Probiotics or Prebiotics?

With the rising interest in nutrition, the idea of using supplements in addition to usual food is also becoming more popular. Some of the most famous such additions are pro - and prebiotics, yet many people tend to confuse the two. They might sound similar, but the action mechanisms and hence the effects they have on the body are different.

“Probiotics” translated from Greek means “prolife”[1], and rightfully so, since these are actual living microorganisms, most commonly - bacteria and yeast. Another important part of the definition are health benefits. As stated by the WHO probiotics are “Live microorganisms which when administered in adequate amounts confer a health benefit on the host”[2].

Conversely, “prebiotics” are defined as “nondigestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon, thus improving host health”[3]. In other words, these consist of fiber indigestible for humans, but which can be fermented by bacteria. In a way, prebiotics are the food for probiotics.

There is some strong evidence of beneficial effects of probiotics on such conditions as inflammatory bowel disease (IBD), antibiotic associated diarrhoea (AAD) and acute gastro-enteritis caused by rotavirus, along with some associations with improvements for immunity and allergic diseases[4]. Probiotics can often be found in fermented products, such as yoghurt, kefir and pickles.

Prebiotics have been shown to facilitate the growth of certain types of beneficial bacteria, in particular - bifidobacteria and lactobacilli. Some of the species belonging to those groups are able to produce broad - spectrum antibiotics. Therefore, prebiotics might play a role in resistance to pathogens[5]. Since fiber consists of carbohydrates, some of the foods that exhibit prebiotic effects are bananas, whole grain wheat and whole grain corn[6].

It is necessary to note that nutrition is a rather new path for research and many proposed health effects still require further investigation.


Milad Rouf Final Year Medical Student, Cardiff University.

1. Lee, Y.K. and Salminen, S., 2009. Handbook of probiotics and prebiotics. John Wiley & Sons.

2. Joint, F.A.O., 2002. WHO working group report on drafting guidelines for the evaluation of probiotics in food. London, Ontario, Canada, 30.

3. Roberfroid, M., 2007. Prebiotics: the concept revisited. The Journal of nutrition, 137(3), pp.830S-837S.

4. Ouwehand, A.C., Salminen, S. and Isolauri, E., 2002. Probiotics: an overview of beneficial effects. In Lactic acid bacteria: genetics, metabolism and applications (pp. 279-289). Springer, Dordrecht.

5. Gibson, G.R., 1999. Dietary modulation of the human gut microflora using the prebiotics oligofructose and inulin. The Journal of nutrition, 129(7), pp.1438S-1441S.

6. Slavin, J., 2013. Fiber and prebiotics: mechanisms and health benefits. Nutrients, 5(4), pp.1417-1435.