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 gut flora 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 gut related candidiasis. Claims are made that probiotics strengthen the immune system.
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.Contents
1.1 Side effects
2 Potential Benefits
7 See also
8 External links
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.Side effects,
Treatment with probiotics, like any medicine, may include a condition called excessive drainage syndrome, which includes headache, diarrhea, bloating, or constipation. Another commonly reported side effect is intestinal gas. To reduce the side effects it is recommended to lower the supplement dosage, or pretreat with colon hydrotherapy, or stool softeners and fiber as tolerated or advised by a healthcare professional.
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.
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. Animal studies have demonstrated that LAB can protect against colon cancer in rodents, though human data is limited and conflicting. Most human trials have found that LAB may exert anti-carcinogenic effects by decreasing the activity of an enzyme called ß-glucuronidase (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.
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.
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.
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. Clinical trials have demonstrated that probiotics may decrease the incidence of respiratory tract infections and dental caries in children 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. 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.
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. Clinical studies suggest that they can prevent reoccurrences of inflammatory bowel disease in adults, as well as improve milk allergies and decrease the risk of atopic eczema in children.
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.
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 little occurrence of harmful bacteria latched onto their intestines compared to rats that were fed sterile water.
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. Another probiotic bacterium, Lactobacillus plantarum 299V, was also found to be effective in reducing IBS symptoms. Additionally, a probiotic formulation, VSL3, was found to be effective in treating ulcerative colitis
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.
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:Bifidobacterium animalis subsp. lactis
There is currently only one species of yeast used as a probiotic:
Some commonly used bacteria in products, but without probiotic effect:
Some other bacteria mentioned in probiotic products:
Lactobacillus bifidus - became new genus Bifidobacterium
Lactobacillus caucasicus, a fantasy name, as no species with this name exists.
Some fermented products containing similar (often not proven to have a probiotic or health effect) lactic acid bacteria include:
More studies of probiotics have been done in Europe than in the United States, which is reflected in the fact that the leading manufacturers of probiotic supplements (e.g. Danone) are presently based in Europe. Some mainstream researchers in Europe as well as in the United States are skeptical of some of the claims made for probiotics. Their reasons include the following considerations:
The studies done in support of probiotics are mostly anecdotal or heavily reliant on test-tube experimentation rather than on clinical trials in human subjects. As of 2000, relatively few strains of probiotic bacteria have been shown to have clinical value. These strains are helpful in treating milk allergy and irritable bowel syndrome in humans, and in improving resistance to a yeast called Candida in immunocompromised mice.
The basic concept of probiotics is based on a misunderstanding of the role of microflora in the human digestive tract.
It is difficult to see how bacteria taken by mouth can survive the process of human digestion (though research shows that they do, in fact, survive ).
At present, only two species of lactobacilli, L. GG and L. plan-tarum 299v, have been shown to be able to colonize the human gut.
Supporters of probiotics emphasize two types of bacteria, the lactobacilli and the bifidobacteria, and virtually ignore the hundreds of other species that live in the intestines.