Description of Probiotics

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Probiotics are defined as live microorganisms, including Lactobacillus species, Bifidobacterium species and yeasts, that may beneficially affect the host upon ingestion by improving the balance of the intestinal microflora. The dietary use of live microorganisms has a long history. Mention of cultured dairy products is found in the Bible and the sacred books of Hinduism. Soured milks and cultured dairy products, such as kefir, koumiss, leben and dahi, were often used therapeutically before the existence of microorganisms was recognized. The use of microorganisms in food fermentation is one of the oldest methods for producing and preserving food. Much of the world depends upon various fermented foods that are staples in the diet.±¾ÎÄÀ´×Ô http://hexu.info ºÍ¡¤ìã¡¤¾«¡¤´â
Élie Metchnikoff, the father of modern immunology, spoke highly about the possible health benefits of the lactic acid-bacteria (LAB) Lactobacillus bulgaricus and Streptococcus thermophilus in his writings at the turn of the last century. He wrote in his book, The Prolongation of Life, that consumption of live bacteria, such as Lactobacillus bulgaricus and Streptococcus thermophilus, in the form of yogurt was beneficial for gastrointestinal health, as well as for health in general, and for longevity. Some recent research suggests that certain live microorganisms may have immunomodulatory and anticarcinogenic effects, as well as other health benefits. There is presently much active research focusing on the development of target-specific probiotics containing well-characterized bacteria that are selected for their health-enhancing characteristics. These new probiotics are entering the marketplace in the form of nutritional supplements and functional foods, such as yogurt functional food products.

The gastrointestinal tract represents a complex ecosystem in which a delicate balance exists between the intestinal microflora and the host. The microflora are principally comprised of facultative anaerobes and obligate anaerobes. Approximately 95% of the intestinal bacterial population in humans is comprised of obligate anaerobes, including Bifidobacterium, Clostridium, Eubacterium, Fusobacterium, Peptococcus, Peptostreptococcus and Bacteroides. Approximately 1% to 10% of the intestinal population is comprised of facultative anaerobes, including Lactobacillus, Escherichia coli, Klebsiella, Streptococcus, Staphylococcus and Bacillus. Aerobic organisms are not present in the intestinal tract of healthy individuals with the exception of Pseudomonas, which is present in very small amounts. Most of the bacteria are present in the colon where the bacterial concentration ranges between 1011 to 1012 colony-forming units (CPU) per milliliter.

The intestinal microflora are important for maturation of the immune system, the development of normal intestinal morphology and in order to maintain a chronic and immunologically balanced inflammatory response. The microflora reinforce the barrier function of the intestinal mucosa, helping in the prevention of the attachment of pathogenic microorganisms and the entry of allergens. Some members of the microflora may contribute to the body's requirements for certain vitamins, including biotin, pantothenic acid and vitamin B12. Alteration of the microbial flora of the intestine, such as may occur with antibiotic use, disease and aging, can negatively affect its beneficial role.

The probiotics that are marketed as nutritional supplements and in functional foods, such as yogurts, are principally the Bifidobacterium species and the Lactobacillus species. Probiotics are sometimes called colonic foods. Most of the presently available probiotics are bacteria. Saccharomyces boulardii is an example of a probiotic yeast.

The following describe the various bacteria and yeasts used as probiotics:

BIFIDOBACTERIUM

LACTOBACILLUS

LACTOCOCCUS

SACCHAROMYCES

STREPTOCOCCUS THERMOPHILUS

ENTEROCOCCUS

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