Carbohydrate is one of three major nutrients your body obtains from food. It's important as a source of glucose, which your digestive tract produces when it breaks down carbohydrate-containing foods. Glucose is a vital energy source that travels in your blood to reach all your cells. In addition to providing energy, whole-grain carbohydrates can have a positive effect on your body and are especially important for the health of your digestive system.
Seeds of wheat, oats, barley, rice and other similar plants used as food are commonly called grains, and foods that contain all parts of the grain are referred to as whole-grain foods. The outer cover of the grain, or bran, is a fibrous layer that protects the underlying endosperm, the seed's food supply, and the tiny, inner germ, which is the seed's embryo. Because bran is indigestible, it is often removed during processing, such as in production of white flour from wheat or white rice from brown rice. Carbohydrate-containing food that includes processed grains is quicker and easier to digest, but has fewer health benefits than whole-grain foods.
Whole-grain carbohydrates are generally rich in fiber and especially good sources of insoluble fiber, which is concentrated in the grain's bran. As its name suggests, insoluble fiber cannot dissolve in liquids. It passes through your digestive tract essentially unchanged. However, it helps move food through the tract more quickly and eventually becomes part of your stool, helping keep it soft and preventing constipation. Experts at Harvard School of Public Health report that a diet rich in insoluble fiber can also help prevent or improve symptoms of an intestinal disorder called diverticular disease, potentially lowering your risk of the disease by as much as 40 percent.
Whole grains also contain another type of fiber called soluble fiber, which dissolves in liquid. When you consume soluble fiber, it forms a gel when mixed with liquid in your stomach, slowing the digestive process. This can slow uptake of glucose and dietary fat from food, helping keep your blood glucose from rising quickly and your blood cholesterol low after a meal. These effects can reduce your risk of Type 2 diabetes and cardiovascular disease, respectively. According to the University of Maryland Medical Center, soluble fiber in whole-grain carbohydrates can also help improve digestive problems such as diarrhea by making stool firmer and slower to pass, and can help relieve symptoms of hemorrhoids and of ulcerative colitis, an inflammatory bowel disease.
Sources and Recommendations
The 2010 Dietary Guidelines for Americans recommends that women and men who consume 2,000 calories daily should take in 25 and 38 grams of fiber, respectively. Consuming foods that contain whole-grain carbohydrates is a good strategy to help you reach this goal. Good examples of these foods include brown rice, barley, bulgur, buckwheat, oats, whole-wheat pasta and cereals, oatmeal and oat bran and breads and baked goods containing whole grains. For example, 1/2 cup of barley contains 3 grams of fiber, with about 2/3 as insoluble fiber; 1/3 cup of dry oatmeal provides provides almost 3 grams of fiber, equally divided among soluble and insoluble, while one slice of whole-wheat bread provides 1.5 grams fiber, mostly insoluble.
- Centers for Disease Control and Prevention: Carbohydrates
- Harvard School of Public Health: Fiber: Start Roughing It!
- Harvard University Health System: Fiber Content of Foods in Common Portions
- University of Maryland Medical Center: Fiber
- Whole Grains Council: What Is a Whole Grain?
- Whole Grains Council: U.S. Dietary Guidelines and WG
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