Folate protects a human fetus from neural tube defects (NTDs). Two types of NTDs include anencephaly and spina bifida. This is the only instance in which a congenital malformation can be prevented, simply. If the neural tube does not close during development of the embryo, congenital defects can result.
Folate is a B-complex vitamin that is a coenzyme for nucleic acids and amino acids. It is necessary for purine and pyramidine metabolism, and important for growth and reproduction. Folic acid is the most active form and is rarely found in food. The form found in food is folate and, “Food folate is only about half as available for use by the body as folic acid.” Cereal grains have been mandated to be supplemented with folic acid by the U.S. government since January first, 1998.
The current advice is that all women who are capable of childbearing are urged to take folic acid on a regular basis. The current dose recommended is .4 mg./day (400 mcg./day) for all women and 4.0 mg./day for women who have had a previous NTD pregnancy. Supplementation must be started early because the closure of the neural tube occurs quite early. Ideally folic acid therapy should start before pregnancy.
The folic acid fortification in the United States may have resulted in a 25-30% reduction of NTDs. Further research is needed to explore the best dose needed to prevent NTDs. (One reason that neural tube defects have declined over the past thirty years is improved prenatal diagnosis and therapeutic abortions.)
CONCLUSION: Treatment with folic acid before pregnancy or very early in pregnancy has been shown to reduce neural tube congenital defect incidence. The optimum dosage has not yet been determined.
NOTE: Spina bifida is the failure of normal development of the lower bony covering over the spinal cord. Anencephaly is a failure of the normal development of the brain, usually resulting in death soon after birth.
Neural tube closure occurs quite early in the development of the fetus, between two and 6 weeks of development. This happens before many women know they are pregnant. For this reason, all women of childbearing age should receive folic acid for adequate prevention of NTDs.
The following foods are said to be high in folic acid: Leafy, dark green vegetables, legumes (beans and peas), citrus fruits and juices and most berries. Read about the importance of folate in multiple sclerosis.
Pernicious anemia is a disease in which vitamin B-12 is low, resulting in an anemia made up of quite large red blood cells which are large, but deficient in number (megaloblastic anemia). Eventually, signs of central nervous system degeneration develop without B-12 treatment. The disease can be treated with B-12.
Folic acid will relieve the anemia of pernicious anemia, but the central nervous system continues to deteriorate. Therefore, doses of 1 mg. folic acid are not advised, especially in the elderly, because it can delay the diagnosis and treatment of pernicious anemia.
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