The whole grain guide.

Whole grains. Eat them more often, say experts.

"We know the whole grains are better than refined grains because of fiber, vitamins, and minerals," says researcher Joanne Slavin of the University of Minnesota.

Now she and others are beginning to ask whether other things in whole grains--antioxidants, lignans, phenolic acids, phytoestrogens, and other phytochemicals--may help reduce the risk of heart disease, cancer, and diabetes.

"Like fruits and vegetables, it's the package of nutrients that may be important," says Slavin.

Just last month, Harvard researchers reported that women who ate more whole grains had a lower risk of diabetes. Why?

"When you eat whole grains, you get more fiber and more micronutrients like folic acid, magnesium, and vitamin E," says Walter Willett, who chairs the nutrition department at the Harvard School of Public Health. "It may be almost impossible to isolate the pieces of the puzzle."

If whole grains are so healthy, why do an estimated 80 percent of us eat them less than once a day? It doesn't help that many people don't even know what whole grains are.