The second category of carbohydrates is the starches, or polysaccharides. These are also termed the complex carbohydrates, as they are composed of long chains of glucose molecules. Starches require amylase enzymes (other biochemical catalysts) to be broken down into simple sugars for digestion, absorption, and utilization.
Starch provides a more consistent blood sugar level than the simple sugars, which cause the glucose level in the blood to rise and fall rapidly. In the traditional diet, a high percentage of foods consumed included the complex carbohydrates of potatoes, vegetable roots, and whole grains such as wheat, rice, and corn. This was much healthier than the present-day preference for high-sugar and refined-flour diets, which are associated with degenerative tissue disease and aging.
There are several types of starches. If the polysaccharide chains are shorter and branched, the starch is called amylopectin—the most common one found in foods. Amylose has long chains of glucose molecules, which are easily separated by the enzyme amylase. Glycogen is the animal-source starch contained in muscle and liver. It is similar in structure to amylopectin and can be broken down to release glucose for energy needs or be formed from extra glucose and stored in the liver. Glycogen is really the form in which glucose is stored in our body. Dextrins are partially digested starches that are formed in the breakdown of starch.
The third component of carbohydrates is fiber—mainly the indigestible cellulose commonly found in the skins of fruits and vegetables and in the coverings of cereal grains, such as wheat bran. This fiber in foods provides little energy or caloric value. As mentioned earlier, it fosters good intestinal function and elimination. Low-fiber diets are associated with constipation, gastrointestinal disorders, diverticulosis, and colon cancer, while a high-fiber diet may prevent these problems. Fiber in the diet may also reduce the risk of appendicitis.
Cellulose is the most common fiber contained in basic foods. Other fibers include the hemicelluloses, found in the cell walls of plants, which have a high ability to bind water. This helps in digestion and elimination. Psyllium seed husks are a good example of a hemicellulose. They are a popular fiber supplement used to provide bulk and to speed transit time through the bowels. Pectin is another hemicellulose, which, besides absorbing water, can lower the amount of fat absorption. This is the pectin found in the rind of citrus fruits and in the pulp of apples, which is also used in making jams.
Other fibers used in the diet include both agar and alginate (derived from seaweed) and carrageen, which comes from the Irish moss plant. All indigestible polysaccharides, they are used in food preparation and in cosmetics for their smooth gelatinous consistency. Carrageen is used commonly with dairy products such as yogurt to create a smooth consistency.
Agar is used to bring a gelatinous quality to foods and desserts. Alginate can bind up minerals and metals, such as cadmium, mercury, lead, and arsenic, in the intestines and has been found useful in detoxification programs.
Several other high-fiber substances that have some use in the diet have been shown in preliminary research to help reduce cholesterol levels because of their ability to hinder fat absorption from the intestines. Guar gum may also be used to slow glucose uptake in the intestines and may be helpful in mild diabetes. Konjar root flour from Japan has also been shown in tests to have some influence in moderating diabetes, in lowering cholesterol levels, and in weight control.