Is High Potency Folic Acid Safe?

Folic acid, also known as folate or folacin, is one of the B-complex vitamins. It is found in high concentrations in the foliage of dark green vegetables, such as spinach, chard and kale. Folate has gained attention for its role in preventing neural tube defects, a congenital malformation that interferes with the development of an infant's brain and spinal cord. To reduce the risks of neural tube defects, nutritionists recommend women take higher than normal doses of folate both before and during pregnancy.

Functions

Folic acid is required for the synthesis of DNA and RNA and the metabolism of amino acids and proteins. Your requirement for folic acid increases during times of growth or rapid cellular division, such as pregnancy. Folic acid -- in cooperation with vitamin B-12 -- is instrumental in the synthesis of hemoglobin, which is the oxygen-carrying protein in your red blood cells. Folate helps to maintain the balance of neurotransmitters, such as serotonin, epinephrine and norepinephrine, in your brain and central nervous system.

Toxicity

According Dr. Elson Haas, author of "Staying Healthy with Nutrition," there are no specific symptoms attributable to high doses of folic acid, although daily doses of 2 to 5 mg can sometimes cause insomnia, irritability and intestinal upset. Ostensibly, these symptoms prompted the National Academy of Sciences to set a tolerable upper limit of 1 mg for adults. However, the interaction between folic acid and vitamin B-12 could be a more compelling reason for establishing an upper limit for folic acid.

Interaction with B-12

In conjunction with vitamin B-12, folic acid helps to form normal red blood cells. A deficiency of either B-12 or folic acid leads to a condition called megaloblastic anemia, which is characterized by abnormally large, poorly functioning red blood cells. Unlike folic acid, vitamin B-12 is also essential for maintaining myelin, a material that protects your nerve cells. The anemia caused by vitamin B-12 deficiency can be corrected by taking additional folic acid, but folic acid cannot rebuild myelin damaged due to a lack of B-12. Therefore, the consumption of high-potency folic acid in the face of vitamin B-12 deficiency could "mask" the latter and allow progressive and irreversible nerve damage to occur.

Recommendations

Folic acid is essential for the production of normal red blood cells and other rapidly dividing cells, and it serves a vital role in preventing neural tube defects. Its ability to mask vitamin B-12 deficiency has prompted regulatory agencies to set a tolerable upper limit of 1 mg for adults. Recommended daily intakes range from 65 mcg for infants to 600 mcg for pregnant women. The National Academy of Sciences recommends that all women who are capable of becoming pregnant take 400 mcg of folic acid daily.