Eating a bowl of oatmeal for breakfast has long been touted as one of the healthiest ways to start the day. That's because oats contain soluble fiber that's been shown to help lower blood cholesterol. But two studies show that fiber may be only part of the health benefits contained in this common grain.

Until recently, scientists believed that it was the beta-glucan contained in the soluble fiber found in oats that was responsible for their cholesterol-lowering effect. While beta-glucan plays a part in this process, it's not the whole story.

Chemicals that are good for you

Like fruits and vegetable, oats also contain phytochemicals, which are naturally occurring chemicals in plants that help fight disease. Oats, in particular, have lots of flavonoids. These are powerful antioxidants that help prevent heart disease and cancer. Nearly 4,000 flavonoids have been identified in the plant world, but researchers only have recently begun to explore how the ones found in oats can be beneficial.

To study their benefits, researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University extracted some of the phytochemicals found in oats to see their effects on cholesterol and other substances found in the bloodstream.

In one study, scientists took LDL (bad) cholesterol and added flavonoids extracted from oats. They found the oat extract inhibited the oxidation of LDL, which contributes to the formation of plaque in the arteries of the heart. What's more, they found that adding small amounts of Vitamins C and E - potent antioxidants on their own - had a much larger effect than predicted.

What we appear to be doing is building a story that says that it's more than soluble fiber, explains researcher Jeffrey Blumberg, Ph.D., professor of nutrition and chief of the antioxidants research laboratory at Tufts University. Mother Nature provided more of these [flavonoids] than just those found in fruits and vegetables.

In another study, researchers studied the effect of flavonoids called avenanthramides on human aorta cells and found that these chemicals reduced the number of molecules that adhere to the cells. This suggests that avenanthramides may help reduce the plaque that sticks to artery walls and reduces blood flow in the heart. They also appeared to have an anti-inflammatory effect by reducing the production of cytokines, proteins that play a role in the body's immune response. Both studies were partly funded by the Quaker Oats Company.

While the studies have yet to be conducted in human subjects (Blumberg's team already has tested hamsters and will be using human volunteers next), the researchers believe they open an important door to understanding the role flavonoids have in maintaining good health.

The assumption is that the presence of these compounds in natural foods will prevent late life problems, says Mohsen Meydani, D.V.M., Ph.D., professor of nutrition and director of the vascular biology laboratory at Tufts University, who worked on the avenanthramides study.

The idea that grains such as oats can be as beneficial as fruits and vegetables and may even work in harmony with them has a lot of appeal. Remember, grains are at the base of the food guide pyramids, Blumberg points.

The American Heart Association recommends eating 25 grams to 30 grams of fiber from food each day. This includes both the soluble fiber found in oats, beans, peas, rice, strawberries and apples and the insoluble fiber found in most other grains, cabbage, beets and cauliflower. Soluble fiber forms a gel when mixed with liquid, while insoluble fiber does not. Insoluble fiber passes through your digestive tract largely intact.

Adding oats to your diet

If you're wondering how to add oats to your diet besides eating oatmeal, try substituting oats for up to one-third of the flour in breads, cookies, cakes and muffins, adding oats to meat-based recipes such as meatloaf or meatballs, or using oats as breading for fish and chicken.

If you do increase the amount of oats you eat, remember that it's just one part of a healthy diet. The flavonoids that we get from oats may complement the flavonoids we get from other foods, Blumberg says.