WESTPORT, Sep 01 (Reuters Health) - Increasing consumption of whole-grain foods reduces the risk of type 2 diabetes mellitus in women, according to the results of a large, prospective study. This effect is not completely explained by dietary fiber, magnesium, and vitamin E content, suggesting that other characteristics of whole grains are important in protecting against diabetes.

Dr. Simin Liu, of Harvard Medical School, in Boston, Massachusetts, and associates analyzed prospectively collected data from 75,521 participants in the Nurses' Health Study from 1984 to 1994. During this time there were 1879 incident cases of type 2 diabetes mellitus. These findings are reported in the September issue of the American Journal of Public Health.

When the investigators compared subjects with the highest and lowest quintiles of whole-grain intake, the relative risk for type 2 diabetes mellitus was 0.62. For refined grain intake, the relative risk was 1.31.

After adjusting for age and total energy intake, increasing ratios of refined- to whole-grain intake were associated with increased risk of type 2 diabetes, with those in the highest quintile at 57% greater risk for the disease than those in the lowest quintile.

The associations remained significant after adjusting for "body mass index, cigarette smoking, alcohol intake, history of diabetes in first-degree relative, use of multivitamins, use of vitamin E supplements, physical activity, and total energy intake."

Most of the individual foods contributing to whole-grain intakes--dark bread, whole-grain breakfast cereal, brown rice, wheat germ, bran, and other grain--were also inversely associated with type 2 diabetes after adjusting for the same covariates.

"Something present in whole grains may be responsible for the observed protective effect, even though the nutrient content of different whole-grain products may vary," Dr. Liu and colleagues state. This is supported by their finding that the inverse association was evident even after accounting for dietary fiber, magnesium, and vitamin E in multivariate models.

"Other antioxidants, nutrients, or phytochemicals in whole grains or interactions among them also may play important roles in risk reduction," the investigators conclude.

(From ReutersHealth)