A to Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance - part 31 GleesonMichael SieglerJ.C. BurkeL.M. StearS.J. CastellL.M. 2012 This issue deals with the increasingly interesting topic of probiotics and also, slightly out of alphabetical order, with pycnogenol, a product usually associated with pine bark. Probiotics are food supplements containing live microorganisms. They modify intestinal microbiota in a way that enables beneficial bacteria to increase. An additional benefit is that probiotics in sufficient quantities also tend to decrease those species of bacteria which are considered harmful. It is suggested that this situation produces many potential benefits for the health and functioning of the digestive system, and also has a beneficial effect on immune function. In the short review below, the effects of probiotics and their efficacy in reducing infection incidence (or symptom severity/duration) in athletes are summarised. Pycnogenol supplementation has previously been considered to have a range of beneficial effects, including antioxidant and anti-inflammatory properties.