Clausen M R, Bonnén H, Mortensen P B
Department of Medicine A, Rigshospitalet, University of Copenhagen, Denmark.
Gut. 1991 Aug;32(8):923-8. doi: 10.1136/gut.32.8.923.
Short chain (C2-C6) fatty acids are produced in the colon through bacterial fermentation of mainly dietary fibre. Butyrate (C4) possesses antineoplastic effects on human colon carcinoma cells, and epidemiological studies indicate that high fibre diets may reduce the incidence of colorectal cancer. The role of dietary fibre during colorectal carcinogenesis might therefore be related to its fermentation to butyrate. Faecal concentrations of total short chain fatty acids and concentrations and ratios of the individual C2-C6 fatty acids did not differ between 16 healthy controls, 17 patients with colonic adenomas, and 17 patients with colonic cancer. Comparison of the molar production velocities (mmol/l.hour) of total and individual short chain fatty acids from glucose, ispagula, wheat bran, and albumin in six and 24 hour faecal incubations showed no differences. The ratio of butyrate production to total short chain fatty acid production from fibre, however, was reduced in patients with colonic cancer and adenomas compared with healthy controls (ispagula, six hours: 6.4, 7.6, and 11.5% respectively, p = 0.005 and 24 hour: 9.1, 9.9, and 15.4%, p = 0.002; wheat bran, six hours: 9.9, 10.2, and 14.7% respectively, p = 0.06 and 24 hours: 15.1, 16.8, and 21.0%, p = 0.01). It may be that the low ratios of colonic butyrate formation combined with low fibre diets increase the risk of colonic neoplasia.
短链（C2 - C6）脂肪酸主要通过膳食纤维的细菌发酵在结肠中产生。丁酸（C4）对人结肠癌细胞具有抗肿瘤作用，流行病学研究表明高纤维饮食可能降低结直肠癌的发病率。因此，膳食纤维在结直肠癌发生过程中的作用可能与其发酵生成丁酸有关。16名健康对照者、17名结肠腺瘤患者和17名结肠癌患者的粪便中总短链脂肪酸浓度以及各C2 - C6脂肪酸的浓度和比例并无差异。在6小时和24小时粪便培养中，比较葡萄糖、卵叶车前、麦麸和白蛋白生成总短链脂肪酸及各短链脂肪酸的摩尔生成速度（mmol/升·小时），未发现差异。然而，与健康对照者相比，结肠癌和腺瘤患者中纤维产生的丁酸产量与总短链脂肪酸产量的比值降低（卵叶车前，6小时：分别为6.4%、7.6%和11.5%，p = 0.005；24小时：9.1%、9.9%和15.4%，p = 0.002；麦麸，6小时：分别为9.9%、10.2%和14.7%，p = 0.06；24小时：15.1%、16.8%和21.0%，p = 0.01）。可能是结肠中丁酸生成比例低以及低纤维饮食增加了结肠肿瘤形成的风险。
