Carb-rich diets increase diabetes risk in women, but cereal fiber may lower risk

Carbohydrate-rich and high glycemic index diets are associated with an increased risk of developing type 2 diabetes in Chinese and black women, whereas adding cereal fiber to the diet may protect against diabetes in black women, according to two studies published Nov. 26 in the Archives of Internal Medicine.

Raquel Villegas, PhD, of Vanderbilt University Medical Center in Nashville, TN, and colleagues followed 64,227 Chinese women for nearly 5 years, interviewing the women periodically about dietary habits. Dietary carbohydrate and rice intake were associated with an increased risk of type 2 diabetes, with a relative risk of 1.28 for carbohydrates and 1.78 for rice for women in the highest versus lowest quintiles of intake.

In a second study, Supriya Krishnan, of Boston University, and colleagues surveyed 40,078 black women in the United States regarding dietary habits and followed them for 8 years. Among women with a body mass index less than 25, a glycemic index in the highest quintile carried almost twice the risk of developing diabetes, while cereal fiber intake in the highest quintile decreased the risk by 59% compared to those in the lowest quintiles.

“A simple change from white bread (two slices provides 1.2 g of fiber) to whole wheat bread (two slices provides 3.8 g of fiber) or substituting a cup of raisin bran (5.0–8.0 g of fiber) or oatmeal (4.0 g of fiber) for a cup of corn chex (0.5 g of fiber) or rice chex (0.3 g of fiber) will move a person from a low fiber intake category to a moderate intake category, with a corresponding 10% reduction in risk,” Krishnan and colleagues write.

Villegas R, Liu S,  Gao YT, et al. Prospective study of dietary carbohydrates, glycemic index, glycemic load, and incidence of type 2 diabetes mellitus in middle-aged Chinese women. Arch Intern Med. 2007;167:2310-2316.

Krishnan S, Rosenberg L, Singer M, et al. Glycemic index, glycemic load, and cereal fiber intake and risk of type 2 diabetes in US black women. Arch Intern Med. 2007;167:2304-2309.