Food Futures National Research Flagship, CSIRO Food and Nutritional Sciences, P.O. Box 10041, Adelaide BC 5000, Australia.
Benef Microbes. 2010 Nov;1(4):423-31. doi: 10.3920/BM2010.0041.
The metabolic end products of the large bowel microbiota contribute significantly to human health. After weaning to solid foods, some of the most important of these are the short chain fatty acids (SCFA) produced by the fermentation of undigested dietary components and endogenous secretions. The main SCFA are acetate, propionate and butyrate which have numerous documented effects promoting large bowel function. Of the major acids, butyrate seems especially important. It is a major metabolic fuel for colonocytes and promotes a normal phenotype in these cells, potentially lowering the risk of diseases such as colo-rectal cancer. Imbalances in the microbiota are thought to predispose to large bowel dysfunction and probiotics are being developed to correct this. However, most commercial products contain bacteria (lactobacilli and bifidobacteria) which are dominant species in milk-fed infants but have limited roles in adults. Prebiosis is defined usually by the specific stimulation of these bacteria. However, the end products of most probiotics do not include butyrate or propionate which raises questions about their effectiveness in promoting bowel health in adults. Resistant starch (RS) is a dietary fibre component and its fermentation generally favours butyrate production. Dietary RS intakes and faecal butyrate levels are high in populations at low risk of diet-related large bowel diseases. Conversely, RS intakes and faecal butyrate levels are very low in high risk groups. This raises the possibility that greater RS consumption could be of health benefit. RS is not regarded widely as a prebiotic but (according to the accepted definition) most forms show the requisite features in stimulating specific bacteria, giving raised total SCFA and butyrate levels and a consequent benefit to the host. Current efforts to improve public health through increasing RS consumption could be facilitated by greater recognition of its prebiotic role.
大肠菌群的代谢终产物对人体健康有重要贡献。在断奶后开始食用固体食物后，其中一些最重要的是未消化的饮食成分和内部分泌物发酵产生的短链脂肪酸 (SCFA)。主要的 SCFA 是乙酸盐、丙酸盐和丁酸盐，它们具有许多被记录的促进大肠功能的作用。在主要酸中，丁酸盐似乎尤为重要。它是结肠细胞的主要代谢燃料，并促进这些细胞的正常表型，可能降低结直肠癌等疾病的风险。微生物群的失衡被认为易导致大肠功能障碍，正在开发益生菌来纠正这种情况。然而，大多数商业产品都含有细菌（乳酸菌和双歧杆菌），这些细菌是母乳喂养婴儿中的主要物种，但在成人中作用有限。预生物通常被定义为对这些细菌的特定刺激。然而，大多数益生菌的终产物不包括丁酸盐或丙酸盐，这使得人们对它们在促进成人肠道健康方面的有效性产生了质疑。抗性淀粉 (RS) 是膳食纤维的一个组成部分，其发酵通常有利于丁酸盐的产生。在患与饮食相关的大肠疾病风险较低的人群中，RS 摄入量和粪便丁酸盐水平较高。相反，高危人群的 RS 摄入量和粪便丁酸盐水平非常低。这提出了一个可能性，即增加 RS 摄入量可能对健康有益。RS 通常不被认为是一种益生元，但（根据公认的定义）大多数形式在刺激特定细菌方面具有必要的特征，从而提高总 SCFA 和丁酸盐水平，并对宿主产生相应的益处。通过增加 RS 摄入量来改善公众健康的努力可以通过更广泛地认识到其益生元作用来促进。
