The Four Basic Nutrients Carbohydrates Carbohydrates supply the body with the energy it needs to function. They are found almost exclusively in plant foods, such as fruits, vegetables, peas, and beans. Milk and milk products are the only foods derived from animals that contain a significant amount of carbohydrates. Carbohydrates are divided into two groups-simple carbohydrates and complex carbohydrates.
Fruits are one of the richest natural sources of simple carbohydrates.
Com plex carbohydrates are also made up of sugars, but the sugar molecules are strung together to form longer, more complex chains. Complex carbohydrates include fiber and starches. Foods rich in complex carbohydrates include vegetables, whole grains, peas, and beans. Carbohydrates are the main source of blood glucose, which is a major fuel for all of the body's cells and the only source of energy for the brain and red blood cells. Except for fiber, which cannot be digested, both simple and complex carbohydrates are converted into glucose.