Supplement Overview

• Probiotics are live microbial food supplements that have beneficial effects on health and in particular intestinal microbial balance. The two main commercially used species are lactobacillus acidophilis and bifidobacterium bifidum.
• Microbes have been used for many years in food and alcoholic fermentations and in recent years have been scrutinised in scientific research to examine their purported health benefits.
• There is evidence of the following beneficial effects of probiotics: improving intestinal tract health, enhancing the immune system, enhancing the bioavailability of nutrients, reducing lactose intolerance, decreasing the prevalence of allergy in susceptible individuals, and reducing the risk of certain types of cancers.
• Mechanisms of action are largely unknown, but may involve modifying gut pH (acidity), producing antimicrobial compounds, and stimulating immunomodulatory cells.
• Probiotics can be obtained from foods, primarily dairy products (e.g. yoghurt and milk) and commercial supplements. Foods are a better choice due to the synergistic effects between food compounds and probiotic cultures.
• Most studies report effective dosages of 109-1010 organisms per day (i.e. 1-10 billion bacteria). This concentration corresponds to about one litre of acidophilus milk (formulated at 2 x 106 cfu/ml). Studies at the AIS show that almost all athletes will safely tolerate dosages of 2 billion bacteria per day. Lower levels may benefit some individuals. Daily consumption is recommended as probiotics will pass through the intestine.
• Shelf-life of most probiotic products is about 3-6 weeks when kept at 40C. Shelf-life of dried supplements is about 12 months, but levels of probiotics may drop significantly over this time. The concentration of bacteria in food products varies enormously and some research indicates that commercially available products contain no live bacteria.
• Problems with dosage, viability of probiotic strains, lack of industry standardisation and potential safety issues, are being addressed in research studies. Applications of probiotics in sports nutrition and medicine are still emerging.
• The AIS conducted a study on lactobacillus fermentum in highly trained distance runners in 2003. A highly significant favourable reduction in the number of symptoms days was observed in the probiotic group compared with placebo treatment, although the underlying immunological control mechanisms were not clearly established.
• A collaborative study between the AIS and the university of Newcastle published in 2006 (British Journal of Sports Medicine 40(4):351-354) indicated that fatigued athletes with lowered immune responses may benefit from probiotic supplementation.
• A follow-up probiotic supplementation study conducted at the AIS with distance runners in 2006 was unable to demonstrate a substantial positive effect of supplementation on immune function, the incidence of illness, or exercise performance.
• Probiotic supplementation appears beneficial for fatigued athletes with an identifiable immune deficiency, but its efficacy for healthy well performing athletes remains to be established.

Concerns Associated with Supplement Use

• Occasional reports of bacteraemias and endocarditis in severely immunocompromised individuals.
• Epidemiological studies report no evidence of probiotics being involved with infections.
• Individuals with a prior history of gastrointestinal tract problems such as coeliac disease or irritable bowel syndrome may be a greater risk of known side effects such as an upset stomach or bowel problems.
• Current recommendations suggest that well-known probiotic species should be introduced gradually into the diet, building up to the recommended daily levels over a period of two to three weeks.

Last Updated 3/1/07

This fact sheet has been prepared by the AIS Sports Nutrition as part of the AIS Sports Supplement Program. The AIS Sports Supplement Program has been designed for the specific needs of AIS athletes. It is recommended that other athletes and groups seek independent advice before using any supplement. © Australian Sports Commission 2007