Whole grains, bran and germ and risk of CHD in men

Nutrition Research Newsletter, Jan, 2005

Intake of whole grains is associated with a reduced incidence of fatal and nonfatal coronary heart disease (CHD) in many large population studies. Whole grains are rich in nutrients that are related to beneficial health effects in observational studies. Components such as fiber, vitamin E and B-6, minerals, antioxidants and phytoestrogens are found in the bran and germ components of whole grains. Because bran and germ can easily be added to food during processing or cooking, it is important to consider whether they contribute to the reduced CHD risk independently or whether whole grain products yield a greater benefit than do the sum of the parts.

Most studies use a definition of whole-grains developed by Jacobs et al., which states that a single serving of dark bread, brown rice, popcorn, wheat germ, bran, cooked oatmeal, bulgur, couscous and breakfast cereals with a whole-grain or bran content >25% by weight are classified equally as whole-grain products. In the Health Professionals Follow-Up Study, a new whole-grain food composition database was also developed. The current study evaluated the association of whole-grain, bran and germ intakes (with the use of the aforementioned new quantitative measures) with the incidence of CHD.

Data from the Health Professionals Follow-Up Study was used and included 42,850 male health professionals aged 40 to 75 years at baseline in 1986, who were free from cardiovascular disease, cancer, and diabetes. Nonfatal myocardial infarction and fatal CHD occurring between 1986 and January 31,2000 were considered endpoints. Dietary information was collected with a validated semi-quantitative FFQ.

During the 14-year follow-up period, 1,818 incident cases of CHD were documented. Cold breakfast cereals were the largest source of whole grains contributing 33% of total intake. Compared with men in the lowest quintiles of wholegrain intake, the hazard ratio (HR) for risk of overall CHD was 0.64 among men in the top quintile. The FIR of CHD in men with the highest intake of added bran was 0.70 compared with men with no intake of added bran. In general, the intake of supplemental germ was very low and added germ was not associated with CHD risk.

The data show an inverse relation between the intake of whole grains and bran with CHD risk. One of the limitations of this study is that it cannot rule out the possibility of confounding variables from reported lifestyle characteristics or the existence of an unmeasured factor associated with high intakes of whole grain being responsible for the reduction in CHD. However, given the specificity of the findings and previous reports, whole grains should be considered an important modifiable risk factor for CHD, and further studies should investigate the additional benefit from the bran and germ components of whole grains.

Majken K Jensen, Pauline Koh-Banerjee, Frank B Hu, et al., Intakes of whole grains, bran, and germ and the risk of coronary heart disease in men, Am J Clin Nutr 80:1492-1499 (December 2004) [Reprints not available. Address correspondence to EB Rimm, Department of Nutrition, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115. E-mail: erimm@hsph.harvad.edu]