The benefits from eating whole-grain foods go way beyond dietary fiber alone. Whole-grain foods, like whole-wheat bread, oatmeal and brown rice, are also rich in B vitamins, vitamin E, iron and antioxidants. Most importantly, a diet rich in whole-grain foods has been linked to reducing the risk of diabetes and coronary heart disease, and helping with weight maintenance. According to the 2010 Dietary Guidelines for Americans, we should aim to eat at least half of our grains as whole grains.
Source: U.S. Department of Agriculture