Prebiotic (nutrition)

The definition of prebiotics and the food ingredients that can fall under this classification, has evolved since its first definition in 1995. In its earliest definition, the term prebiotics was used to refer to non-digestible food ingredients that were beneficial to the host through their selective stimulation of specific bacteria within the colon. Further research has suggested that selective stimulation has not been scientifically demonstrated. As a result of research suggesting that prebiotics could impact microorganisms outside of the colon, in 2016 the International Scientific Association for Probiotics and Prebiotics (ISAPP) produced the following definition of prebiotics: a substrate that is selectively used by a host microorganism to produce a health benefit. Compounds that can be classified as prebiotics must also meet the following criteria: Based on the previous classifications, plant-derived carbohydrate compounds called oligosaccharides as well as resistant starch are the main source of prebiotics that have been identified. Specifically, fructans and galactans are two oligosaccharide sources which have been found to stimulate the activity and growth of beneficial bacterial colonies in the gut. Other dietary fibers also fit the definition of prebiotics, such as pectin, beta-glucans, and xylooligosaccharides. The European Food Safety Authority (EFSA), the regulatory agency for product labeling, differentiates between "prebiotic" and "dietary fiber", stating that "a cause and effect relationship has not been established between the consumption of the food constituents which are the subject of the health claims and a beneficial physiological effect related to increasing numbers of gastrointestinal microbiota". Consequently, under EFSA rules individual ingredients cannot be labeled as prebiotics, but only as dietary fiber and with no implication of health benefits. == Function ==

When the prebiotic concept was first introduced in 1995, the primary focus was on the effects that prebiotics confer on Bifidobacteria and Lactobacillus. With improved mechanistic techniques in recent years, the current prebiotic targets have expanded to a wider range of microbes, including Roseburia spp., Eubacterium spp., Akkermansia spp., Christensenella spp., Propionibacterium spp. and Faecalibacterium spp. These bacteria have been highlighted as key probiotics and beneficial gut bacteria as they may have several beneficial effects on the host in terms of improving digestion (including but not limited to enhancing mineral absorption) and the effectiveness and intrinsic strength of the immune system. Both Bifidobacteria and Lactobacillus have been shown to have differing prebiotic specificity and to selectively ferment prebiotic fiber based on the enzymes characteristic of the bacterial population. Thus, Lactobacilli prefer inulin and fructooligosaccharides, while Bifidobacteria display specificity for inulin, fructooligosaccharides, xylooligosaccharides and galactooligosaccharides. ==Sources==

Preliminary research has demonstrated potential effects on calcium and other mineral absorption, immune system effectiveness, bowel acidity, reduction of colorectal cancer risk, inflammatory bowel disease (Crohn's disease or ulcerative colitis), hypertension and defecation frequency. Prebiotics may be effective in decreasing the number of infectious episodes needing antibiotics and the total number of infections in children aged 0–24 months. No good evidence shows that prebiotics are effective in preventing or treating allergies. While research demonstrates that prebiotics lead to increased production of short-chain fatty acids (SCFA), more research is required to establish a direct causal connection. Prebiotics may be beneficial to inflammatory bowel disease or Crohn's disease through production of SCFA as nourishment for colonic walls, and mitigation of ulcerative colitis symptoms. The sudden addition of substantial quantities of prebiotics to the diet may result in an increase in fermentation, leading to increased gas production, bloating or bowel movement. Production of SCFA and fermentation quality are reduced during long-term diets of low fiber intake. Until bacterial flora are gradually established to rehabilitate or restore intestinal bacteria, nutrient absorption may be impaired and colonic transit time temporarily increased with a rapid addition of higher prebiotic intake. Genetic modification Genetically modified plants have been created in research labs with upregulated inulin production. ==See also==