Complex carbohydrates are composed of sugar molecules strung together in long chains and branches. They are found in a variety of foods, including grains, vegetables and legumes. Most complex carbohydrates are either starches or fiber and contain links of at least three sugars. The Dietary Guidelines for Americans 2010 recommends that most healthy people consume between 45 and 65 percent of their calories as carbohydrates, with most of these coming from complex carbohydrates.
Grains
Rice, barley, bulgur, whole wheat bread, couscous, pasta, cereal and corn are examples of grains that are complex carbohydrates. Plants from which these foods come generate glucose through photosynthesis, and they can densely pack tens of thousands of sugar molecules in tiny grains. Plants store the glucose as starch, which they use much like the stored glycogen in humans as a reserve energy source. When you eat these plants, you acquire the rich stores of complex carbohydrate provided that food processing has not stripped them away. This is part of the reason behind the advice that you buy whole grain breads, pastas and cereals.
Legumes
Starchy legumes like beans, peas and lentils are also complex carbohydrates. Legumes are simply plants with seeds that develop inside pods. Garbanzos and edamame are other examples. One reason public health authorities want you to eat more complex carbohydrates such as beans is that they tend to digest more slowly than processed and simple carbohydrates. They help with blood sugar control, regularity and weight control. Many legumes have the added benefit that they are good sources of protein.
Vegetables and Tubers
Potatoes, sweet potatoes, spinach, artichoke, zucchini, Brussels sprouts and broccoli are among the leafy and cruciferous vegetables and root tubers classified as complex carbohydrates. The Dietary Guidelines for Americans 2010 encourages people to increase their vegetable intake. Not only do vegetables provide important vitamins and minerals; there's also evidence they protect against weight gain. Adult men and women need between 2 and 3 cups of vegetables daily.
Fiber
Fiber is a special type of complex carbohydrate. It is part of the structural component of plants and not a nutrient. Its composition is such that your digestive enzymes can't break it down, so it passes through undigested and without providing many calories. However, fiber may help lower cholesterol, regulate your blood sugar, control your appetite and prevent constipation. In the body, some fibers pass through slowly while others swell up like a sponge, forming a gel that provides many health benefits. Fiber often tags along with other complex carbohydrates. You'll find fiber in oat bran, barley, nuts, seeds and wheat bran.
Fruits
A select few fruits count as complex carbohydrates, including blueberries, bananas and cantaloupe. Although many fruits are abundant sources of simple sugars, some are quite fibrous and so qualify as complex carbohydrates. According to the U.S. Department of Agriculture's new MyPlate -- the scheme that replaced the food pyramid -- most American adults need to consume between 1.5 and 2 cups of fruit daily.
References
- Harvard School of Public Health: Carbohydrates: Good Carbs Guide the Way
- University of Illinois at Urbana-Champaign College of Agricultural, Consumer and Environmental Sciences: What Are Complex Carbohydrates and Fiber?
- "Diabetes Forecast"; The Science of Carbs; Erika Gebel; September 2009
- USDA: Dietary Guidelines for Americans, 2010
- ChooseMyPlate.gov: How Much Fruit Is Needed Daily?
- ChooseMyPlate.gov: How Many Vegetables Are Needed Daily or Weekly?
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