Folic acid, a water-soluble
vitamin, has been used since the 1940s to treat some cases of
macrocytic anemia without neurologic disease.
Folate deficiency is best diagnosed with red blood cell
folate levels along with macrocytosis and/or
megaloblastic anemia. In addition to reversing overt deficiency, the
vitamin may reduce the incidence of
neural tube defects by 45% in women who receive 400 micrograms per day. It is recommended that all women of childbearing age take 400 micrograms of
folate per day. Elevations in
homocysteine levels, a metabolite intimately associated with
folate, are also being found with increasing regularity in those with
cardiovascular diseases.
Homocysteine levels are reduced by
folic acid administration. Therefore, there is some biologic plausibility, but not currently direct proof, for the assumption that
folate supplements may prevent
heart disease,
stroke, and
peripheral arterial disease. Controlled trials should take place before widespread food supplementation with
folate is carried out on a large scale because of the possibility of outbreaks of permanent B12-related neurologic damage in those with undiagnosed
pernicious anemia. However, if a patient has a premature cardiovascular event and has minimal risk factors, ordering a test to determine
homocysteine level may be advisable, and if elevated, treating with
folic acid supplement as long as B12 deficiency does not coexist.