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. Simple carbohydrates, sometimes called
simple sugars, include fructose (fruit sugar), sucrose (table sugar), and lactose (milk
sugar), as well as several other sugars. Fruits are one of the richest natural sources of
simple carbohydrates. Complex 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. The glucose is then either used directly to
provide energy for the body, or stored in the liver for future use. When a person consumes
more calories than the body is using, a portion of the carbohydrates consumed may also be
stored in the body as fat.
When choosing carbohydrate-rich foods for your diet, always
select unrefined foods such as fruits, vegetables, peas, beans, and whole-grain products,
as opposed to refined, processed foods such as soft drinks, desserts, candy, and sugar.
Refined foods offer few, if any, of the vitamins and minerals that are important to your
health. In addition, if eaten in excess, especially over a period of many years, the large
amounts of simple carbohydrates found in refined foods can lead to a number of disorders,
including diabetes and hypoglycemia (low blood sugar). Yet another problem is that foods
high in refined simple sugars often are also high in fats, which should be limited in a
healthy diet. This is why such foods-which include most cookies and cakes, as well as many
snack foods-are usually loaded with calories.
Dietary fiber is the part of a plant that is resistant to
the body's digestive enzymes. Only a relatively small amount of fiber is digested or
metabolized in the stomach or intestines. Most of it moves through the gastrointestinal
tract and ends up in the stool.
Although most fiber is not digested, it delivers several
important health benefits. First, fiber retains water, resulting in softer and bulkier
stools that prevent constipation and hemorrhoids. A high-fiber diet also reduces the risk
of colon cancer, perhaps by speeding the rate at which stool passes through the intestine
and by keeping the digestive tract clean. In addition, fiber binds with certain substances
that would normally result in the production of cholesterol, and eliminates these
substances from the body. In this way, a high-fiber diet helps lower blood cholesterol
levels, reducing the risk of heart disease.
It is recommended that about 60 percent of your total daily
calories come from carbohydrates. If much of your diet consists of healthy complex
carbohydrates, you should easily fulfill the recommended daily minimum of 25 grams of
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