Whole Grain, Bran Intake Linked to Lower Mortality in Diabetic Women
By Laurie Barclay, MD
Medscape Medical News
May 11, 2010 — Whole grain and bran intake are linked to lower mortality rates in women with type 2 diabetes, according to the results of a study reported online May 10 in Circulation.
"To my knowledge, this is the first study of whole grain and its components and risk of death in diabetic patients," said senior author Lu Qi, MD, PhD, from Harvard Medical School and Harvard School of Public Health in Boston, Massachusetts, in a news release. "Patients with diabetes face 2 to 3 times the risk of cardiovascular disease and premature death compared to the general population."
As part of the Nurses' Health Study, 7822 US women with type 2 diabetes mellitus completed regularly administered questionnaires evaluating dietary intakes and potential confounders. During follow-up lasting up to 26 years, there were 852 all-cause deaths and 295 cardiovascular deaths.
Compared with the lowest fifths of intakes of whole grain, cereal fiber, bran, and germ, the highest fifths were associated with 16% to 31% lower all-cause mortality rate, after adjustment for age. However, only the association for bran intake remained significant after further adjustment for lifestyle and dietary risk factors (P for trend = .01). Across the fifths of bran intake, the multivariate relative risks were 1.0 (reference), 0.94 (95% confidence interval [CI], 0.75 - 1.18), 0.80 (95% CI, 0.64 - 1.01), 0.82 (95% CI, 0.65 - 1.04), and 0.72 (95% CI, 0.56 - 0.92).
Bran intake was also inversely associated with cardiovascular mortality, with relative risks across the fifths of bran intake being 1.0 (reference), 0.95 (95% CI, 0.66 - 1.38), 0.80 (95% CI, 0.55 - 1.16), 0.76 (95% CI, 0.51 - 1.14), and 0.65 (95% CI, 0.43 - 0.99; P for trend = .04). For added bran alone, findings were similar.
"These findings suggest a potential benefit of whole grain, and particularly bran, in reducing death and cardiovascular risk in diabetic patients," Dr. Qi said.
Limitations of this study include possible uncontrolled and unmeasured confounders, measurement error of dietary intake assessment, insufficient power to detect modest associations, and lack of generalizability to men and nonwhite ethnic groups.
"Diabetes is thought to be a chronic state of inflammation characterized by moderately increased levels of chemical markers for inflammation and endothelial dysfunction," Dr. Qi concluded. "Those markers have been found to be related to increased risk of CVD [cardiovascular disease] in both diabetic and non-diabetic populations. In our previous studies, we have reported that intakes of whole grains and subcomponents such as cereal fiber may lower these markers in diabetic patients."
The National Institutes of Health, the American Heart Association Scientist Development Award, and the Boston Obesity Nutrition Research Center supported this study. The study authors have disclosed no relevant financial relationships.
