Quick Q&A on Carbs

Arlington, VA, January 3, 2007 — What are carbohydrates? Carbohydrates are the body’s major energy source, providing four calories per gram. They are classified by their chemical structure. Monosaccharides are single unit carbohydrates, disaccharides are two monosaccharides linked together, and polysaccharides are carbohydrates with multiple single-unit sugar molecules linked together to form one long-chain carbohydrate. They are generally referred to as either simple, meaning one or two unit molecules or complex, meaning the long-chain polymers. Although there are some exceptions, simple carbohydrates are usually sugars or sweeteners like sugar or honey and complex carbohydrates are starches like rice or oatmeal. A healthful diet would be composed of a variety of carbohydrates, but primarily of those from fruits and vegetables, rice, breads, cereals and other grains and nonfat or lowfat dairy products.

Why are carbohydrates important? Carbohydrates are the key energy-supplying nutrient for the body. Without adequate carbohydrates, the body cannot supply the muscles, brain and virtually every living cell with the energy it needs. In fact, the brain and nervous system utilize solely carbohydrates for their energy source.

How many carbohydrates do we need? The Institute of Medicine (IOM) recommends a Dietary Allowance (RDA) for carbohydrate of 130 grams per day to avoid any negative effects from too little carbohydrate in the diet. A half-cup of cooked rice has 22 grams of carbohydrates.

What percentage of daily calories should come from Carbohydrates? The IOM recommends that adults get 45 percent to 65 percent of their calories from carbohydrates, 20 percent to 35 percent from fat, and 10 to 35 percent from protein. Acceptable ranges for children are similar to those for adults, except that infants and younger children need a slightly higher proportion of fat (25 %-40%).