Folic Acid

Folic acid, whose chemical name is pteroylmonoglutamic acid, was first isolated in 1945. Folic acid is B vitamin found in leafy greens, animal proteins, fruits, and vegetables. Humans absorb this vitamin from the proximal small intestine and store folate primarily in the liver and red blood cells (RBCs). Folate is indirectly responsible for the synthesis of DNA. Many etiologies exist for folate deficiency including infection, pregnancy, malabsorption/starvation syndromes, certain cancer medications, and antibiotics. With low levels of folic acid, RBCs tend to enlarge in volume, a term known as macrocytosis. With this enlargement, RBCs are not able to routinely carry enough oxygen to tissues creating a scenario known as megaloblastic anemia. Megaloblastic anemia can be diagnosed by measuring the mean volume of RBCs, examining peripheral blood smears of RBCs, measuring serum folate levels, and by examining bone marrow.

Another major cause of megaloblastic anemia is vitamin B12 deficiency. The distinction between the two disease states is important in terms of treatment. If the cause of the anemia is due to vitamin B12 deficiency, increasing the dietary folate levels may improve the anemia temporarily but will not prevent the neurologic decline that occurs with vitamin B12 deficiency. Similarly, in the case of malabsorption syndromes, increasing the folate intake will not improve the ultimate source of the vitamin loss.

Among the general public, folic acid is most well known for its importance in preventing neural tube defects (NTDs). The incidence of these ailments affecting proper development of the brain and spinal cord are significantly reduced by as much as 70 percent with the minimum daily dietary intake of 400 ¼g. The mechanism by which folate is able to prevent NTDs is not completely understood and the involvement in NTD development is possible even in the first week of pregnancy when a woman may be unaware she is pregnant. Thus, all women of childbearing age are especially encouraged to incorporate folic acid into their diets.

In the United States, most flour and grain products are supplemented with folic acid in order to decrease the number of infants born with NTDs; however, supplementation in European or Australian countries is not required and has become a topic of controversy. Pregnant women are encouraged to maximize their dietary intake of folic acid; however, more than 1,000 ¼g daily affords no additional benefits and any adverse effects at this dosage have not yet been elucidated. The U. S. Department of Health and Human Services encourages dietary intake of folic acid through fortified dry cereals, supplements, or by eating fruits and vegetables high in folic acid. Folic acid is being examined in the cardiovascular arena with studies showing a promise of improved heart health, a decreased incidence of stroke, and a decrease in congenital heart defects.