Folic acid, also known as folate, is one of the B-complex vitamins. Like other B vitamins, folate is water-soluble, so dietary excesses are readily eliminated in your urine. However, unlike many B vitamins, enough folate is stored in your liver to last six to nine months, according to nutritionist Elson Haas. Most of the folic acid in your body is present in an inactive form called methyl folate. Vitamin B-12 is required to convert it to its active form, called tetrahydrofolic acid. THFA is instrumental in producing normal red blood cells.
Functions
Folic acid functions as a cofactor for enzymes that perform a single task in your cells: The transfer of single-carbon units to more complex molecules. This activity is particularly important in the manufacture of hemoglobin, which is the oxygen-carrying pigment in your red blood cells, and for the synthesis of DNA, which is required for the production of any new cell. Whenever THFA participates in a carbon-transfer operation, it is "deactivated" to its methyl folate form. Vitamin B-12 is needed to recycle THFA.
Anemia
The word anemia means "without blood." Anemia occurs when you have fewer red blood cells than normal or when the amount of hemoglobin in your red blood cells is decreased. "The Merck Manual of Diagnosis and Therapy" states that anemia occurs in three settings: inadequate production of red blood cells, loss of red cells due to bleeding and excessive destruction of red blood cells. A lack of activated folic acid interferes with red blood cell production and leads to a condition called megaloblastic anemia, which is characterized by abnormally large, poorly functioning red blood cells.
Masking
Vitamin B-12 cooperates with folic acid in the synthesis of hemoglobin and the production of red blood cells. A B-12 deficiency can cause a megaloblastic anemia that is indistinguishable from the anemia caused by folic acid deficiency. Taking extra folic acid can lead to a resolution of the anemia caused by a vitamin B-12 deficiency, but vitamin B-12 performs another vital function -- keeping your nervous system healthy -- which cannot be corrected by taking additional folic acid. So, folic acid supplementation can "mask" a B-12 deficiency by correcting the anemia but allowing nerve damage to progress.
Recommendation
Whenever megaloblastic anemia is detected on a blood test, a B-12 levels should be checked to rule out deficiency of this vital nutrient. Blood levels of folic acid and other compounds -- homocysteine and methylmalonic acid -- can help pinpoint the cause of your anemia. If folic acid is determined to be the cause, it is prudent to take vitamin B-12 along with folic acid to ensure your nervous system is protected. Daily dietary recommendations for folic acid range from 65 mcg for infants to 600 mcg for pregnant women. B-12 requirements vary from 0.4 mcg for infants to 2.8 mcg for lactating women.
References
- "Staying Healthy with Nutrition: Folic Acid (Folacin or Folate)"; Elson M. Haas, M.D.; 2006
- Linus Pauling Institute; Folic Acid; Jane Higdon; April 2002
- "The Merck Manual of Diagnosis and Therapy, 18th Edition: Anemia"; Mark H. Beers, M.D., Editor-in-Chief; 2006
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