Why has my doctor put me on folic acid, i'm not pregnant and don't intend to be.

Good question: Contrary to popular belief vitamin supplements by and large have not been proven beneficial except in select situations. In fact, supplements could be harmful. Folic acid supplements have been shown to prevent neural tube defects in pregnancy. A prescription medication called Methotrexate used for automine conditions (R.A.) require supplementation. Otherwise it's not necessary unless deficient.

Not sure, but: Another possible reason to be on folate (folic acid) is for treatment-resistant depression. The l-methylfolate (folic acid) form is especially useful in this regard, because it does not need to be converted into an active form by your body (it already is "active.") since you didn't supply any other info, though, all of us are guessing here. What about simply asking your doctor why s/he feels you need this?