Numerous observational studies have linked a diet rich in whole grains to a reduced risk of heart disease. For example, a six-year study of more than 40,000 male health professionals (ages 40 to 75) found that men with the highest fiber intake -- especially from cereal and other grains -- were 40% less likely to have a heart attack than those with the lowest fiber intake. A more recent study that followed more than 27,000 postmenopausal women for 17 years reported that those who ate the most whole grains (19 or more servings per week) were nearly 30% less likely to die of heart disease than those who ate the least.
There is also some evidence that whole grains other than oats may have a beneficial effect on heart health. For instance, in a study published in the American Journal of Clinical Nutrition, 50 obese adults with the metabolic syndrome were randomly assigned to a low calorie diet that was rich in either whole grains or refined grains. Three months later, people in both groups lost weight (about 10 lbs, on average). However, those who ate a larger amount of whole grains lost more abdominal fat than those who ate more refined grains. In addition, people in the whole-grain group saw their levels of CRP drop by 38%; CRP levels remained unchanged in the refined-grain group.
Based on studies like these, the U.S. Food and Drug Administration allows foods that contain more than 50% whole grains by weight to state on the label that "diets rich in whole-grain foods… and low in total fat, saturated fat, and cholesterol may reduce the risk of heart disease…"
What's So Special About Whole Grains? Whole grains contain the whole kernel -- the endosperm and germ inside a coating of bran. The germ is packed with vitamins, minerals, and antioxidants, while the bran is fiber rich. During the manufacturing of refined grains (such as white flour), the germ and bran are removed, leaving only the starchy endosperm. With refined grains, manufacturers do add back some of the lost nutrients -- notably, the B vitamins and iron -- but not the fiber and other healthful vitamins and minerals.
What nutrients in whole grains might help reduce the risk of heart disease? First, there is the soluble fiber, which helps lower LDL cholesterol, and the insoluble fiber, which prolongs satiety (helpful for people trying to lose weight). Then there are the minerals like potassium and magnesium that are important for blood pressure control. Last, antioxidants, such as vitamin E, in the germ may help quell inflammation that can spur atherosclerosis.
Bottom line: The latest dietary guidelines recommend eating a minimum of three servings of whole grains every day. One serving is equal to one slice of whole-grain bread, ½ cup of whole-grain cereal, or ½ cup brown rice or whole-wheat pasta.
Whole grains include whole wheat, oats, brown rice, wild rice, hulled and dehulled barley, buckwheat, bulgur, popcorn, millet, amaranth, spelt, kamut, and quinoa. When choosing whole-grain products, look for the words "100% whole wheat" or "100% whole grains."
