Got gluten? You should. A recent study suggests that going “gluten-free” may raise your risk for Type 2 diabetes. The diet, meant for a small population of individuals who have Celiac disease or gluten intolerance, became popular despite lack of evidence that it was healthy for most people. Gluten is a protein found in wheat, rye and barley that gives baked goods their texture. A small percentage of people with celiac disease may also need to avoid oats due to a protein sensitivity.
According to Dr. Geng Zong from the Harvard University Dept. of Nutrition T.H. Chan School of Public Health, gluten-free foods are often less nutritious because they lack dietary fiber as well as vitamins and minerals. They tend to be more expensive. His study looked at health effects of a gluten-free diet on subjects that did not medically need to follow one. In a long term longitudinal study, scientists observed that most subjects consumed 12 grams of gluten or less per day. In those that consumed higher amounts of gluten, the risk of type 2 diabetes over a 30-year span, was lower. Cereal fiber intake was lower in subjects on a gluten-free diet, which is important to note as it is a protective component for development of type 2 diabetes. After accounting for the effect of cereal fiber, those in the highest 20% of gluten ingestion experienced a 13% lower risk of diabetes development than those with the lowest intake of gluten (< 4 grams).
In three other large, long term Nurse’s Health studies (NHS and NHS II) and the Health Professionals follow up study, gluten intake was gathered using food frequency questionnaires. The average gluten intake was between 5.8 to 7.1 grams per day, which came primarily from pretzels, bread, pizza, muffins, cereal and pasta. Data was observational as subjects self-reported their gluten intake. In over 4.24 million person years of follow up over 1984-1990 to 2010-2013, 15,947 cases of Type 2 diabetes were identified. Gluten-free diets were not popular at the time, so information on gluten abstainers was not available.
The bottom line is that if you don’t need a gluten-free diet, don’t follow it. Include gluten-containing, high fiber, whole grains in your diet daily. The US Dietary Guidelines advise 20-25 grams of dietary fiber per day for women and 35-38 grams per day for men. Below is a list of whole grains and their fiber content:
Barley (1/2 cup cooked): 3.1 grams
Bran cereal (3/4 cup): 5.9 grams
Brown rice (1/2 cup cooked): 2 grams
Bulgur (1/2 cup cooked): 4.1 grams
Oatmeal (1/2 cup cooked): 4.1 grams
Rye bread (1 slice): 1.5 grams
Quinoa (1/2 cup cooked): 2.75 grams
Whole wheat bread (1 slice): 3 grams
Whole grain pasta (1/2 cup cooked): 5-6 grams
Geng Zong, Ph.D., research fellow, department of nutrition, Harvard T.H. Chan School of Public Health, Boston; Lauri Wright, Ph.D., R.D.N., spokesperson, Academy of Nutrition and Dietetics, and director, doctorate in clinical nutrition program, University of North Florida, Jacksonville; March 9, 2017 presentation, American Heart Association Epidemiology and Prevention/Lifestyle and Cardiometabolic Health 2017 Scientific Sessions, Portland, Ore.