人们已普遍注意到妇女怀孕期叶酸的缺乏可导致婴儿神经管发育不全。但新近发现膳食中的叶酸不足可能与结肠、宫颈、肺及脑部癌症的发生有关。这个发现最早来自流行病学证据与动物研究，现已得到一项报告的支持：叶酸缺乏的分子机理能促进致癌作用。在该研究中，给予大鼠缺乏叶 It has generally been noted that the lack of folic acid in women during pregnancy can lead to the development of an infant with neural tube defects. However, it has recently been found that insufficient folate in the diet may be related to the occurrence of cancers of the colon, cervix, lung and brain. The discovery, first from epidemiological evidence and animal studies, is now supported by a report that the molecular mechanism of folic acid deficiency can promote carcinogenesis. In this study, rats were given leaves lacking