Health Supplement

Folic acid (also known as vitamin B9 or folacin) and folate (the naturally occurring form), as well as pteroyl-L-glutamic acid and pteroyl-L-glutamate, are forms of the water-soluble vitamin B9.
It is used in our bodies for cell formation and multiplication, DNA replication, formation of red and white blood cells, and other important central functions. You can take in natural folic acid from many foods such as green, leafy vegetables, fruits, beans, peas, peanuts, and meat sources.

A deficiency of folate can occur when an increased need for folate is not matched by an increased intake, when dietary folate intake does not meet recommended needs, and when folate loss increases. Medications that interfere with the metabolism of folate may also increase the need for this vitamin and risk of deficiency.

Folic acid supplementation is encouraged for those who are possibly folic acid deficient and those who have increased need of it, such as in the case of pregnant women.
Folic acid has also been used as medication for treating conditions such as megaloblastic anemia, depression, heart conditions, and so on. However, before deciding that you need to take folic acid supplements yourself to counter any of these conditions, it is always best that you see your doctor beforehand.

Tolerable Upper Intake Levels for Folate for Children and Adults

Intake of supplemental folic acid should not exceed 1,000 micrograms (?g) per day to prevent folic acid from triggering symptoms of vitamin B12 deficiency. Folic acid supplements can correct the anemia associated with vitamin B12 deficiency. Unfortunately, folic acid will not correct changes in the nervous system that result from vitamin B12 deficiency.

Source:
http://en.wikipedia.org/wiki/Folic_acid

http://www.nutritional-supplements-health-guide.com/side-effects-of-folic-acid.html