High-fiber diet may reduce risk for type 2 diabetes

A diet that is rich in cereal and vegetable fiber, but not fiber from fruit sources, may lower the risk for developing type 2 diabetes, according to research published in Diabetologia.

In a large European cohort study, researchers found that the association between fiber intake and diabetes risk may be partially explained by body weight, whereas a meta-analysis of prospective studies completed worldwide showed that a high-fiber diet reduced the risk for diabetes independent of BMI.

“The current findings are consistent with previous research which have shown an inverse association between intake of whole grains and type 2 diabetes risk,” Dagfinn Aune, a PhD student affiliated with the Norwegian University of Science and Technology and Imperial College London, told Endocrine Today. “So the take-home message would be that people can reduce their risk of type 2 diabetes by increasing the intake of fiber through fiber-rich cereals and whole grain products.”

Dagfinn Aune

Dagfinn Aune

leen Kuijsten, PhD, of Wageningen University in the Netherlands, and colleagues at other institutions analyzed data from the European Prospective Investigation into Cancer and Nutrition (EPIC)-InterAct study, a multicenter, prospective cohort study designed to investigate food habits, lifestyle and environmental factors, and the incidence of cancer and other chronic diseases, including type 2 diabetes, in eight European countries. The cohort included 11,559 participants with type 2 diabetes; a random subcohort included 15,258 participants (including 729 participants with incident diabetes) for comparison.

Researchers analyzed the associations between total fiber, as well as fiber from cereal, fruit and vegetable sources, and new-onset type 2 diabetes. Researchers divided the study participants into four equal-sized groups from lowest to highest fiber intake and assessed their risk for developing type 2 diabetes during an average of 10.8 years of follow-up.

Participants with the highest total fiber intake (more than 26 g/day) had an 18% lower risk for developing diabetes compared with those with the lowest total fiber intake (less than 19 g/day), after adjusting for lifestyle and dietary factors. However, the risk disappeared once researchers adjusted for BMI.

Participants with the highest levels of cereal fiber had a 19% lower risk for developing diabetes compared with those with the lowest consumption levels (HR = 0.81; 95% CI, 0.7-0.93), whereas those with the highest levels of vegetable fiber had a 16% lower risk for developing the disease (HR = 0.84; 95% CI, 0.74-0.96). The associations became nonsignificant after adjustment for BMI, according to researchers.

Fruit fiber was not associated with a reduction in diabetes risk, according to researchers.

Researchers also completed a meta-analysis of pooled data from the EPIC-InterAct study with those from 18 other independent studies, which included 41,066 new-onset cases of type 2 diabetes. In that analysis, data showed the risk for diabetes fell by 9% for each 10 g/day increase in total fiber intake, and by 25% for each 10 g/day increase in cereal fiber intake, independent of BMI. Researchers did not find a statistically significant relationship between increasing either fruit or vegetable fiber and reducing diabetes risk in the meta-analysis.

Aune said dietary fiber may affect diabetes risk in several ways.

“Taken together, our results indicate that individuals with diets rich in fiber, in particular cereal fiber, may be at lower risk of type 2 diabetes,” Aune said in a press release. “We are not certain why this might be, but potential mechanisms could include feeling physically full for longer, prolonged release of hormonal signals, slowed down nutrient absorption, or altered fermentation in the large intestine. All these mechanisms could lead to a lower BMI and reduced risk of developing type 2 diabetes.

“As well as helping keep weight down, dietary fiber may also affect diabetes risk by other mechanisms – for instance, improving control of blood sugar and decreasing insulin peaks after meals, and increasing the body’s sensitivity to insulin,” Aune said. – by Regina Schaffer

The researchers report no relevant financial disclosures.

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