Gorbach S L
Infection. 1982 Nov-Dec;10(6):379-84. doi: 10.1007/BF01642307.
Epidemiologic studies suggest that the incidence of colon cancer is influenced by environmental factors, especially diet. The high beef-high fat-low fiber diet of Western societies is associated with a high risk of colon cancer. The intestinal microflora may play a role in colon cancer by metabolic activation of procarcinogens in the lumen of the large bowel. The link between diet and colon cancer can be explained, in part, by the alterations in fecal bacterial enzyme activity induced by a Western-style diet. For example, fecal bacterial beta-glucuronidase, nitroreductase, azoreductase and steroid 7-alpha-dehydroxylase activities are increased in animals or humans consuming a high beef diet. These enzyme activities can be reduced by eating a grain diet, by the addition of Lactobacillus acidophilus to the diet, or by administration of low dose antibiotics. In experimental animals these three measures to reduce the activity of the microflora also produce few colon tumors in animals given the chemical carcinogen dimethylhydrazine. Further studies are needed to establish whether alterations in the metabolism of the colonic microflora can reduce the risk of large bowel cancer in humans.
流行病学研究表明，结肠癌的发病率受环境因素影响，尤其是饮食。西方社会高牛肉、高脂肪、低纤维的饮食与患结肠癌的高风险相关。肠道微生物群可能通过在大肠肠腔内对致癌物前体进行代谢激活，从而在结肠癌中发挥作用。饮食与结肠癌之间的联系，部分可以通过西式饮食引起的粪便细菌酶活性改变来解释。例如，食用高牛肉饮食的动物或人类，其粪便细菌β-葡萄糖醛酸酶、硝基还原酶、偶氮还原酶和类固醇7-α-脱羟基酶的活性会增加。通过食用谷物饮食、在饮食中添加嗜酸乳杆菌或给予低剂量抗生素，这些酶的活性可以降低。在实验动物中，这三种降低微生物群活性的措施，在给予化学致癌物二甲基肼的动物中也很少产生结肠肿瘤。需要进一步研究来确定结肠微生物群代谢的改变是否能降低人类患大肠癌的风险。
