Association Between Dietary Whole Grain Intake and Risk of Mortality: Two Large Prospective Studies in US Men and Women | Journal Scan

Study Questions:

What is the association between dietary whole grain consumption and risk of mortality?

Methods:

The authors used the data from two large prospective cohort studies: 74,341 women from the Nurses’ Health Study (1984–2010) and 43,744 men from the Health Professionals Follow-Up Study (1986–2010). All patients were free of cardiovascular disease (CVD) and cancer at baseline.

Results:

A total of 26,920 deaths occurred during 2,727,006 person-years of follow-up. After multivariate adjustment for potential confounders, including age, smoking, body mass index, physical activity, and modified Alternate Healthy Eating Index score, higher whole grain intake was associated with lower total and CVD mortality, but not cancer mortality. The pooled hazard ratios (HRs) for quintiles 1 vs. 5, for whole grain intake were 1 (reference) vs. 0.91 (95% confidence interval [CI], 0.88-0.95) for total mortality (p for trend < 0.001); 1 (reference) vs. 0.85 (95% CI, 0.78-0.92) for CVD mortality (p for trend < 0.001); and 1 (reference) vs. 0.97 (95% CI, 0.91-1.04) for cancer mortality (p for trend = 0.43). They estimated that every serving (28 g/d) of whole grain consumption was associated with a 5% (95% CI, 2%-7%) lower total mortality or a 9% (95% CI, 4%-13%) lower CVD mortality, whereas the same intake level was nonsignificantly associated with lower cancer mortality (HR, 0.98; 95% CI, 0.94-1.02). In a substitution analysis, replacing 1 serving of refined grains or total red meat with 1 serving of whole grains daily was associated with lower CVD mortality: 8% (pooled HR, 0.92; 95% CI, 0.88-0.97) for replacing refined grains and 20% (pooled HR, 0.80; 95% CI, 0.75-0.86) for replacing red meat. Similar inverse associations were observed between bran intake and CVD mortality, but not for germ intake after adjustment for bran intake.

Conclusions:

These data indicate that higher whole grain consumption is associated with lower total and CVD mortality in US men and women, independent of other dietary and lifestyle factors. The results are in line with recommendations that promote increased whole grain consumption to facilitate disease prevention.

Perspective:

The difference between whole grain, germ, and bran is a bit confusing. Any food made from wheat, rice, oats, corn, or another cereal is a grain product. Bread, pasta, oatmeal, and grits are all grain products. There are two main types of grain products: whole grains and refined grains. Whole grains contain the entire grain: the bran, germ, and endosperm. Examples include whole-wheat flour, oatmeal, whole cornmeal, and brown rice. Refined grains (processed carbohydrates) have been milled (ground into flour or meal), which results in the bran and germ being removed. This process removes much of the insoluble fiber, magnesium, B-vitamins, iron, and phytochemicals that consistently have been shown to have beneficial effects on glucose metabolism, lipids, endothelial function, antioxidant activity, and inflammation. Examples of refined grains are wheat flour, enriched bread, and white rice.

Clinical Topics: Prevention, Diet, Smoking

Keywords: Avena sativa, Body Mass Index, Bread, Cardiovascular Diseases, Cereals, Diet, Dietary Fiber, Endosperm, Inflammation, Iron, Life Style, Magnesium, Meat, Motor Activity, Oryza sativa, Phytochemicals, Risk, Smoking, Triticum, Vitamin B Complex, Zea mays


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