Probiotic

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Probiotics are dietary supplements containing potentially beneficial bacteria or yeast, with lactic acid bacteria (LAB) as the most common microbes used. LAB have been used in the food industry for many years, because they are able to convert sugars (including lactose) and other carbohydrates into lactic acid. This not only provides the characteristic sour taste of fermented dairy foods such as yogurt, but acts as a preservative, by lowering the pH and creating fewer opportunities for spoilage organisms to grow.

Probiotic bacterial cultures are intended to assist the body's naturally occurring flora within the digestive tract to reestablish themselves. They are sometimes recommended by doctors, and, more frequently, by nutritionists, after a course of antibiotics, or as part of the treatment for candidiasis. Many probiotics are present in natural sources such as lactobacillus in yogurt and sauerkraut. Claims are made that probiotics strengthen the immune system.<ref name="Sanders">Sanders ME. Considerations for use of probiotic bacteria to modulate human health. J Nutr. 2000;130:384S-390S. Entrez PubMed 10721912</ref>

The rationale for probiotics is that the body contains a miniature ecology of microbes, collectively known as the gut flora. The number of bacterial types can be thrown out of balance by a wide range of circumstances including the use of antibiotics or other drugs, excess alcohol, stress, disease, exposure to toxic substances, or even the use of antibacterial soap. In cases like these, the bacteria that work well with our bodies (see symbiosis) may decrease in number, an event which allows harmful competitors to thrive, to the detriment of our health.

Maintenance of a healthy gut flora is, however, dependent on many factors, especially the quality of food intake. Including a significant proportion of prebiotic foods in the diet has been demonstrated to support a healthy probiotic flora and may be a more effective and sustainable means of achieving the desirable health benefits promised by probiotics.

1 Effects
2 Potential Benefits
3 Synbiotics
4 Types
5 References
6 See also
7 External links

[edit] Effects

There is no published evidence that probiotic supplements are able to replace the body’s natural flora when these have been killed off; indeed bacterial levels in feces disappear within days when supplementation ceases. There is evidence, however, that probiotics do form beneficial temporary colonies which may assist the body in the same functions as the natural flora, while allowing the natural flora time to recover from depletion. The probiotic strains are then progressively replaced by a naturally developed gut flora. Hence, probiotics have been defined as correctives of the ecoorgan. If the conditions which originally caused damage to the natural gut flora persist, the benefits obtained from probiotic supplements will be short lived.

[edit] 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.

Managing Lactose Intolerance: Because LAB convert lactose into lactic acid, their ingestion may help lactose intolerant individuals tolerate more lactose than what they would have otherwise.<ref name="Sanders"/>

Prevention of Colon Cancer: In laboratory investigations, LAB have demonstrated anti-mutagenic effects thought to be due to their ability to bind with heterocylic amines; carcinogenic substances formed in cooked meat.<ref name="Wollowski">Wollowski I, Rechkemmer G, Pool-Zobel BL. Protective role of probiotics and prebiotics in colon cancer. Am J Clin Nutr. 2001;73:451S-455S. Entrez PubMed 11157356</ref> Animal studies have demonstrated that LAB can protect against colon cancer in rodents, though human data is limited and conflicting.<ref name="Brady">Brady LJ, Gallaher DD, Busta FF. The role of probiotic cultures in the prevention of colon cancer. J Nutr. 2000;130:410S-414S. Entrez PubMed 10721916</ref> Most human trials have found that LAB may exert anti-carcinogenic effects by decreasing the activity of an enzyme called ß-glucuronidase<ref name="Brady"/> (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.<ref name="Sanders"/>

Cholesterol Lowering: 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 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.<ref name="Sanders"/>

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.<ref name="Sanders"/>

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.<ref name="Reid_Jass_Sebulsky">Reid G, Jass J, Sebulsky MT, McCormick JK. Potential uses of probiotics in clinical practice. Clin Microbiol Rev. 2003;16:658-72. Entrez PubMed 14557292</ref><ref name="Ouwehand_Salminen_Isolauri">Ouwehand AC, Salminen S, Isolauri E. Probiotics: an overview of beneficial effects. Antonie Van Leeuwenhoek. 2002;82:279-89. Entrez PubMed 12369194</ref> Clinical trials have demonstrated that probiotics may decrease the incidence of respiratory tract infections<ref>Hatakka K, Savilahti E, Ponka A, Meurman JH, Poussa T, Nase L, Saxelin M, Korpela R. Effect of long term consumption of probiotic milk on infections in children attending day care centres: double blind, randomised trial. BMJ. 2001;322:1327 Entrez PubMed 11387176</ref> and dental caries in children<ref>Nase L, Hatakka K, Savilahti E, Saxelin M, Ponka A, Poussa T, Korpela R, Meurman JH. Effect of long-term consumption of a probiotic bacterium, Lactobacillus rhamnosus GG, in milk on dental caries and caries risk in children. Caries Res. 2001;35:412-20. Entrez PubMed 11799281</ref> as well as aid in the treatment of Helicobacter pylori infections (which cause peptic ulcers) in adults when used in combination with standard medical treatments.<ref>Hamilton-Miller JM. The role of probiotics in the treatment and prevention of Helicobacter pylori infection. Int J Antimicrob Agents. 2003;22:360-366. Entrez PubMed 14522098</ref> LAB foods and supplements have been shown to be effective in the treatment and prevention of acute diarrhea; decreasing the severity and duration of rotavirus infections in children as well as antibiotic associated and travelers diarrhea in adults.<ref name="Reid_Jass_Sebulsky"/><ref name="Ouwehand_Salminen_Isolauri"/><ref>Cremonini F, Di Caro S, Nista EC, Bartolozzi F, Capelli G, Gasbarrini G, Gasbarrini A. Meta-analysis: the effect of probiotic administration on antibiotic-associated diarrhoea. Aliment Pharmacol Ther. 2002;16:1461-1467 Entrez PubMed 12182746</ref>

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.<ref name="Reid_Jass_Sebulsky"/> Clinical studies suggest that they can prevent reoccurrences of inflammatory bowel disease in adults,<ref name="Reid_Jass_Sebulsky"/> as well as improve milk allergies<ref>Kirjavainen PV, Salminen SJ, Isolauri E Probiotic bacteria in the management of atopic disease: underscoring the importance of viability. J Pediatr Gastroenterol Nutr. 2003;36:223-227 Entrez PubMed 12548058</ref> and decrease the risk of atopic eczema in children.<ref>Kalliomaki M, Salminen S, Poussa T, Arvilommi H, Isolauri E. Probiotics and prevention of atopic disease: 4-year follow-up of a randomised placebo-controlled trial. Lancet. 2003;361:1869-1871. Entrez PubMed 12788576</ref>

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.<ref>Famularo G, De Simone C, Pandey V, Sahu AR, Minisola G. Probiotic lactobacilli: an innovative tool to correct the malabsorption syndrome of vegetarians? Med Hypotheses. 2005;65(6):1132-5. Entrez PubMed 16095846</ref>

Prevents Harmful Bacterial Growth Under Stress: In a study done to see the effects of stress on intestinal flora, rats that were fed probiotics had no occurrence of harmful bacteria latched onto their intestines compared to rats that were fed sterile water.<ref>Hitti, Miranda (April 25, 2006). Probiotics May Help Stressed Gut. WebMD. Retrieved on 2006-10-24.</ref>

[edit] Synbiotics

Although use of probiotic formulations may well help in achieving these benefits, it is also possible to increase and maintain a healthy bacterial gut flora by increasing the amounts of prebiotics in the diet such as inulin, raw oats, and unrefined wheat.

As probiotics are mainly active in the small intestine and prebiotics are only effective in the large intestine, the combination of the two may give a synergistic effect. Appropriate combinations of pre- and probiotics are synbiotics.

Synbiotics have also been defined as metabolites produced by ecoorgan or by synergistic action of prebiotics and probiotics e.g. short chain fatty acids, other fatty acids, amino acids, peptides, polyamines, carbohydrates, vitamins, numerous antioxidants and phytosterols, growth factors, coagulation factors, various signal molecules such as cytokine-like bacteriokines.

[edit] Types

The most common form for probiotics are dairy products and probiotic fortified foods. However, tablets and capsules containing the bacteria in freeze dried form are also available.

Some common probiotics include various species of the genera Bifidobacterium and Lactobacillus such as: