Intestinal Microflora Research for the 21st Century

Abstract

Dietary modulation of the human gut microbiota is a topical area of nutritional sciences. This is driven by the fact that the gastrointestinal tract, particularly the colon, is very heavily populated. Undoubtedly, certain gut species are pathogenic and may be involved in the onset of acute and chronic disorder. However, most bacteria in the gut are benign, with the possibility that some groups are beneficial. Bifidobacteria and lactobacilli are thought to belong to this latter category and are common targets for dietary intervention that improves health. Dietary modulation of the human gut microflora by functional foods such as probiotics and prebiotics is designed to improve human health. A probiotic is a live microbial feed supplement, whereas a prebiotic is a non viable food ingredient selectively metabolised by intestinal bacterial species seen as beneficial. Examples of probiotics are lactobacilli and bifidobacteria, given in fermented milks or as lyophilised forms. Fructo-oligosaccharides, lactulose and galacto-oligosaccharides are all popular prebiotics in Europe. These have been shownin vivoto stimulate numbers of bifidobacteria in faecal samples. Many more types exist in Japan. Bifidobacteria and lactobacilli are thought to contribute many health promoting benefits towards the host. These include increased resistance to pathogenic bacteria, lowering blood ammonia, increased stimulation of the immune response and a reduction in the risk of cancer. New functional food developments are set, more than ever, to exploit probiotics and prebiotics. However, it is important that their use is underpinned by robust scientific principles and technologies.