Gluten-free diets may be linked to increased type 2 diabetes risk

Frequent consumption of gluten may be associated with a lower risk for type 2 diabetes, according to research presented at the American Heart Association’s Epidemiology and Prevention / Lifestyle and Cardiometabolic Health 2017 Scientific Sessions in Portland, Oregon.

“Gluten-free diets have grown in popularity, but evidence is lacking regarding gluten intake and long-term health,” Geng Zong, PhD, of Harvard TH Chan School of Public Health in Boston, and colleagues wrote.

“We wanted to determine if gluten consumption will affect health in people with no apparent medical reasons to avoid gluten,” Zong said in a press release. “Gluten-free foods often have less dietary fiber and other micronutrients, making them less nutritious and they also tend to cost more. People without celiac disease may reconsider limiting their gluten intake for chronic disease prevention, especially for diabetes.”

Zong and colleagues evaluated the gluten intake of participants enrolled in the Nurses’ Health Study (NHS; n = 69,276), NHSII (n = 88,610) and the Health Professionals Follow-Up Study (HPFS; n = 41,908) using a validated food-frequency questionnaire that was collected every 2 to 4 years. The researchers defined incident type 2 diabetes as physician-diagnosed diabetes.

The mean gluten intake was 5.83 grams per day in NHS, 6.77 grams per day in NHSII and 7.06 grams per day in HPFS. Gluten intake was strongly associated with consumption of carbohydrate sources, particularly refined grains, starch and cereal fiber. The researches confirmed 15,947 cases of type 2 diabetes over 4.24 million years of follow-up. They noted that pastas, cereals, pizza, muffins, pretzels and bread were major dietary sources.

After multivariate adjustment, all three cohorts demonstrated an inverse association between gluten intake and type 2 diabetes. When comparing extreme quintiles, the hazard ratio was 0.8 (95% CI, 0.76-0.84). After further adjusting for cereal fiber, the associations slightly decreased (HR = 0.87; 95% CI, 0.81-0.93); however, this was not observed when adjusting for other carbohydrate sources. In participants aged younger than 65 years without major chronic diseases, there was no significant association between changes in gluten intake and weight gain. Four-year weight change was 0.08 lb (95% CI, –0.06 to 0.22), –0.05 lb (95% CI, –0.18 to 0.08) and 0.36 lb (95% CI, 0.24- 0.96) for each 5 g increase in gluten intake in NHS, NHSII and HPFS, respectively.

Further investigations are warranted, as gluten intake was self-reported by participants and the study was observational, according to the press release.

“Our findings suggest that gluten intake may not exert significant adverse effects on the incidence of [type 2 diabetes] or excess weight gain,” Zong and colleagues concluded. “Limiting gluten from diet is thus unlikely to facilitate [type 2 diabetes] prevention and may lead to reduced consumption of cereal fiber or whole grains that help reduce diabetes risk.” – by Alaina Tedesco

Reference:

Zong G, et al. Abstract 11. Presented at: American Heart Association’s Epidemiology and Prevention/Lifestyle and Cardiometabolic Health Scientific Sessions; March 7-10, 2017; Portland, Ore.

Disclosure: The researchers report no relevant financial disclosures.