美国研究人员7月5日在美国《胃肠病学》杂志上发表研究报告称，大量摄入叶酸可以降低患结肠癌的风险。
美国癌症学会的研究人员在1999年至2007年对近10万人展开了研究，其中一部分人有大量摄入叶酸的习惯。在这期间，1023人被诊断出患结肠癌。结果显示，在两年内人们摄入多少叶酸对罹患结肠癌的影响差别不大，但坚持大量摄入叶酸两年以上者，患结肠癌的风险明显降低。
研究报告的主要作者、美国癌症学会的维多利亚·史蒂文斯指出，不管是自然摄入叶酸，还是服用营养补充剂形式的叶酸，都具有预防结肠癌的功能。只要摄入的叶酸达到一定总量，即可降低罹患结肠癌的风险。
其他学者则认为这一发现尚存争议，因为目前至少已有一项研究表明，叶酸补充剂对结肠腺瘤的影响不明显，而结肠腺瘤是结肠癌的“前奏”。
作为一种水溶性维生素B，叶酸是细胞正常生长以及DNA（脱氧核糖核酸）合成和修复所需的重要营养成分，它普遍存在于某些自然食品中，但一些补充剂也可以提供叶酸。（生物谷Bioon.com）
生物谷推荐原文出处：
Gastroenterology doi:10.1053/j.gastro.2011.04.004
High Levels of Folate From Supplements and Fortification Are Not Associated With Increased Risk of Colorectal Cancer
Victoria L. StevensMarjorie L. McCullough, Juzhong Sun, Eric J. Jacobs, Peter T. Campbell, Susan M. Gapstur
Background & Aims Folate intake has been inversely associated with colorectal cancer risk in several prospective epidemiologic studies. However, no study fully assessed the influence of the high levels of folate that are frequently consumed in the United States as a result of mandatory folate fortification, which was fully implemented in 1998, and the recent increase in use of folate-containing supplements. There is evidence that consumption of high levels of folic acid, the form of folate used for fortification and in supplements, has different effects on biochemical pathways than natural folates and might promote carcinogenesis. Methods We investigated the association between folate intake and colorectal cancer among 43,512 men and 56,011 women in the Cancer Prevention Study II (CPS-II) Nutrition Cohort; 1023 were diagnosed with colorectal cancer between 1999 and 2007, a period entirely after folate fortification began. Cox proportional hazards regression was used to calculate multivariate hazards ratios (RR) and 95% confidence interval (CI).
