Gibson G R, McCartney A L, Rastall R A
Food Microbial Sciences Unit, School of Food Biosciences, The University of Reading, P. O. Box 226, Whiteknights, Reading RG6 6AP, UK.
Br J Nutr. 2005 Apr;93 Suppl 1:S31-4. doi: 10.1079/bjn20041343.
Acute gut disorder is a cause for significant medicinal and economic concern. Certain individual pathogens of the gut, often transmitted in food or water, have the ability to cause severe discomfort. There is a need to manage such conditions more effectively. The route of reducing the risk of intestinal infections through diet remains largely unexplored. Antibiotics are effective at inhibiting pathogens; however, these should not be prescribed in the absence of disease and therefore cannot be used prophylactically. Moreover, their indiscriminate use has reduced effectiveness. Evidence has accumulated to suggest that some of the health-promoting bacteria in the gut (probiotics) can elicit a multiplicity of inhibitory effects against pathogens. Hence, an increase in their numbers should prove effective at repressing pathogen colonisation if/when infectious agents enter the gut. As such, fortification of indigenous bifidobacteria/lactobacilli by using prebiotics should improve protection. There are a number of potential mechanisms for lactic acid bacteria to reduce intestinal infections. Firstly, metabolic endproducts such as acids excreted by these micro-organisms may lower the gut pH to levels below those at which pathogens are able to effectively compete. Also, many lactobacilli and bifidobacteria species are able to excrete natural antibiotics, which can have a broad spectrum of activity. Other mechanisms include an improved immune stimulation, competition for nutrients and blocking of pathogen adhesion sites in the gut. Many intestinal pathogens like type 1 fimbriated Escherichia coli, salmonellae and campylobacters utilise oligosaccharide receptor sites in the gut. Once established, they can then cause gastroenteritis through invasive and/or toxin forming properties. One extrapolation of the prebiotic concept is to simulate such receptor sites in the gut lumen. Hence, the pathogen is 'decoyed' into not binding at the host mucosal interface. The combined effects of prebiotics upon the lactic acid flora and anti-adhesive strategies may lead towards new dietary interventions against food safety agents.
急性肠道疾病是一个引起重大医学和经济关注的原因。肠道中的某些特定病原体，通常通过食物或水传播，有能力引起严重不适。更有效地管理此类情况很有必要。通过饮食降低肠道感染风险的途径在很大程度上仍未得到探索。抗生素在抑制病原体方面有效；然而，在没有疾病的情况下不应开具抗生素，因此不能用于预防。此外，它们的滥用降低了有效性。越来越多的证据表明，肠道中的一些促进健康的细菌（益生菌）可以对病原体产生多种抑制作用。因此，如果/当感染因子进入肠道时，增加它们的数量应该能有效抑制病原体的定植。因此，使用益生元强化本土双歧杆菌/乳酸杆菌应该能增强保护作用。乳酸菌减少肠道感染有多种潜在机制。首先，这些微生物分泌的代谢终产物如酸可能会将肠道pH值降低到病原体无法有效竞争的水平以下。此外，许多乳酸杆菌和双歧杆菌物种能够分泌天然抗生素，其具有广泛的活性。其他机制包括增强免疫刺激、竞争营养物质以及阻断肠道中病原体的黏附位点。许多肠道病原体，如1型菌毛大肠杆菌、沙门氏菌和弯曲杆菌，利用肠道中的寡糖受体位点。一旦定植，它们随后就可以通过侵袭性和/或产毒素特性引起肠胃炎。益生元概念的一个推断是在肠腔内模拟此类受体位点。因此，病原体被“诱骗”而不在宿主黏膜界面结合。益生元对乳酸菌群的综合作用以及抗黏附策略可能会带来针对食品安全因子的新饮食干预措施。
