Abstract 18: Whole Grain Intake and Risk of All-Cause and Cause-Specific Mortality in US Men and Women

Abstract

Background: Whole grains are rich in fiber, vitamins, minerals, and antioxidants that have favorable effects on health through multiple pathways. Although epidemiologic studies have suggested that whole grain intake may reduce risk of type 2 diabetes, hypertension and cardiovascular disease (CVD), limited evidence exists regarding whole grains’ associations with mortality in prospective studies. Methods: Whole grain consumption was measured using a validated food frequency questionnaire every 2-4 years among 74,341 women in the Nurses’ Health Study (1984-2010) and 43,990 men in the Health Professionals Follow-Up Study (1986-2010) who were free of CVD, diabetes, and cancers at baseline. Intake of whole grain foods including brown rice, dark breads, whole-grain ready-to-eat cereals, cooked cereal, popcorn, wheat germ, bran and other grains. We used the cumulative average of whole grain intake from all available dietary questionnaires from baseline through the end of follow-up were used to better represent long-term or habitual intake, and to minimize within-person variation. Cox regression models were used to evaluate the associations between whole grain intake and mortality. Results: We documented 26,918 deaths in these two cohorts during 2,731,264 person-years of follow-up through 2010. After multivariate adjustment for potential confounders, including age, smoking, BMI, physical activity, and alternate healthy eating index, the hazard ratios (HRs) of total mortality comparing the highest with the lowest quintile of whole grain intake was 0.89 (95% confidence interval [CI] 0.84, 0.94, P for trend < 0.0001) in NHS and 0.92 (95%CI 0.87, 0.98, P for trend = 0.01) in HPFS; and the pooled HR was 0.91 (95% CI 0.85, 0.95). An inverse association was observed for CVD mortality: the pooled HRs (95% CIs) comparing extreme quintiles were 0.85 (95%CI 0.78, 0.92, P for trend < 0.0001). Whole grain intake was not significantly associated with cancer mortality, the pooled HR was 0.98 (95% CI 0.91, 1.04, P for trend = 0.49). In addition, total bran intake was observed to be significantly inversely associated with CVD mortality, with pooled HR 0.80 (95% CI 0.73, 0.87, P for trend < 0.0001), while total germ intake was not associated with risk of mortality after adjustment for bran intake. These associations did not change materially among men and women who had a healthful lifestyle or diet. In sensitivity analysis, to minimize reverse causation, we used a 4-year lagged analysis or further stopped updating diet after participants reported occurrence of hypertension and high cholesterol, and all these sensitivity analysis indicated the robustness of our results. Conclusions: Our data support the hypothesis that higher whole grain consumption may have beneficial effects on lowering total and CVD mortality in US men and women.