Wong Julia M W, de Souza Russell, Kendall Cyril W C, Emam Azadeh, Jenkins David J A
Clinical Nutrition and Risk Factor Modification Center, St Michael's Hospital, Toronto, Ont, Canada.
J Clin Gastroenterol. 2006 Mar;40(3):235-43. doi: 10.1097/00004836-200603000-00015.
Interest has been recently rekindled in short chain fatty acids (SCFAs) with the emergence of prebiotics and probiotics aimed at improving colonic and systemic health. Dietary carbohydrates, specifically resistant starches and dietary fiber, are substrates for fermentation that produce SCFAs, primarily acetate, propionate, and butyrate, as end products. The rate and amount of SCFA production depends on the species and amounts of microflora present in the colon, the substrate source and gut transit time. SCFAs are readily absorbed. Butyrate is the major energy source for colonocytes. Propionate is largely taken up by the liver. Acetate enters the peripheral circulation to be metabolized by peripheral tissues. Specific SCFA may reduce the risk of developing gastrointestinal disorders, cancer, and cardiovascular disease. Acetate is the principal SCFA in the colon, and after absorption it has been shown to increase cholesterol synthesis. However, propionate, a gluconeogenerator, has been shown to inhibit cholesterol synthesis. Therefore, substrates that can decrease the acetate: propionate ratio may reduce serum lipids and possibly cardiovascular disease risk. Butyrate has been studied for its role in nourishing the colonic mucosa and in the prevention of cancer of the colon, by promoting cell differentiation, cell-cycle arrest and apoptosis of transformed colonocytes; inhibiting the enzyme histone deacetylase and decreasing the transformation of primary to secondary bile acids as a result of colonic acidification. Therefore, a greater increase in SCFA production and potentially a greater delivery of SCFA, specifically butyrate, to the distal colon may result in a protective effect. Butyrate irrigation (enema) has also been suggested in the treatment of colitis. More human studies are now needed, especially, given the diverse nature of carbohydrate substrates and the SCFA patterns resulting from their fermentation. Short-term and long-term human studies are particularly required on SCFAs in relation to markers of cancer risk. These studies will be key to the success of dietary recommendations to maximize colonic disease prevention.
随着旨在改善结肠和全身健康的益生元和益生菌的出现，人们最近对短链脂肪酸（SCFAs）的兴趣再次被点燃。膳食碳水化合物，特别是抗性淀粉和膳食纤维，是发酵的底物，其发酵产生SCFAs作为终产物，主要是乙酸盐、丙酸盐和丁酸盐。SCFAs的产生速率和量取决于结肠中存在的微生物群落的种类和数量、底物来源以及肠道转运时间。SCFAs易于吸收。丁酸盐是结肠细胞的主要能量来源。丙酸盐主要被肝脏摄取。乙酸盐进入外周循环，由外周组织进行代谢。特定的SCFAs可能会降低患胃肠道疾病、癌症和心血管疾病的风险。乙酸盐是结肠中的主要SCFA，吸收后已显示会增加胆固醇合成。然而，丙酸盐作为一种糖异生剂，已显示会抑制胆固醇合成。因此，能够降低乙酸盐：丙酸盐比例的底物可能会降低血脂，并可能降低心血管疾病风险。丁酸盐因其在滋养结肠黏膜以及预防结肠癌方面的作用而受到研究，它通过促进转化结肠细胞的细胞分化、细胞周期停滞和凋亡；抑制组蛋白脱乙酰酶，并由于结肠酸化减少初级胆汁酸向次级胆汁酸的转化。因此，SCFAs产量的更大增加以及可能向远端结肠输送更多的SCFAs，特别是丁酸盐，可能会产生保护作用。丁酸盐灌肠也被建议用于治疗结肠炎。现在需要更多的人体研究，特别是考虑到碳水化合物底物的多样性以及它们发酵产生的SCFA模式。尤其需要关于SCFAs与癌症风险标志物关系的短期和长期人体研究。这些研究对于最大化结肠疾病预防的饮食建议的成功至关重要。
