-cream) on 2 occasions – on one occasion they had to eat the meal in 5 minutes and on the other occasion they were asked to take 30 minutes to finish the meal. In the 3 hours following the meal, measurements were taken of hormones which affect hunger and fullness. The participants were also asked to rate their feeling of hunger and fullness using visual analog scales.
The researchers found that eating slowly resulted in a greater production of satiety hormones than eating quickly. The participants also rated their fullness as being higher immediately following the 30-minute meal compared to the 5-minute meal. Similar results were seen in normal weight and overweight participants.
The researchers conclude that ‘the warming we were given as children that wolfing down your food will make you fat may in fact have a physiological explanation’.
Kokkinos et al. Eating slowly increases the postprandial response of the anorexigenic gut hormones, peptide YY and glucagon-like peptide-1. J Clin Endocrinol Metab. 2010; 95 (1):1-5.
December 2009: Breastfeeding for longer reduces metabolic risks for mum
Breastfeeding is not only good for the newborn baby but may also reduce a mothers long term health risks, particularly for women who had gestational diabetes during their pregnancy.
Researchers from the University of Minnesota and colleagues studied almost 1400 women who were part of the Coronary Artery Risk Development in Young Adults (CARDIA) Study, an ongoing observational study in the US. Women who had not previously given birth and did not have the metabolic syndrome when the study began were followed up after 7, 10, 15 and/or 20 years.
Of the 704 women who gave birth (84 of whom had gestational diabetes, GDM), 120 developed the metabolic syndrome at follow-up. Women with GDM were twice as likely to develop the metabolic syndrome compared to women without GDM. Breastfeeding for a longer period of time was associated with a lower incidence of the metabolic syndrome and this risk reduction was found to be stronger in women with GDM.
The researchers conclude that breastfeeding may have persistent favorable effects on women's cardiometabolic health, particularly for women with a history of gestational diabetes.
Gunderson et al. Duration of Lactation and Incidence of the Metabolic Syndrome in Women of Reproductive Age According to Gestational Diabetes Mellitus Status: A 20-Year Prospective Study in CARDIA—The Coronary Artery Risk Development in Young Adults Study. Published online before print December 3, 2009, doi: 10.2337/db09-1197
December 2009: Family history predicts gestational diabetes risk
Women who have a sibling with diabetes are more than 7 times as likely to develop gestational diabetes (diabetes during pregnancy) than those without a family history according to a new study. This risk is higher than for women who have parents with diabetes.
Researchers from the University of Michigan Medical School in the US and colleagues studied more than 4500 women taking part in the National Health and Nutrition Examination Survey III (NHANES III) who had previously given birth. They were asked about their family history of diabetes and were classified as having a history of gestational diabetes, diagnosed diabetes or neither.
After adjusting for age and race, compared to women with no family history of diabetes:
· Women who had a mother with diabetes had 3 times the risk of developing GDM
· Women who had a father with diabetes had more than 3 times the risk of developing GDM
· Women who had s sibling with diabetes had more than 7 times the risk of developing GDM
Interestingly, a different pattern was seen for risk of type 2 diabetes, where a parental history increased the risk to a greater extent than having a sibling with diabetes – in fact having both parents with diabetes increased the risk of developing type 2 diabetes around eight-fold.
The researchers suggest that gestational diabetes may follow a different pattern of inheritance than type 2 diabetes and conclude that further investigation of these patterns could help identify women who are at particularly high risk of developing type 2 diabetes after having gestational diabetes.
Kim C, Liu T, Valdez R, et al. Does frank diabetes in first-degree relatives of a pregnant woman affect the likelihood of her developing gestational diabetes mellitus or nongestational diabetes? Am J Obstet Gynecol 2009;201:576.e1-6
November 2009: Male relatives of women with PCOS at risk for Metabolic Syndrome
There is a high prevalence of metabolic syndrome in fathers and brothers of women with polycystic ovary syndrome (PCOS), according to researchers from the Boston University School of Medicine.
Women with PCOS have been found to have twice the risk of the metabolic syndrome compared to the general population, and the risk is also higher in their mothers and sisters. In this study the researchers studied more than 200 fathers and almost 60 brothers of women with PCOS, comparing them to more than 1600 subjects of similar age and race, taking part in a large national study.
The metabolic syndrome, also known as syndrome X or the insulin resistance syndrome, is a collection of symptoms (including raised blood glucose levels, blood fats, blood pressure and carrying weight around the middle) which occur together and can increase the risk of type 2 diabetes, heart disease and stroke.
The researchers found that first-degree male relatives of women with PCOS do indeed have a higher risk of the metabolic syndrome. In fact 42% of fathers and 22% of brothers of women with PCOS had the metabolic syndrome, compared to 32% and 9% of the general population, respectively. Although not the case in women with PCOS and their female relatives, this study found that body mass index (BMI) accounted for the higher risk in male relatives – once they controlled for BMI, the rates were similar to the general population.
The authors conclude, however, that screening for metabolic syndrome should be considered in male first-degree relatives of women with PCOS.
Coviello et al. High prevalence of metabolic syndrome in first-degree male relatives of women with polycystic ovary syndrome is related to high rates of obesity. J Clin Endocrinol Metab 2009;94:4361-4366.
November 2009: Combined diet and exercise the key to improving insulin resistance
Combining diet and exercise, rather than diet or exercise alone, leads to significantly greater improvements in body fat distribution and insulin resistance, according to the findings of a new study. Insulin resistance is the underlying problem in type 2 diabetes and PCOS.
Researchers from the University of Arkansas for Medical Sciences studied 34 obese older men and women who were randomised to one of four groups: the first two groups aimed to lose weight, one through diet (reducing their energy intake) and the second through exercise plus diet. A third group underwent exercise training without weight loss (they ate more to prevent weight loss due to their increased activity) and a fourth group acted as controls. The study was designed so that the two weight loss groups lost a similar amount of weight.
The researchers found that while weight loss was similar in the diet and exercise + diet groups, the latter group lost significantly more visceral fat (also known as abdominal fat, or fat stored around the middle) compared to those who dieted only or the exercise only group. Improvements in insulin resistance were also significantly greater in the exercise + diet group compared to the diet or exercise only groups.
The researchers conclude that a combination of diet and exercise is the optimal intervention for improving body fat distribution and insulin resistance.
Coker et al. The Impact of Exercise Training Compared to Caloric Restriction on Hepatic and Peripheral Insulin Resistance in Obesity. The Journal of Clinical Endocrinology & Metabolism Vol. 94, No. 11 4258-4266
November 2009: Exercise, not genes, predicts body fat levels
We can’t always blame our genes for being overweight according to Finnish researchers – it’s the amount of exercise we get that influences how much fat we carry.
While exercise is thought to reduce body fat levels most studies have only been short-term and many are limited by genetic selection. So these researchers studied 16 middle-aged same-sex twin pairs (both identical and non-identical) who had different physical activity levels (ie one twin was significantly more active than the other) over a 32 year follow-up period. They found that compared to their active siblings, the physically inactive twins had:
· 50% more visceral fat (also know as abdominal fat or fat stored around the middle)
· 170% more liver fat
· 54% more intramuscular fat (fat located throughout muscle)
All three types of fat are considered ‘high risk’, contributing to diabetes and heart disease risk.
The researchers also found that fitness level (measured by peak oxygen uptake) was inversely associated with intramuscular and visceral fat, suggesting that the twins who were fitter were less likely to be carrying excess body fat.
The researchers conclude that regular physical activity appears to be an important factor in preventing the accumulation of high-risk fat over time, even after controlling for genetics and childhood environment. They recommend that the role of regular leisure-time physical activity should be emphasized in the prevention and treatment of obesity.
Leskinen et al. Leisure-time physical activity and high-risk fat: a longitudinal population-based twin study. International Journal of Obesity 2009; 33: 1211–1218
April 2009: Exercise reduces loss of lean muscle during weight loss
Exercising at a moderate or vigorous level during weight loss can reduce the loss of lean muscle tissue associated with dieting but doesn’t affect abdominal fat loss, according to the findings of a new study.
Researchers from the Wake Forest University School of Medicine in the US studied 112 overweight and obese postmenopausal women who were assigned to one of three 20 week interventions:
- Calorie restriction (dieting) only
- Calorie restriction plus moderate-intensity aerobic exercise
- Calorie restriction plus vigorous-intensity aerobic exercise
The exercise involved walking on a treadmill at an intensity of 45-50% (moderate intensity) or 70-75% (vigorous intensity) of heart rate reserve. The study was designed so that the energy deficit (the difference between what they ate and how much energy they used up with exercise) was the same for each group.
Ninety-five women completed the study and lost, on average, 12.1kg over the 20 week study. The researchers found that all groups achieved a similar reduction in abdominal visceral fat – around 25%. However those in the vigorous-intensity group increased their fitness levels (measured by VO2max) to a greater extent and increased fitness levels were related to loss of abdominal fat. They also found that diet only group lost more lean body mass than either exercise group. Loss of lean muscle reduces metabolic rate and can make continued weight loss and maintenance more difficult.
Previous studies have shown similar findings. For example a similar study (comparing diet only versus diet plus exercise over 20 weeks) was recently published involving 94 overweight and obese women with polycystic ovary syndrome (PCOS). Like the study above, both the diet only and exercising groups lost similar amounts of weight (in this study it was 8.7-10.6%) but the researchers found that almost 50% of the weight loss in the diet only group (3.8kg) was due to a reduction in fat free mass. The exercising groups (either aerobic or combined aerobic-resistance training) lost approximately 45% more fat mass and 60% less fat free mass than the diet only group.
Nicklas et al. Effect of exercise intensity on abdominal fat loss during calorie restriction in overweight and obese postmenopausal women: a randomized, controlled trial. Am J Clin Nutr 89: 1043-1052, 2009.
Thomson et al. The effect of a hypocaloric diet with and without exercise training on body composition, cardiometabolic risk profile, and reproductive function in overweight and obese women with polycystic ovary syndrome. J Clin Endocrinol Metab 2008.