What is Prebiotics and Probiotics?
Probiotics are defined as "microbial preparations or components of microbial cells that have a beneficial effect on health and well being"⁽¹⁾. Various bacterial genera most commonly used in probiotic preparations are Lactobacillus, Bifidobacterium, Escherichia, Enterococcus, Bacillus and Streptococcus. Some fungal strains belonging to saccharomyces have also been used.^(2-4)

Prebiotic is a non-digestible food ingredient that confers benefit on the host by selectively stimulating the growth and/or activity of one bacterium or a group of bacteria in the colon, and thus improve the host health. Prebiotics are dietary carbohydrates that escape digestion in the upper gastrointestinal tract, alter the bacterial composition of the gut, by changing the type of the substrate provided to the existing microbial population in the gut. Common prebiotics are fructo-oligosaccharides, gluco-oligosaccharides and inulin. Both probiotics and prebiotics together called as synbiotics improve the survival of the bacteria in the GIT so that their effect is more.^(3,5)

Effect of probiotics on health: Several mechanisms have been postulated regarding action of probiotics. Probiotic bacteria especially lactobacillus has proven beneficial effects on intestinal immunity. It increases the number of IgA and other immunoglobulin secreting cells in the intestinal mucosa, stimulates local release of interferons and facilitates antigen transport to underlying lymphoid cells, which serves to increase antigen uptake in Peyer's patches.⁽⁶⁾ Partial lactose digestion and stimulation of the intestinal mucosal lactase activity has been postulated as a possible mechanism against some types of diarrhea.⁽⁵⁾ Probiotics prevent colonization of pathogens by competitive inhibition.⁽⁷⁾ The other suggested mechanisms are lowering intestinal pH, release of gut protective metabolites, regulation of intestinal motility and mucus production.⁽⁵⁾ At adequate daily feeding levels, lactobacillus acidophilus NCFM, a probiotic strain available in conventional foods (milk, yogurt and dietary supplements) may facilitate lactose digestion in lactose intolerant subjects.⁽⁸⁾

Clinical uses of probiotics: Randomized double-blind studies have provided evidence of probiotic effectiveness for the treatment and prevention of acute diarrhea and antibiotic-induced diarrhea, as well as for the prevention of cow milk-induced food allergy in infants and young children^(9-11). There are also studies indicating that probiotics may be useful for prevention of respiratory infections in children, dental caries, irritable bowel syndrome and inflammatory bowel disease and urinary tract infections^(12-16). Studies have reported modification of allergic reactions for atopic eczema when supplemented with probiotics especially Lactobacillus GG⁽¹⁷⁾.

Necrotizing enterocolitis (NEC) occurs more in low birth weight preterm children. It is found that stools of these infants contains less lactobacillus and bifidobacterium than the controls⁽⁵⁾ and trial with probiotic supplementation resulted in 60% reduction in NEC and overall mortality in 1237 newborns in Columbia⁽¹⁸⁾.

Probiotics have an in vitro inhibitory effect, reduced H.pylori associated gastric inflammation in animals, improved H.pylori associated gastritis and also probiotic treatment reduced H. pylori therapy associated side effects.⁽¹⁹⁾

Use of probiotics in healthy children: Consumption of probiotics presents a negligible risk to consumers⁽²⁰⁾ though there have been cases of sepsis secondary to Lactobacillus rhamnosus GG reported⁽²¹⁾ especially when the organism is enterococcus and patient is immunocompromised. However study in healthy preschoolers and children taking 6 months of probiotic have found to reduce fever incidence by 53% - 72.7%, coughing incidence by 41.4% - 62.1% and rhinorrhea by 58.8% and lead to reduction in days absent from group child care by 27.7% - 31.8% suggesting that long term probiotic supplementation was safe and effective way to reduce fever, rhinorrhea, cough and number of missed school days in these children⁽²²⁾.

Conclusion: Data suggests that probiotics may promote good health in day care and work settings and may decrease incidence of infections in healthy as well as ill children. Long term consumption of probiotics appears to be safe.

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