What are probiotics?

Probiotics are species of health-promoting bacteria that we require for proper digestion of food and immune defense against illness promoting bacteria, viruses, and fungi. The term "probiotic" derives from Latin and Greek, meaning "for life". The World Health Organization (WHO) has defined probiotics as "live micro-organisms which when administered in adequate amounts confer a health benefit on the host".1 To put this simply, probiotics, which are also known as "intestinal microflora", are "good bacteria" that live in our gastro-intestinal (GI) tract and aid in promoting optimal health and preventing illness. Although these bacteria live throughout our intestinal tract, they are found in the highest concentrations at the far end of the small intestine and in the large intestine.2

Research has demonstrated that the total number of bacteria living in a healthy adult amounts to ten times more bacteria than the total number of cells in the human body!3 In fact a healthy intestinal tract should contain up to 1 kg (over two pounds) of bacteria.4 Most of these organisms are either neutral or health promoting but some have the potential to cause illness (e.g. Salmonella or E. Coli). In order to be healthy and to prevent the colonization of harmful bacteria, our GI tracts must contain sufficient numbers of the health promoting beneficial bacteria.


1. Reid, G., Jass J., Sebulsky M.T., and McCormick J.K. 2003. Potential Uses of Probiotics in Clinical Practice. Clinical Microbiology Reviews. 16(4):658-672.

2. Caicedo R.A., Schanler R.J., Li N., and Neu J. 2005. The Developing Intestinal Ecosystem: Implications for the Neonate. Pediatric Research. 58(4): 625-628.

3. Gill H.S. and Guarner F. 2004. Probiotics and human health: a clinical perspective. Postgraduate Medical Journal. 80:516-526.

4. Bengmark, S. M.D. Ph.D. 1998. Immunonutrition: Role of biosurfactants, fiber, and probiotic bacteria. Nutrition. 14:585-594.