Whole-grain intake may reduce the risk of ischemic heart disease death in postmenopausal women: The Iowa women's health study

Background: A recent review of epidemiologic literature found consistently reduced cancer and heart disease rates in persons with high compared with low whole-grain intakes. Objective: We hypothesized that whole- grain intake was associated with a reduced risk of ischemic heart disease (IHD) death. Design: We studied 34492 postmenopausal women aged 55-69 y and free of IHD at baseline in 1986. There were 438 IHD deaths between baseline and 1995. Usual dietary intake was determined with use of a 127-item food- frequency questionnaire. Results: Whole-grain intake in median servings/d was 0.2, 0.9, 1.2, 1.9, and 3.2 for quintiles of intake. The unadjusted rate of IHD death was 2.0/1 x 10³ person-years in quintile 1 and was 1.7, 1.2, 1.0, and 1.4 IHD deaths/1 x 10³ person-years in succeeding quintiles (P for trend < 0.001). Adjusted for demographic, physiologic, behavioral, and dietary variables, relative hazards were 1.0, 0.96, 0.71, 0.64, and 0.70 in ascending quintiles (P for trend = 0.02). The lower risk with higher whole-grain intake was not explained by intake of fiber or several other constituents of whole grains. Conclusion: A clear inverse association between whole-grain intake and risk of IHD death existed. A causal association is plausible because whole-grain foods contain many phytochemicals, including fiber and antioxidants, that may reduce chronic disease risk. Whole-grain intake should be studied further for its potential to prevent IHD and cancer.