What is folic acid used for?

Vitamin B9, also known as folic acid or folate, is used to treat kidney disease, to decrease the side effects of the medication methotrexate and to reduce the risks of birth defects, states WebMD. It may also be used to treat vision loss, depression, high blood pressure and gum disease.

Folic acid reduces high levels of homocysteine by up to 30 percent, which is a problem in about 85 percent of people with kidney disease, according to WebMD. By taking 400 milligrams of folic acid each day during early pregnancy, pregnant woman reduce the chances of brain and spinal cord defects in the developing fetus.