Folic Acid

Folic acid is widespread in the food supply, with the highest concentrations in liver, yeast, leafy vegetables, fruits, and legumes. It is now also fortified in grain products (breads, cereals, spaghetti) within the United States, where fortified foods deliver approximately 140 micrograms of folate per 100 grams of food. It is easily destroyed through common household food preparation techniques and long storage times, so it is often most highly concentrated in fresh foods. Folate functions in amino acid metabolism and nucleic acid synthesis (RNA and DNA), and a deficiency leads to alterations in protein synthesis.Tissues with a rapid turnover are particularly sensitive to folic acid, including red and white blood cells as well as tissues of the gastrointestinal tract and the uterus. Adequate folate intake immediately before and during pregnancy is associated with the elimination of fetal neural tube defects (most notably spina bifida).^{29, 30}

Folic acid is measured in dietary folate equivalents (DFE), where 1 DFE equals

• 1 microgram of food folate;
• .6 micrograms of folate from fortified food or as a supplement consumed with food; or
• .5 micrograms of a folate supplement consumed on an empty stomach.

Because folate functions with vitamin B₁₂ in forming healthy new red blood cells, a deficiency leads to megaloblastic anemia. Other deficiency problems include gastrointestinal distress (diarrhea, malabsorption, pain) and a swollen, red tongue. Folate toxicity from excess intake has not been reported in humans, and no studies have reported on the relationship between folic acid and athletic performance. However, since athletes have an above-normal tissue turnover because of the pounding the body takes in various sports, and with the evidence that red blood cell turnover is faster in athletes than in nonathletes^{31, 32} there is good reason for athletes to be certain that adequate folic acid intake is satisfied. The best approach is through the regular consumption of fresh fruits and vegetables. If this is not possible, a daily supplement at the level of the DRI (400 micrograms per day) is an effective means of maintaining folate status.