Vitamins are not a source of energy and do not have caloric value. They do not contribute to body structure. They are, however, indispensable for regulating body function and for maintenance of optimal health.
Vitamins are divided into 2 classes, fat soluble and water soluble. Fat soluble vitamins include Vitamins A, D, E and K. Some essential water soluble vitamins are Vitamins B1, B2, Niacin, B6, Pantothenic Acid, Folacin, B12, Biotin, Choline, Inositol, and C. Fat soluble vitamins are stored in the body to a greater degree than water soluble vitamins. Most vitamins must be obtained from food, a few are formed within the body.
The only difference between natural and synthetic vitamins is the way they are made. Usually it is better to get vitamins from food because they are in combination with minerals and other nutrients needed by the body. Synthetic vitamins may be indicated when deficiencies are noted. Most nutritionists feel that there is no evidence that the average American on a balanced diet suffers from vitamin deficiency. Little evidence exists to support the use of vitamin supplements by well nourished athletes or other highly active persons. However, Charles A. Garfield based on his research at the Performance Sciences Institute indicates that vitamin and mineral supplements can be important in the nutrition of competitors. He concludes that athletes can benefit from 2 multivitamin tablets with minerals per day. He also suggest extra amounts of Vitamin C (2,000-5,000 mg) and B Complex are advisable during strenuous training periods. His study of marathoners given the above vitamin supplements showed a drop in resting heart rates of 9 beats per minute while no significant changes were shown in a control group. Runners taking the supplements experienced 35% fewer injuries and 81% fewer infections than the control group. If you feel that you are not receiving a balanced diet for any reason, reasonable doses of vitamin supplements will not be harmful. However, excess quantities or megadoses can have undesirable side effects and are dangerous. A registered dietitian can answer more detailed questions regarding vitamin intake.