What is it?
- Probiotics are live microbial food supplements that may have beneficial effects on intestinal microbial balance and associated impact on health. The two main species used in commercial preparations are lactobacillus acidophilus and bifidobacterium bifidum.
- Microbes have been used for many years in food preparation – for example, the manufacture of yoghurt and cultured dairy foods, kombucha and alcoholic fermentations. In recent years, a number of different probiotic formulations and supplements have been scrutinised in scientific research (primarily in infants) to examine their impact in modulating gut bacteria or microbiota. The gut microbiota performs several vital functions, including regulating mucosal immune activity, modulating host metabolic activity and protecting against intestinal infection. Dietary manipulation may enhance gut bacteria composition and metabolic activity and promote optimum immune function.
- Dietary modification, and in particular increasing grain or fibre intake, should be recognised as the primary factor in enhancing gut microbiota diversity, and this can occur within a few days of dietary manipulation. Only after this has been optimised, should consideration be given to probiotic supplementation.
- Beneficial effects of enhancing the gut microbiota diversity may include improved intestinal tract health, enhanced immune system1, greater bioavailability of nutrients, reduced lactose intolerance, lower prevalence of allergy in susceptible individuals, and improved mental health.2
- Apart from gut and respiratory health3, the purported benefits of enhancing gut microbiota diversity in a sporting context include improved body composition and lean body mass, reduction in stress hormones such as cortisol, attenuating age-related declines in testosterone levels, and increased concentration of neurotransmitters that might enhance cognition and mood.4
- The mechanisms of action of probiotic supplementation are largely unknown, but may involve altering the makeup of gut microbiome, modifying gut pH (acidity), producing antimicrobial compounds, modulating gut permeability, stimulating immunomodulatory cells, preventing pathogen infection through ‘competitive exclusion’, or limiting the GI tract surface area available for colonisation.5
- Issues with dosage, viability of probiotic strains, lack of industry standardisation and potential safety issues, are being further investigated in the food additives industry and research studies. Applications of probiotics in sports nutrition and medicine are still emerging.6
- Although most studies in active individuals and athletes report positive effects on health, there is little evidence showing improvements in sporting performance. The general consensus is that probiotics may confer small variable benefits in performance and recovery, but further laboratory, clinical and field-based studies are required to provide definitive guidelines for athletes.