One old adage says that we have to eat a peck of dirt for better immunity. It means that exposure to a little dirt and few harmless microorganisms is beneficial to health. Recent studies have suggested that lack of contact with bacteria in early life is partially responsible for a less robust immune system. This is corroborated with the hygiene hypothesis by Strachan in 1989, linking increased incidence of atopic disorders to modern hygienic life style (use of detergents and antibacterials) in rich countries.
The body is full of bacteria, in and on the skin, mouth, upper respiratory tract, urogenital tract and in the gut. There are ten times more bacteria than human cells in our bodies. We are more microbe than human. The gut (upper GI tract, ileum and colon) microflora constitutes a large biomass of 1010 to 1012 per gm content, with close to 500 different species. In this world we are not alone. Billions of bugs live within us and they are crucial to good health. Friendly bacteria are vital to proper development of the immune system, protection against pathogenic microorganisms and to the digestion and absorption of food and nutrients. Before a baby is born, the intestinal tract is sterile. We start accumulating our resident microbes during the birth process. During vaginal birth, the neonate is colonized by the mother’s vaginal and fecal bacteria. Colonization is delayed in infants born via caesarean section. Similarly formula-fed infants have not demonstrated the same succession of microorganisms as seen in their breast-fed counterparts. The microbiota dominated by bifidobacteria is beneficial to health (Probiotics in the pediatric practice
www.everidis.com).
WHO and FAO of United Nations defined Probiotics as the live microorganisms, which when administered in adequate amounts, confer a health benefit on the host. They are similar to beneficial microorganisms found in the human gut and are called friendly bacteria and good bacteria. Evidence is mounting that an early and intimate interaction between gut microbes and host defense mechanisms are key to the maintenance of a balance between tolerance of innocent exposures and ability to mount an inflammatory response. Probiotics are available to consumers mainly in the form of dietary supplements. Prebiotics are non-digestible and non-absorbable food ingredients in upper GI tract such as oligosaccharides, dietary fibres, proteins etc. that selectively stimulate the growth and / or activity of beneficial organisms already in people’s colons. When Probiotics and Prebiotics are mixed together, they form symbiotic.
Probiotics are available in foods such as yogurt, fermented and unfermented milk, Japanese meso, Tempeh, some cheeses, soy beverages, bananas, garlic and onions which can also help repopulate levels of good bacteria in the intestine. Medical antibiotics, drinking of alcoholic beverages, birth control pills and many allopathic drugs contribute to destruction of the intestinal flora.
Gut microbiota produce antimicrobial peptides and molecules, which have the effect of killing enteric pathogens and inhibiting pathogen – host cell interactions. There is a normal dynamic balance between good and bad bacterial population in the gut. When this is disturbed by intake of chemicals, antibiotics etc. which result in eco-imbalance i.e. replacement of beneficial micro-flora by pathogenic bacteria like clostridia causing disease. Recent evidence supports that disturbances in the bacterial microbiota result in dysregulation of adaptive immune cells and this may underlie disorders such as inflammatory bowel disease eg. ulcerative colitis (Nature Reviews/Immunology, May 2009;313). Probiotics are useful in treating diarrhoea, infections of the urinary tract or female genital tract, irritable bowel syndrome and in management of atopic dermatitis (eczema) in children (www.nccam.nih.gov/health/probiotics/).
Most frequently studied probiotic species are the lactobacilli and bifidobacteria. A good probiotic supplement will contain millions of live bacteria to bolster and replenish levels of health promoting good bugs in our digestive tract. These will improve the digestion and absorption of food and stimulate and support the immune system (www.healingdaily.com/probiotics.htm). Probiotic products are taken by mouth as dietary supplements and are manufactured and regulated as foods, not drugs. Americans’ spending on probiotic supplements, for example, nearly tripled from 1994 to 2003. Intake of natural foods having probiotics is advised by nutritionists, compared to dietary probiotic supplements in the form of capsules, tablets and powders.
December 17, 2009 Prof. B. C. Harinath
