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Prebiotics is a general term to refer to chemicals that induce the growth or activity of microorganisms (e.g., bacteria and fungi) that contribute to the well-being of their host. The most common example is in the gastrointestinal tract, where prebiotics can alter the composition of organisms in the gut microbiome. However, in principle it is a more general term that can refer to other areas of the body as well. For example, certain hand moisturizers have been proposed to act as prebiotics to improve the activity or composition of the skin microbiota. In diet, prebiotics are typically non-digestible fiber compounds that pass undigested through the upper part of the gastrointestinal tract and stimulate the growth or activity of advantageous bacteria that colonize the large bowel by acting as substrate for them. They were first identified and named by Marcel Roberfroid in 1995. As a functional food component, prebiotics, like probiotics, are conceptually intermediate between foods and drugs. Depending on the jurisdiction, they typically receive an intermediate level of regulatory scrutiny, in particular of the health claims made concerning them. ==Definition== Roberfroid offered a refined definition in the March 2007 ''Journal of Nutrition'' stating: "A prebiotic is a selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora that confers benefits upon host well-being and health." Additionally, in his 2007 revisit of prebiotics, Roberfroid stated that only two particular prebiotics then fully met this definition: trans-galactooligosaccharide and inulin. Other dietary fibers also fit the definition of prebiotics as developed by Roberfroid such as Larch arabinogalactin (LAG), resistant starch, pectin, beta-glucans, and Xylooligosaccharides (XOS). Researchers now also focus on the distinction between short-chain, long-chain, and full-spectrum prebiotics. "Short-chain" prebiotics, e.g. oligofructose, contain 2–8 links per saccharide molecule and are typically fermented more quickly in the ascending colon of the colon providing nourishment to the bacteria in that area. Longer-chain prebiotics, e.g. inulin, contain 9-64 links per saccharide molecule, and tend to be fermented more slowly, nourishing bacteria predominantly in the descending colon. Full-spectrum prebiotics provide the full range of molecular link-lengths from 2-64 links per molecule, and nourish bacteria throughout the colon, e.g. Oligofructose-Enriched Inulin (OEI). The majority of research done on prebiotics is based on full-spectrum prebiotics, typically using OEI as the research substance. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Prebiotic (nutrition)」の詳細全文を読む スポンサード リンク
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