The term probiotics are derived from the Greek word means “for life”. It was first observed by Lilly and Stillwell in 1965. Currently, WHO and FAO defined probiotics as “live microorganisms which when administered in adequate amounts confer a health benefit to the host”. Lactic acid bacteria (LAB) and Bifidobacteria are the most common types of microbes used as probiotics but certain yeasts and bacilli may also be used. They are microbial organisms and remain viable and stable after culture manipulation, and storage before consumption. They survive gastric and pancreatic digestion and can adhere to the mucosal surface. Able to induce host response once they enter the intestinal microbial ecosystem and they yield functional and clinical benefits to the host when consumed and they should be colonized. They should colonize the intestine and can utilize the passage through the digestive system. They are nonpathogenic and non-toxic. These are capable of exerting a beneficial effect on the host.
Mechanism of Action of Probiotics
- Although not well documented, some mechanisms probiotic action includes.
- Competition for adhesion sites with pathogens in which: Adhere to the epithelium and act “colonization barriers” by preventing the pathogen from adhering to the mucosa.
- Synthesis of antimicrobial compounds: Produce bacteriocin and other antimicrobial compounds such as hydrogen peroxide, diacetyl, and short-chain fatty acids.
- Stimulate the immune response: Increase the secretion of IgA, enhance the phagocytic activity of macrophages, enhance lymphocyte cytokines response.
- Probiotics may also compete for nutrients that would otherwise be utilized by pathogens: Probiotics utilize the monosaccharides, which results in the inhibition of Clostridium difficile.
- Promote excretion of toxic substances such as bile acids, nitrosamines, and mutagenic compounds. Commercial Forms of Probiotics: There are two main forms in which probiotic organisms can be ingested
- Fermented food: dairy e.g. yogurt and vegetable origin e.g. Sauer kraut
Firstly observed by Gibson and Roberfroid, who define prebiotic as “a non-digestible food ingredient that confers beneficial effects in the host by selectively stimulating the growth or activity of one or a limited number of bacteria in the colon and thus improves host health and well-being”. Prebiotics are essentially fiber from plants (fruits, vegetables, or whole grains). Prebiotics transit through the stomach and small intestines undigested. They make their way to intact to the colon, where they will be bacterially fermented together with the unabsorbed nutrients. Lactobacilli and Bifidobacterium more likely to benefit from prebiotics
Examples of Prebiotics
- Fructo oligosaccharides (such as insulin and its derivatives).
- Other oligosaccharides such as raffinose, stachyose, and verbascose.
- Polysaccharides(such as cellulose, hemicellulose, and pectin)
- Soybeans oligosaccharides etc.
Benefits of Prebiotics
- Reduce blood glucose
- Increment of high-density lipoprotein (HDL)-cholesterol level.
- Reducing energy intake (which results in weight management especially in combination with probiotics.
- Having positive effects on the immune system (e.g. less risk for allergy in both infants and adults especially in combination with probiotics).
- Enhancing the feeling of satiety.
- Providing energy-yielding metabolites through colonic fermentation.
- Improving regularity by increasing stool bulk.
Probiotics in prevention and treatment
- Probiotics have a wide range of beneficial effects and numerous indications.
- Acute diarrhea
- Antibiotic-associated diarrhea
- Allergy prevention
- Probiotics reduce 57% diarrheal diseases especially acute infectious diarrhea.
- Antibiotic-associated diarrhea is an acute inflammation of the intestine mucosa by the administration of a broad spectrum of antibiotics.
- Several probiotic bacteria reduce risk from 28.5% to 11.9%.
- Nosocomial diarrhea is reduced by B.bifidum and S.thermophillus