路過的就踩一下作者: yihaiqiu520 時間: 2009-11-20 21:55
益生元又稱化學益生素.作者: 山東畜牧人 時間: 2009-11-21 16:37
恩 不錯！對著2個概念更明確了。多謝作者: 給與陽光 時間: 2009-11-21 18:33
你所解釋的益生元是狹義的益生元，廣義的益生元包括低聚糖、微藻及天然植物等能促進益生菌增值的物質作者: playboy 時間: 2009-11-21 19:23
Prebiotics are non-digestible food ingredients that stimulate the growth and/or activity of bacteria in the digestive system which are beneficial to the health of the body. They were first identified and named by Marcel Roberfroid in 1995.[1] They are considered a functional food.
Typically, prebiotics are carbohydrates (such as oligosaccharides), but the definition does not preclude non-carbohydrates. The most prevalent forms of prebiotics are nutritionally classed as soluble fiber. To some extent, many forms of dietary fiber exhibit some level of prebiotic effect.
Roberfroid offered a refined definition in the 2007 Journal of Nutrition [2] 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 clarified that only two particular fructooligosaccharides fully meet this definition: oligofructose and inulin[3]. Caution may be in order when referring to other substances as "Prebiotic," and it is increasingly common to refer to other similar substances as "possible" or "likely" Prebiotics in order to distinguish.
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, are typically fermented more quickly in the right-side 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 left-side colon. Full-spectrum prebiotics provide the full range of molecular link-lenghts 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.[作者: playboy 時間: 2009-11-21 19:25
The prebiotic definition does not emphasize a specific bacterial group. Generally, however, it is assumed that a prebiotic should increase the number and/or activity of bifidobacteria and lactic acid bacteria. The importance of the bifidobacteria and the lactic acid bacteria (AKA lactobacillus or LABs) is that these groups of bacteria have several beneficial effects on the host, especially in terms of improving digestion (including enhancing mineral absorption[9]) and the effectiveness and intrinsic strength of the immune system.[10] A product that stimulates bifidobacteria is considered a bifidogenic factor. Some prebiotics may thus also act as a bifidogenic factor and vice versa, but the two concepts are not identical.[11]作者: playboy 時間: 2009-11-21 19:26
Traditional dietary sources of prebiotics include soybeans, inulin sources (such as Jerusalem artichoke, jicama, and chicory root), raw oats, unrefined wheat, unrefined barley and yacon. Some of the oligosaccharides that naturally occur in breast milk are believed to play an important role in the development of a healthy immune system in infants.
It is becoming more common to properly distinguish between prebiotic substances and the food that contains them. References to Almonds, honey and other foods (most commonly in promotional materials from growers of those foods) as "a prebiotic" are not accurate. No plant or food _is_ a prebiotic: Wheat, honey and many other foods _contain_ prebiotics to a greater or lesser extent, ranging from fairly large portions (chicory root, jerusalem artichoke) to only trace quantities (thousands of other plant-based foods). Referring to a food as "a prebiotic" is no more accurate than calling a food "a vitamin."
Jerusalem Artichoke is a frequently referred to as a rich source of prebiotic fiber. This is true, but it should be pointed out that jerusalem artichoke is NOT the traditional spiky green artichoke found in most groceries stores, but another plant altogether (and a far-from-common offering at most food merchants).
While there is no broad consensus on an ideal daily serving of prebiotics, recommendations typically range from 4-8g for general digestive health support, to 15g or more for those with active digetive disorders. Given an average 6g serving, below are the amounts of Prebiotic Foods Required to achieve a Daily Serving of Prebiotic Fiber
Those wishing to ensure sufficient prebiotic intake should carefully consider the prebiotic content of their diet, as well as what caloric/nutritive load comes along with it: e.g. eating 1.3 pounds of bananas daily is likely to provide an excess of calories & sugars/carbohydrates to the diet. Prebiotic fiber supplements with minimal caloric/fat/sugar load are also available.
Prebiotic oligosaccharides are increasingly added to foods for their health benefits. Some oligosaccharides that are used in this manner are fructooligosaccharides (FOS), xylooligosaccharides (XOS), polydextrose and galactooligosaccharides (GOS). Some monosaccharides such as tagatose are also used sometimes as prebiotics.[citation needed]
In petfood also mannooligosaccharides are being used for prebiotic purposes.
Again, one may wish to recall that Roberfroid, whom many consider the pre-eminent authority on Prebiotics[14], states that only two specific fructooligosaccharides - oligofructose and inulin - meet his seminal definition of "Prebiotic."[3]
Genetically engineering plants for the production of inulins has also become more prevalent [15].[16], despite the still limited insight into the immunological mechanisms activated by such food supplementation [17].作者: playboy 時間: 2009-11-21 19:27
Studies have demonstrated positive effects on calcium and other mineral absorption[18], immune system effectiveness[19], bowel pH, reduction of colorectal cancer risk[20], inflammatory bowel disorders (Crohn's Disease and Ulcerative Colitis) [21] and intestinal regularity.[citation needed] Recent human trials have reinforced the role of Prebiotics in preventing and possibly stopping early stage colon cancer.[22] It has been argued that many of these health effects emanate not just from bifidogenic function of prebiotics, but also from increased production of short-chain fatty acids by the stimulated beneficial bacteria. Thus food supplements specifically enhancing the growth of intestinal bacteria are widely recognized to be beneficial.
While research does clearly demonstrate that prebiotics lead to increased production of these SCFA's[23], more research is required to establish a direct causal connection. It has been argued that prebiotics are beneficial to Crohn's Disease through production of SCFAs to nourish the colon walls, and beneficial to Ulcerative Colitis through reduction of Hydrogen Sulfide gas due to reduction of sulfate-reducing bacteria, which do not thrive in the slightly acidic environment SCFAs create.
The immediate addition of substantial quantities of prebiotics to the diet may result in a temporary increase in gas, bloating or bowel movement. It has been argued that chronically low consumption of prebiotic-containing foods in the typical Western diet may exaggerate this effect.[citation needed]作者: playboy 時間: 2009-11-21 19:29
Probiotics are dietary supplements of live microorganisms thought to be healthy for the host organism. According to the currently adopted definition by FAO/WHO, probiotics are: "Live microorganisms which when administered in adequate amounts confer a health benefit on the host".[1] Lactic acid bacteria (LAB) and bifidobacteria are the most common types of microbes used as probiotics; but also certain yeasts and bacilli are available. Etymologically, the term appears to be a composite of the Latin preposition pro ("for") and the Greek adjective βιωτικός (biotic), the latter deriving from the noun βίος (bios, "life").[2]
At the start of the 20th century, probiotics were thought to beneficially affect the host by improving its intestinal microbial balance, thus inhibiting pathogens and toxin producing bacteria [3]. Today[when?] specific health effects are being investigated and documented including alleviation of chronic intestinal inflammatory diseases,[4] prevention and treatment of pathogen-induced diarrhea,[5] urogenital infections,[6] and atopic diseases.[作者: playboy 時間: 2009-11-21 19:30
Potential benefits
Experiments into the benefits of probiotic therapies suggest a range of potentially beneficial medicinal uses for probiotics. For many of the potential benefits, research is limited and only preliminary results are available. It should be noted that the effects described are not general effects of probiotics. Recent research on the molecular biology and genomics of Lactobacillus has focused on the interaction with the immune system, anti-cancer potential, and potential as a biotherapeutic agent in cases of antibiotic-associated diarrhoea, travellers' diarrhoea, pediatric diarrhoea, inflammatory bowel disease and irritable bowel syndrome.[21]
All effects can only be attributed to the individual strain(s) tested. Testing of a supplement does not indicate benefit from any other strain of the same species, and testing does not indicate benefit from the whole group of LAB (or other probiotics).[22]
[edit] Managing lactose intolerance
As lactic acid bacteria actively convert lactose into lactic acid, ingestion of certain active strains may help lactose intolerant individuals tolerate more lactose than what they would have otherwise.[23] In practice probiotics are not specifically targeted for this purpose, as most are relatively low in lactase activity as compared to the normal yogurt bacteria.
[edit] Prevention of colon cancer
In laboratory investigations, some strains of LAB (Lactobacillus bulgaricus) have demonstrated anti-mutagenic effects thought to be due to their ability to bind with heterocyclic amines, which are carcinogenic substances formed in cooked meat.[24] Animal studies have demonstrated that some LAB can protect against colon cancer in rodents, though human data is limited and conflicting.[25] Most human trials have found that the strains tested may exert anti-carcinogenic effects by decreasing the activity of an enzyme called β-glucuronidase[25] (which can generate carcinogens in the digestive system). Lower rates of colon cancer among higher consumers of fermented dairy products have been observed in some population studies.[23]
[edit] Lowering cholesterol
Animal studies have demonstrated the efficacy of a range of LAB to be able to lower serum cholesterol levels, presumably by breaking down bile in the gut, thus inhibiting its reabsorption (which enters the blood as cholesterol). Some, but not all human trials have shown that dairy foods fermented with specific LAB can produce modest reductions in total and LDL cholesterol levels in those with normal levels to begin with, however trials in hyperlipidemic subjects are needed.[23]
[edit] Lowering blood pressure
Several small clinical trials have shown that consumption of milk fermented with various strains of LAB can result in modest reductions in blood pressure. It is thought that this is due to the ACE inhibitor-like peptides produced during fermentation.[23]
[edit] Improving immune function and preventing infections
LAB are thought to have several presumably beneficial effects on immune function. They may protect against pathogens by means of competitive inhibition (i.e., by competing for growth) and there is evidence to suggest that they may improve immune function by increasing the number of IgA-producing plasma cells, increasing or improving phagocytosis as well as increasing the proportion of T lymphocytes and Natural Killer cells.[26][27] Clinical trials have demonstrated that probiotics may decrease the incidence of respiratory tract infections[28] and dental caries in children.[29] LAB foods and supplements have been shown to be aid in the treatment and prevention of acute diarrhea, and in decreasing the severity and duration of rotavirus infections in children and travelers' diarrhea in adults.[26][27]
[edit] Helicobacter pylori
LAB are also thought to aid in the treatment of Helicobacter pylori infections (which cause peptic ulcers) in adults when used in combination with standard medical treatments. However more studies are required into this area.[30]
[edit] Antibiotic-associated diarrhea
Antibiotic-associated diarrhea (AAD) results from an imbalance in the colonic microbiota caused by antibiotic therapy. Microbiota alteration changes carbohydrate metabolism with decreased short-chain fatty acid absorption and an osmotic diarrhea as a result. Another consequence of antibiotic therapy leading to diarrhea is overgrowth of potentially pathogenic organisms such as Clostridium difficile.
Probiotic treatment can reduce the incidence and severity of AAD as indicated in several meta-analyses.[31][32][33][34][35][34] However, further documentation of these findings through randomized, double blind, placebo-controlled trials are warranted. Efficacy of probiotic AAD prevention is dependent on the probiotic strain(s) used and on the dosage.[36][37] Up to a 50% reduction of AAD occurrence has been found.[35] No side-effects have been reported in any of these studies. Caution should, however, be exercised when administering probiotics to immunocompromised individuals or patients who have a compromised intestinal barrier.
[edit] Reducing inflammation
LAB foods and supplements have been found to modulate inflammatory and hypersensitivity responses, an observation thought to be at least in part due to the regulation of cytokine function.[26] Clinical studies suggest that they can prevent reoccurrences of inflammatory bowel disease in adults,[26] as well as improve milk allergies.[38] They are not effective for treating eczema, a persistent skin inflammation.[39]. How probiotics counteract immune system overactivity remains unclear, but a potential mechanism is desensitization of so-called T lymphocytes, an important compenent of the immune system, towards pro-inflammatory stimuli [40].
[edit] Improving mineral absorption
It is hypothesized that probiotic lactobacilli may help correct malabsorption of trace minerals, found particularly in those with diets high in phytate content from whole grains, nuts, and legumes.[41]
[edit] Preventing harmful bacterial growth under stress
In a study done to see the effects of stress on intestinal flora, rats that were fed probiotics had little occurrence of harmful bacteria latched onto their intestines compared to rats that were fed sterile water.[42]
[edit] Irritable bowel syndrome and colitis
B. infantis 35624, sold as Align, was found to improve some symptoms of irritable bowel syndrome in women in a recent study.[43] Another probiotic bacterium, Lactobacillus plantarum 299v, was also found to be effective in reducing IBS symptoms.[44] Additionally, a probiotic formulation, VSL#3, was found to be safe in treating ulcerative colitis, though efficacy in the study was uncertain.[45] Bifidobacterium animalis DN-173 010 may help.[46]
[edit] Managing urogenital health
Several in vitro studies have revealed probiotics' potential in relieving urinary tract infections[47] and bacterial vaginosis.[48] Results have been varied on these studies, and in vivo studies are still required in this area to determine efficacy.作者: playboy 時間: 2009-11-21 19:32
Adverse effects
There is no published evidence that probiotic supplements are able to completely replace the body’s natural flora when these have been killed off; indeed bacterial levels in feces disappear within days when supplementation ceases.[15] While the oral use of probiotics is considered safe and even recommended by the World Health Organization (WHO) under specific guidelines,[1] in some specific situations (such as critically ill patients) they could be potentially harmful. In a therapeutic clinical trial conducted by M. Besselink and colleagues in The Netherlands, the consumption of a cocktail containing genetically modified strains of probiotic bacteria, increased the death rate of patients with acute pancreatitis[16]. Probiotics have been shown to be beneficial for other types of patients[17][18].
In a clinical trial conducted at the University of Western Australia, aimed at showing the effectiveness of probiotics in reducing childhood allergies, Dr Susan Prescott and her colleagues gave 178 children either a probiotic or a placebo for the first six months of their life, those given the good bacteria were more, not less, likely to develop a sensitivity to allergens.[19]
Some hospitals have reported treating lactobacillus septicaemia which is a potentially fatal disease caused by the consumption of probiotics by people with lowered immune systems or who are already very ill.[19][20]作者: xxc1963 時間: 2009-11-21 20:56
講的非常好！這一大堆外文是什么意思啊作者: playboy 時間: 2009-11-21 20:57
英文，更詳細準確！作者: 韓小榮 時間: 2009-11-23 16:14 那要看是商標還是名稱呢，現在很多企業亂用的作者: 虛竹 時間: 2010-1-2 19:09
還是翻譯成我們的母語吧
那要看是商標還是名稱呢，現在很多企業亂用的