SEARCH HEALTH STUDIES

Gluten Not Related to Heart Disease, but Avoiding Whole Grains Is

Unless you have celiac disease, you might want to rethink that gluten-free diet. In a study of more than 100,000 US adults without celiac disease, followed for more than 25 years, researchers found that eating gluten was not related to heart disease risk. In fact, the researchers caution that avoiding gluten may result in eating fewer whole grain foods, which may in turn pose a risk for heart disease.
BMJ. 2017 May 2;357:j1892. (Lebwohl B et al.)

Few Patients with Suspected Non-celiac Gluten Sensitivity Actually Show Gluten-Specific Symptoms

Many patients who respond well to a gluten free diet, but don’t test positive for celiac disease, are thought to have non-celiac gluten sensitivity. However, a closer look at this population is raising some doubts. Researchers in Spain analyzed data from 10 studies comprising 1312 adults, all of which were double blind, placebo controlled gluten challenges (meaning that neither the researchers nor the participants knew if they were getting a gluten-free diet or the gluten-containing placebo).  Only 16% of the non-celiac gluten sensitivity patients showed gluten-specific symptoms when exposed to the gluten-containing diet, and 40% of them had similar or increased symptoms when on the gluten-free control diet. The researchers conclude that these results “cast doubt on gluten as the culprit food component in most patients with presumptive [non-celiac gluten sensitivity].”  
Perspectives in Clinical Gastroenterology and Hepatology. 2017 Mar:15(3):339-348. (Molina-Infante J et al.) 

Healthy Diets (Such as Mediterranean Diet) Linked with Better Sperm Quality

For couples trying to get pregnant, a healthy diet may help tilt the odds in their favor. To see what types of foods are associated with better male fertility and healthy sperm quality, researchers analyzed data on eating patterns and male fertility in 35 observational studies from around the world. They found that a healthy diet (e.g. a Mediterranean diet) with lots of seafood, poultry, vegetables, fruits, low fat dairy, and grains is associated with better sperm quality. They also found that in some studies, processed meat, soy foods,  potatoes, full fat dairy, coffee, alcohol, sugary drinks, and sweets were linked with poor sperm quality and male infertility.
Human Reproduction Update. 2017 Mar 10:1-19. (Salas-Huetos A et al.)

Low Gluten Diet Linked with Diabetes

For those without a medically diagnosed gluten issue (such as celiac disease), the support for gluten-free and low-gluten diets appears to be more fad than fact. In a study of nearly 200,000 health professionals, researchers at Harvard found that eating lower amounts of gluten is related to a higher risk for type 2 diabetes. In fact, those in the top 20% of gluten intake were 13% less likely to get type 2 diabetes over the 30-year study period, even after adjusting for family history, exercise habits, weight, and calorie intake. (Note that research presented at meetings is considered preliminary until published in a peer reviewed journal.)
Presented at the American Heart Association’s Epidemiology and Prevention / Lifestyle and Cardiometabolic Health 2017 Scientific Sessions. Portland, OR. March 9, 2017. (Zhong G et al.)

Inadequate Vegetables, Fruits, Whole Grains, Omega 3’s Linked with Cardiometabolic Death

Researchers created models to estimate the percentage of US cardiometabolic deaths (deaths from heart disease, stroke, or type 2 diabetes), that can be attributed to specific aspects of a poor diet. After analyzing decades of eating pattern data from large, nationally representative surveys (NHANES), the researchers estimated that nearly half of all cardiometabolic deaths can be attributed to poor diet. Specifically, they found that high sodium diets, low nut & seed intake, high intake of processed meats (like sausage or bacon), low seafood omega-3 fats, low vegetable intake, low fruit intake, high intake of sugar sweetened beverages (like soda), and low intake of whole grains contributed the most to cardiometabolic deaths, at about 5.9-9.5% each. The researchers note that the importance of eating more healthy foods (like whole grains or vegetables) is very important, in addition to decreasing less healthy foods (like soda or bacon).
JAMA. 2017 Mar 7;317(9):912-924. (Micha R et al.)

Whole Plant Foods, Not Fads, Best for Heart Health

Magazines and news articles often jump from one “superfood” or fad diet to the next, but not all nutrition advice is backed up by substantial evidence. In this review, researchers analyzed the scientific support for various trending “heart healthy” foods and diets. Eating berries, nuts, extra virgin olive oil, leafy green vegetables, and plant-based diets are all strongly linked with better heart-health based on numerous studies. On the other hand, coconut oil, palm oil, eggs, juicing, and southern diets are linked with potential harm. Additionally, the researchers found no support that gluten-free diets are beneficial for people without gluten related disorders. The authors conclude that “Evidence-based healthy dietary patterns are high in fruits, vegetables, whole grains, legumes, and nuts in moderation, although some may include limited quantities of lean meats (including poultry and seafood), low-fat dairy products, and liquid vegetable oils.”
Journal of the American College of Cardiology. 2017 March 7;69(9):1172-87.

Healthier Diet May Reduce Greenhouse Gas Emissions & Cut Healthcare Costs

Healthy diets nourish both people and the planet, and the savings can be quite impressive. Scientists in California created models to analyze how greenhouse gas emissions and healthcare costs might change if we decrease red & processed meat and refined grains in our standard US diet, and shift to eat more beans and peas, whole grains, fruits, and vegetables. The researchers found that opting for the healthier diets can reduce risk of heart disease, colorectal cancer, and type 2 diabetes by 20-40%, saving the US $77-93 billion per year in healthcare. These shifts can also lower greenhouse gas emissions by 222-826 kg CO2, which is equivalent to 6-23% of the US Climate Action Plan’s target. Climatic Change. 2017 Mar 6. [Epub] (Hallstrom E et al.)

Mediterranean Diet Linked with up to 40% Lower Risk of Breast Cancer

About ⅓ of breast cancer cases are hormone-receptor-negative, meaning that they are unlikely to respond to hormonal therapy. To see if diet relates to breast cancer risk, researchers analyzed the eating habits and health outcomes of more than 62,500 post-menopausal Dutch women for about 20 years. Those most closely following a Mediterranean diet were 40% less likely to develop estrogen-receptor-negative breast cancer, although overall breast cancer risk and the risk for other types of breast cancer were not significantly lower. Nut intake was the only food significantly associated with a lower risk of estrogen-receptor-negative breast cancer. For total and estrogen-receptor positive breast cancer, whole grain intake contributed the most to the lower risk, although not significantly.
International Journal of Cancer. 2017 Mar 5. [Epub ahead of print] (van den Brandt PA).

Grain-Free Diets Linked with Overweight & Obesity & Less Fiber, Fruits & Vegetables

Grains have been at the core of traditional diets for millennia, but some misguided celebrities and fad diets have moved away from this tradition. Using national health survey data from 9,341 adults in Australia, researchers found that those avoiding core grain foods were significantly more likely to be overweight or obese than those who eat grains, despite consuming fewer calories, fruits, vegetables and less fiber than grain eaters. After adjusting for age, sex, and calorie intake, avoiding grains was also linked with a higher BMI and waist size.
Nutrients. 2017 Feb 18;9(2). pii: E157. (Fayet-Moore F et al.)

Whole Grains May Help Your Body Burn More Calories

Whole grains are often associated with lower body weights, and new research is uncovering why. In a randomized trial, scientists assigned 81 healthy adults in Boston to diets with either whole grains or refined grains for 6 weeks, keeping all other foods and nutrients consistent between the groups. Although the diets were designed to be isocaloric (meaning that people were supposed to maintain their same body weight), the resting metabolic rate (how many calories your body burns at rest) became significantly higher (by 43 calories) in the whole grain group. In fact, the whole grain group significantly improved their metabolism over the 6-week study compared with the refined grains group, burning 92 more calories per day. The researchers suspect that this is partly due to the fact that the whole grain group excreted more energy in the stool, and had more frequent bowel movements.
American Journal of Clinical Nutrition. 2017 Feb 8. pii: ajcn139683. [Epub ahead of print.] (Karl JP et al.)

Whole Grains Can Improve Gut Microbiota

Researchers randomly assigned 81 healthy adults in Boston to diets with either whole grains or refined grains for 6 weeks, keeping all other foods and nutrients consistent between the groups. The researchers found that making all of your grains whole is linked with “modest, positive effects on gut micriobiota,” (due to higher concentrations of “good” gut microbes and short chain fatty acids – an indicator of colon health and dietary fiber breakdown) as well as increased stool weight and stool frequency.
American Journal of Clinical Nutrition. 2017 Feb 8. pii: ajcn146928. [Epub ahead of print.] (Vanegas SM et al.)

Whole Grains & Fiber Linked with Less Colorectal Cancer

Because colorectal cancer forms in the large intestine, diet is thought to be a potential risk factor. To see how food fits into the puzzle, scientists at Harvard analyzed the eating patterns and health markers of 137,217 adults for more than two decades. Those eating a healthy diet rich in fiber and whole grains were significantly less likely to develop a certain type of colorectal cancer (Fusobacterium nucleatum–positive, but not Fusobacterium nucleatum-negative) than those eating a “Western diet” rich in red meat, refined grains, and dessert. Fusobacterium nucleatum is a type of gut bacteria thought to contribute to colorectal cancer, as it’s often elevated in colorectal cancer patients. Based on their findings, the scientists suspect that the cancer-protective effect of fiber and whole grains may have to do with their role in improving the gut microbiome.
JAMA Oncology.  2017 Jan 26. [Epub ahead of print.] (Mehta RS)

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