"That one is the biggest change," says NPD Group vice president Harry Balzer, comparing the 2005 guidelines with the preceding ones. "About 10 percent of the total grains we eat are whole grains, most probably as ingredients in some cereals and breads," says Balzer, who for 26 years has tracked American diet trends and eating patterns for the Long Island, N.Y.-based global marketing information company.

The suggested amount of whole grains is three or more one-ounce equivalents per day. Most Americans don't come near that. Instead, we regularly consume the refined grains commonly found in cereals, cookies, pastries, breads, white rice, pasta, even frozen dinners.

As defined by the Whole Grains Council, a consortium of industry participants, scientists, chefs and the Oldways Preservation Trust, a food-issues think tank in Boston, whole grains or foods made from them contain all the essential parts and naturally occurring nutrients of the entire grain seed. If the grain has been processed (e.g., cracked, crushed, rolled, extruded, lightly pearled and/or cooked), the food product should deliver approximately the same richness of nutrients found in the original grain seed.

The dietary guidelines booklet suggests whole-grain cereals, breads, crackers, rice or pasta as possible sources. Beyond that, however, most of us aren't familiar with the range of whole grains available.

The whole grains the scientists working on the dietary guidelines found somewhere in the American diet (as a single food, such as wild rice, or as one of multiple ingredients, such as in bread) are, in decreasing order of U.S. consumption: whole wheat, whole oats/oatmeal, whole-grain corn, popcorn, brown rice, whole rye, whole-grain barley, wild rice, buckwheat, triticale (a wheat-rye hybrid), bulgur (cracked wheat), millet, quinoa and sorghum.

Increasingly, these grains, and more exotic ones, are available singly or as ingredients in foods found in health or natural-food stores and in larger outlets such as the Whole Foods chain. Some food manufacturers have agreed to use whole-grain stamps (developed by the Whole Grains Council) on their packaging. One of those companies, General Mills, has already announced the inclusion of whole grains in all its cereals.

Until those stamps become commonplace, consumers should look at ingredient lists to assess the presence and amounts of whole grains in commercial food products. The words to look for, especially as the first ingredient, are whole grains, whole wheat (or other grains), or stone-ground whole grains. In addition, whole-grain cereals or breads should deliver at least 3 grams of fiber per serving.

Will Americans rise to the challenge? "First we have to have products out there to try," says Balzer.