Nutrition and Epigenetics Group, Division of Vascular Health, Rowett Institute of Nutrition and Health, University of Aberdeen, Bucksburn, Aberdeen, UK.
J Inherit Metab Dis. 2011 Feb;34(1):101-9. doi: 10.1007/s10545-010-9128-0. Epub 2010 Jun 11.
Inappropriate diet may contribute to one third of cancer deaths. Folates, a group of water-soluble B vitamins present in high concentrations in green, leafy vegetables, maintain DNA stability through their ability to donate one-carbon units for cellular metabolism. Folate deficiency has been implicated in the development of several cancers, including cancer of the colorectum, breast, ovary, pancreas, brain, lung and cervix. Generally, data from the majority of human studies suggest that people who habitually consume the highest level of folate, or with the highest blood folate concentrations, have a significantly reduced risk of developing colon polyps or cancer. However, an entirely protective role for folate against carcinogenesis has been questioned, and recent data indicate that an excessive intake of synthetic folic acid (from high-dose supplements or fortified foods) may increase human cancers by accelerating growth of precancerous lesions. Nonetheless, on balance, evidence from the majority of human studies indicates that dietary folate is genoprotective against colon cancer. Suboptimal folate status in humans is widespread. Folate maintains genomic stability by regulating DNA biosynthesis, repair and methylation. Folate deficiency induces and accelerates carcinogenesis by perturbing each of these processes. This review presents recent evidence describing how these mechanisms act, and interact, to modify colon cancer risk.
饮食不当可能导致三分之一的癌症死亡。叶酸是一组水溶性 B 族维生素，在绿叶蔬菜中含量很高，通过提供一碳单位来维持 DNA 的稳定性，从而参与细胞代谢。叶酸缺乏与几种癌症的发生有关，包括结直肠癌、乳腺癌、卵巢癌、胰腺癌、脑癌、肺癌和宫颈癌。一般来说，来自大多数人群研究的数据表明，习惯性摄入最高水平叶酸或血液叶酸浓度最高的人群，结肠息肉或癌症的发病风险显著降低。然而，叶酸对致癌作用的完全保护作用受到质疑，最近的数据表明，过量摄入合成叶酸（来自高剂量补充剂或强化食品）可能通过加速癌前病变的生长而增加人类癌症的风险。尽管如此，来自大多数人群研究的证据表明，饮食中的叶酸对结肠癌具有遗传保护作用。人类叶酸的营养状况不理想是普遍存在的。叶酸通过调节 DNA 生物合成、修复和甲基化来维持基因组的稳定性。叶酸缺乏通过扰乱这些过程中的每一个过程来诱导和加速致癌作用。这篇综述介绍了最近的证据，描述了这些机制如何作用并相互作用以改变结肠癌的风险。
