Folic acid is the synthetic form of vitamin B9, found in supplements and fortified foods. It holds up better than natural food folate and the body absorbs it well. Once inside, the body must convert it to methylfolate, the active form it can actually use. Some people with MTHFR gene variants make this conversion less efficiently, which is why active folate forms exist as an alternative.
Cell growth and division depend on this vitamin. That demand spikes during fast growth periods like pregnancy and infancy. Women who are planning a pregnancy or in the early stages often take it to support fetal development. It also helps maintain normal red blood cell production and can address low folate levels caused by poor diet, absorption trouble, or certain medications.
Most people take it daily as part of a B-complex or on its own. High doses can hide a vitamin B12 deficiency, a real risk for older adults or anyone with pernicious anemia. Folic acid can also interact with some anticonvulsant drugs, so get medical advice before starting if that applies to you.