Prebiotics and Probiotics; A Synopsis

The concept of orally taking mixtures of microorganisms for improved haelth is not new. Yogurt and other fermented foods have long been thought to
have health benefits.The Lactic acid bacilli in the fermented food are responsible for these benefits.Recently there is an emerging interest in the use of various 'living microbials' in many clinical situations.

To understand the concept of probiotics and prebiotics a brief review of the normal GI flora and its immune effect is necessary.The GI biomass is a metabolically active organ of host defence.Approximately 500 different microbial species colonise the human GI tract,the maximum concentration being in the colon. The organisms which predominate are Bacteroides, Lactobacilli, Clostridium, Fusobacterium, Bifidobacterium, Peptococci, Escherichia and Vellionelli. They play a crucial role in host nutrition, physiology and control of immune system. Various stresses both physiological and
pathological lead to alteration in the microflora which can affect the host adversely.

Probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host(WHO 2002).The most widely used probiotics are Lactobacilli sp., Bifidobacteriae sp. and Saccharomyces boulardii an yeast. When administed in adequate doses they inhibit the pathogenic bacteria, reinforce the gut barrier, promote secretion of friendly cytokines and augment the immune system.

Prebiotics are complex carbohydrates. They reach the colon undigested as humans lack the enzymes to digest them.The colonic bacteria ferment these agents and produce short chain fatty acids which act as the main source of energy for probiotics and colonocytes.

A judicious combination of probiotic and perbiotic is called a synbiotic.

These 'living drugs'are found to be beneficial in many disorders. The strongest evidence is for their role in acute diarrhoeal diseases and prevention and treatment of antibiotic associated diarrhoea.Research has shown lot of promise in situations  like prevention of infection in acute pancreatitis and post operative states, inflammatory bowel disease, pouchits, radiation colitis, allergic diseases and prevention of cancer. Data is inadequate to support their use in irritable bowel syndrome.

Various preparations with different combinations of prebiotics and probiotics in various concentrations are currently available.The dose recommended is one to two capsules per day. These agents are generally safe and well tolerated

The use of probiotics and prebiotics as therapeutic agents for various disorders is rapidly moving into mainstream.Mechanisms of action explain the
therapeutic effects and randomised controlled trials provise necessary evidence for their incorporation into the therapeutic armamentarium.