Vitamins are substances needed in very small quantities. They are involved in numerous metabolic reactions and must be consumed in the diet. Vitamins are water - soluble or fat - soluble. Water - soluble vitamins, such as vitamin C, tend to act as coenzymes (work with enzymes lo cause a chemical reaction). They are stored in small quantities, so regular intake is essential. Fat - soluble vitamins do not act as coenzymes and are stored in greater quantity than water - soluble vitamins. With a few exceptions, active people do not benefit from vitamin supplements. The best dietary strategy for adequate vitamin intake continues to be selecting a balanced diet from the basic food groups.
A variety of vitamins has been used as ergogenic aids. These substances, although essential, are required in extremely small quantities. Because mitochondria increase due to endurance training, more vitamins may be needed to support the increased metabolic activity. However, vitamin deficiency in athletes has not been consistently demonstrated. In fact, most athletes take many times the minimum daily requirement for these substances. Only levels of vitamin C, thiamin, pyridoxine, and riboflavin decrease with exercise (due to increased metabolism). These vitamins are not lost in sweat.
