Probiotics: Sources, selection and health benefits

Probiotics are defined as "live microorganisms that, when administered in adequate amounts, confer a health benefit on the host". Nowadays, the probiotic market is growing tremendously by using probiotics especially in foods, dietary supplements and pharmaceutical applications. Sometimes, the consumers get confused between probiotics and non-probiotics. A more precise use of the term "probiotics" will be useful to guide consumers and other stakeholders in differentiating the diverse products on the market. Since efficacy of probiotics is strain specific, the appropriate selection of probiotics is extremely important. This review focuses on discussing the following issues of probiotics including their major sources, selection criteria, health benefits and possible harms. The main selection criteria for probiotics include the following ability to: tolerate into a product at a sufficient level and remain viable throughout the shelf life of the product; withstand transit through a gastrointestinal tract; adhere to intestinal epithelial cells and colonize the lumen of the tract; produce antimicrobial substances against the pathogens and to be harmless to a host associated with the health benefits. The major health benefits of probiotics involve an improvement of intestinal health, an enhancement of the immune response, a prevention/treatment of infectious disease and a prevention/treatment of cancer.