Swain R A, St Clair L
Department of Family and Sports Medicine, West Virginia University-Charleston Division 25301, USA.
J Fam Pract. 1997 Feb;44(2):138-44.
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.
叶酸是一种水溶性维生素，自20世纪40年代以来一直用于治疗某些无神经系统疾病的巨幼细胞贫血病例。叶酸缺乏最好通过红细胞叶酸水平以及大细胞性贫血和/或巨幼细胞贫血来诊断。除了纠正明显的缺乏外，这种维生素还可以使每天摄入400微克的女性神经管缺陷的发生率降低45%。建议所有育龄妇女每天摄入400微克叶酸。同型半胱氨酸水平升高，这是一种与叶酸密切相关的代谢产物，在心血管疾病患者中也越来越常见。补充叶酸可降低同型半胱氨酸水平。因此，对于叶酸补充剂可能预防心脏病、中风和外周动脉疾病这一假设，有一定的生物学合理性，但目前尚无直接证据。由于未确诊的恶性贫血患者可能会爆发永久性的与维生素B12相关的神经损伤，因此在大规模广泛进行食物叶酸补充之前，应进行对照试验。然而，如果患者发生过早的心血管事件且危险因素极少，建议进行检测以确定同型半胱氨酸水平，如果水平升高，只要不存在维生素B12缺乏，就用叶酸补充剂进行治疗。
