Fat facts and fat fiction.
Dietary advice about fat is always controversial, and even experts disagree about what recommendations are supported by current evidence. Kevin Lomangino, editor of Clinical Nutrition Insight contributed to the recent US Consumer Reports piece (which was also extensively edited and reviewed by nutrition scientists). In a Guest Post on Dr Yoni Freedhof’s blog, Weighty Matters, he provides more detail and links to the evidence that the authors of the Consumer Reports piece considered. ‘Although I don’t harbor any illusions about changing people’s strongly held beliefs about food, I do believe that our recommendations are sound and were based on the best scientific evidence available’ writes Kevin. Check out the state of the evidence on fats HERE.
Does sugar cause diabetes?
A new study in Plos One reports an association between global sugar availability and diabetes prevalence. Despite the headline hype, this study does not in fact provide any strong new evidence that sugar causes type 2 diabetes. Many other better designed studies already provide much stronger evidence that sugar does in fact not cause diabetes. The GI and GL are much more powerful predictors of type 2 diabetes risk.
What sort of study is this? It is an ecological study that examines the role of global sugar availability (using FAOStat data) in the diabetes (using IDF data) and obesity (using WHO data) epidemic. It covers a relatively short time frame of 10 years (2000– 2010) given it uses prevalence rates (not incidence rates – or new cases). Why does that matter? Well, ecological studies like this can show an association. Only randomised controlled trials can prove causality.
What did the study find? The analysis found a small (1.1% increase) but statistically significant association between sugar availability (kilojoules from sugar) and prevalence of diabetes. However, obesity was a much more powerful predictor of diabetes prevalence than sugar availability. Sugar availability was not associated with obesity prevalence. The authors attempted to control for differing definitions of obesity in people from different ethnic backgrounds by using a BMI greater than 25 (overweight in Western populations) as the cut off. But, overweight in many ethnic groups (e.g. Asian or Indian) is defined as a BMI greater than 23, as metabolic disturbance occurs at much lower BMI levels in these ethnic groups than in Western populations. To further confound the results, the researchers did not include other useful body composition measures like waist circumference in their model. When it comes to diabetes, where you carry excess weight really does matter as readers of GI News will know.
What is missing? The study does not discuss any data from the many cohort studies that have found either no association between sugar intake and diabetes risk or a negative association – increased sugar consumption associated with decreased risk of developing type 2 diabetes. If the aim of the paper was to have a balanced discussion of the role of sugar in the development of type 2 diabetes, then the authors should have included evidence from these types of studies in their discussion as it is more powerful than evidence from ecological studies.
What’s the bottom line? Good evidence from systematic reviews of randomized controlled trials show that the best way to reduce the risk of developing type 2 diabetes is to consume 2000-2500 less kilojoules (500-600 calories) each day by eating less fat, and in particular to reduce the intake of saturated fat and increase the intake of dietary fibre. Of course, some people may also reduce their energy intake by reducing the amount of added sugars that they consume.
Vegetarianism can reduce risk of heart disease by a third.
The risk of hospitalisation or death from heart disease is 32% lower in vegetarians than people who eat meat and fish, according to a new study in the American Journal of Clinical Nutrition. ‘Most of the difference in risk is probably caused by effects on cholesterol and blood pressure, and shows the important role of diet in the prevention of heart disease,’ says lead author Dr Francesca Crowe.
The analysis looked at almost 45,000 volunteers from England and Scotland enrolled in the European Prospective Investigation into Cancer and Nutrition (EPIC)-Oxford study, of whom 34% were vegetarian. The volunteers were tracked until 2009, during which time researchers identified 1235 cases of heart disease. They found that vegetarians had lower blood pressure and cholesterol levels than non-vegetarians, which is thought to be the main reason behind their reduced risk of heart disease. Vegetarians typically also had a lower BMI and fewer cases of diabetes, although these were not found to significantly affect the results. Adjusting the results to exclude the effects of BMI, vegetarians remained 28% less likely to develop heart disease. – Eurekalert
A meaty risk factor for gestational diabetes?
‘Whether you are pregnant or trying to conceive, good nutrition is an essential part of optimising your own health and that of your unborn baby. Eating well prior to conceiving ensures your body is in the best position to support a pregnancy, while good nutrition during pregnancy is essential to provide the nutrients your baby needs to grow and develop and those you need to stay healthy during your pregnancy,’ writes Prof Jennie Brand-Miller in The Bump to Baby Diet. A new study just published in Diabetes Care reports that having higher intakes of animal protein, particularly red meat, was significantly associated with a greater risk of gestational diabetes. By contrast, substituting some healthy protein sources such as poultry, fish, legumes and especially nuts was associated with a lower risk. Commenting on this study, Prof Brand-Miller reminds us that: ‘observational studies like this don't prove cause and effect. It’s possible that this finding is confounded to some degree by the fact that women who eat a lot of red meat ALSO live a lifestyle that increases their risk of gestational diabetes – for example they may be women who don't like fruit and veggies, love salty food and rarely if ever exercise.’
Neanderthal medics? Evidence for food, cooking and medicinal plants.
New research confirms ‘the varied and selective use of plants by Neanderthals’ says Professor Les Copeland from the University of Sydney. Until recently Neanderthals, who disappeared between 30,000 and 24,000 years ago, were thought to be predominantly meat-eaters. However, evidence of dietary breadth is growing as more sophisticated analyses are undertaken. Researchers from Spain, the UK and Australia combined pyrolysis gas-chromatography-mass spectrometry with morphological analysis of plant microfossils to identify material trapped in dental calculus (calcified dental plaque) from five Neanderthals from the north Spanish site of El Sidrón. Their results provide another twist to the story – the first molecular evidence for medicinal plants being used by a Neanderthal individual.
In the ten samples of dental calculus from five Neanderthals selected for this study, the researchers found chemical evidence consistent with wood-fire smoke, a range of cooked starchy foods, two plants known today for their medicinal qualities, and bitumen or oil shale trapped in the dental calculus. Evidence for cooked carbohydrates is confirmed by both the cracked/roasted starch granules observed microscopically and the molecular evidence for cooking and exposure to wood smoke or smoked food in the form of a range of chemical markers including methyl esters, phenols, and polynuclear aromatic hydrocarbons found in dental calculus.
The researchers say the starch granules and carbohydrate markers in the samples, plus evidence for plant compounds such as azulenes and coumarins, as well as possible evidence for nuts, grasses and even green vegetables, argue for a broader use of ingested plants than is often suggested by stable isotope analysis. According to lead author Karen Hardy: ‘The varied use of plants we identified suggests that the Neanderthal occupants of El Sidrón had a sophisticated knowledge of their natural surroundings which included the ability to select and use certain plants for their nutritional value and for self-medication. While meat was clearly important, our research points to an even more complex diet than has previously been supposed.’
Earlier research had shown that the Neanderthals in El Sidrón had the bitter taste perception gene. Now trapped within dental calculus researchers found molecular evidence that one individual had eaten bitter tasting plants. ‘The evidence indicating this individual was eating bitter-tasting plants such as yarrow and camomile with little nutritional value is surprising. We know that Neanderthals would find these plants bitter, so it is likely these plants must have been selected for reasons other than taste’ says co-author Dr Stephen Buckley.
The Longevity Project.
This book is a fascinating addition to the burgeoning longevity bookshelf. The authors draw on an eight-decade-long Stanford University study tracing the lives of 1500 people (the Terman study) to find who lives a long, healthy life and why. If there’s a secret to old age, they report, it’s living conscientiously and bringing forethought, planning, and perseverance to your professional and personal life. Here’s an extract from the introduction to whet your appetite.
‘Most books about health and longevity are cookbooks – literally or figuratively. When they aren’t giving you recipes (start Week 1 with spinach sautéed in garlic and olive oil) and food lists (an apple a day), they’re offering a list of dos and don’ts (do exercise for 30 minutes four times a week; don’t let your weight rise above a certain ratio to your height).
Exercise, diet, stress, and weight are indeed relevant to health, but in ways that vary from person to person. Lists of dos and don’ts are nearly impossible for most of us to follow for days, months, and years. Thankfully, the Terman study participants showed us that struggling with lists of specific health rules is unnecessary. The Terman men and women were born decades before running shoes, designer spas, and fancy medical tests were invented, yet many lived long, healthy lives. The point of describing our findings is not to lay out the factors that are likely to leave you the last one standing. Most of us, after all, would not wish to live extra years if they were years of constant decline and pain. But the fact is, those who live longer are also generally healthier throughout their lives. Most people who live to old age do so not because they have beaten cancer, heart disease, diabetes, or lung disease; rather, the long-lived have mostly avoided serious ailments altogether.
Because Dr. Terman began studying his participants when they were very young, many of the insights that emerged are helpful not only to adults looking to get on a healthier life path but also to those hoping to set their children on a good track. Many of our findings can help people rethink the potential long-term effects of their parenting decisions, as well as promote their whole family’s future health, happiness, and well-being.’ – The Longevity Project is available online and from good bookshops.
1 March 2013
Fat facts and fat fiction.
Posted by GI Group at 1:06 am