Grains provide many nutrients that are vital for the health and maintenance of your body. But not all grains and grain products are equally nutritious. Whole grains and grain products contain all of the parts of the grain — including the germ, the bran, and the endosperm — and are rich in fiber, vitamins, minerals, antioxidants, and phytochemicals (chemicals or nutrients derived from a plant source). Refined grains, such as white flour and white rice, are stripped of the bran and germ parts of the grain, which reduces the amount of fiber, antioxidants, and other nutrients in the grain.
The amount of grains you need for good health depends on your age, sex, and level of physical activity. While most Americans consume enough total grains on a daily basis, most of those grain servings are refined grains, and very few are whole grains. The Center for Nutrition Policy and Promotion, an organization of the U.S. Department of Agriculture established in 1994 to improve the nutrition and well-being of Americans, recommends making at least half of your grain choices whole. For most adults, that means consuming at least three servings of a cooked whole grain or whole grain bread, cereal, crackers, or pasta every day. In general, a serving of whole grains is about ½ cup of cooked cereal or grain, 1 slice of whole-grain bread, or 1 cup of whole-grain cold breakfast cereal. (For more on serving sizes, see “What Counts as an Ounce?”)
Whole grains naturally provide a number of nutrients, including dietary fiber, several B vitamins (thiamine, riboflavin, niacin, and folate), and minerals (iron, magnesium, and selenium). Refined grain products are often enriched with B vitamins and iron after processing, but they tend to provide significantly less fiber than whole grains.
Whole grains that contain soluble fiber, such as oats and barley, can help lower blood cholesterol levels when eaten in adequate amounts. They may therefore prevent plaque buildup in the arteries, and may lower the risk of heart disease.
Insoluble fiber, which is found in large amounts in whole wheat products, can help prevent constipation and diverticulosis, a condition in which there are small pouches in the colon that bulge outward. While diverticulosis itself may cause no symptoms, if the pouches become infected or inflamed, a condition called diverticulitis, a person will feel pain, and medical intervention is necessary. Diverticulosis is thought to be caused by increased pressure within the colon, which is often a result of chronic constipation.
Fiber-containing foods such as whole grains also help provide a feeling of fullness when eating, perhaps leading to a decrease in calorie intake.
The B vitamins play a key role in metabolism: They help the body use the energy it gets from protein, fat, and carbohydrate. B vitamins are also essential for a healthy nervous system. Many refined grains are enriched with thiamine, riboflavin, niacin, and folic acid, the synthetic form of folate that is found in supplements and added to foods. In fact, in the United States, manufacturers of enriched breads, flours, corn meals, pastas, rice, and other grain products have been required to add folic acid to their products since 1998.
Folate helps the body form red blood cells. Women of childbearing age who may become pregnant and those in the first trimester of pregnancy are advised to consume adequate folate to reduce their chances of having a baby with a type of birth defect known as a neural tube defect, which includes spina bifida and anencephaly. For many women, consuming folic acid in fortified foods or supplements—in addition to consuming folate-rich foods—is necessary to get enough.