Whether you are an elite and professional athlete, a recreational athlete or a novice trainer, improved athletic performance would be a key focus for you and this includes faster recovery from physical fatigue and achieving over-all wellbeing. Growing scientific evidence suggest that optimum gut health and efficiently functioning immune system are key for achieving high performance (Jäger et al., 2019). The emerging scientific evidence suggest that one of the key contributors to improving gut health, immune function and post training recovery, leading to enhanced performance are gut probiotics, the healthy gut microorganisms (Jäger et al., 2019 & 2016; Maughan et al., 2018; Wakeman, 2013).
According to the World Health Organisation (WHO) and the International Olympic Committee (IOC), probiotics are healthy live micro-organisms (mainly bacteria) that when administered orally in adequate amount for several days/weeks can increase the numbers of beneficial bacteria in the gut and confer several health benefits to the host (a person). These bacteria can live in the gut and in some fermented, raw and living foods. The concept of probiotics is not new; around 1900 Nobel laureate, Elie Metchnikoff, discovered that the consumption of live bacteria (example: L. bulgaricus) in yogurt or fermented milk improved some biological features of the gastrointestinal (GI) tract. Probiotics have been associated with a range of potential benefits to gut health, modulation of immune function and wellness and their benefits are especially important for endurance and/or recreational athletes (Jäger et al., 2019; Maughan et al., 2018; Wakeman, 2013). Bacteria with claimed probiotic properties are now widely available in the form of foods such as dairy products and juices, and also as capsules, drops, and powders. Scientists categorise microorganisms with genus, species and strain names. For example, for the probiotic bacterium, Lactobacillus rhamnosus GG, the genus is Lactobacillus, the species is rhamnosus and the strain is GG.
Benefits of probiotics depend on the combination of various strains and doses. Commercially, probiotics can be available as a single bacterium or a cocktail of multiple stains.
A recent review published in 2019 in the Journal of International Society of Sports Nutrition reviewed 299 studies in this field. According to this review and several emerging evidence, the probiotics functions can be discussed in the following categories:
GI problems often occur in endurance athletes during prolonged events (such as cycling, triathlons and marathons), especially in challenging conditions. Symptoms may include nausea, cramping, bloating and diarrhoea. Recent research indicates that probiotic supplementation, using certain combination of probiotics strains, can promote improvements in exercise performance through various pathways in athletes and physically active individuals. A few recent studies (Vaisberg et al., 2019; Salarki et al., 2013) have demonstrated that multi-strain probiotics supplementation, a few weeks’ pre-race, lowered GI symptoms significantly and improved immune and inflammatory functions in marathon runners. A number of studies have demonstrated that multi-strain probiotics supplements in endurance trainers and resistance trained men increased their VOmax, aerobic power, training performance and improved range of motion during acute recovery. These studies also found decrease in inflammation (cytokines) and reduction in incidence of Upper Respiratory Tract infections in athletes taking probiotics supplements (Huang et al., 2019; Gapner et al., 2017; Jäger et al., 2016; Salehzadeh 2015; Salakia et al., 2013)
So let’s see how probiotics achieve the above mentioned beneficial effects?
Role of probiotics in post-training recovery of fatigued muscles and systems
Fatigued and/or damaged muscles, systemic inflammation and build-up of harmful and muscle damaging oxidative molecules (called oxidative stress) are common in athletes and these can impact post-training recovery and performance. As discussed above, supplementation of selected anti-inflammatory probiotic strains has been linked to improved recovery from muscle-damaging exercise by removing inflammatory molecules, reducing oxidative stress and improving the availability of essential amino acids and vitamins. Specific strains of probiotics can prevent frequent episodes of respiratory infections. These are crucial in healing of damaged muscles and post-training recovery (Huang et al., 2019; Gapner et al., 2017; Jäger et al., 2016; Salehzadeh 2015; Salakia et al., 2013).Maintaining hydration
Probiotics have been demonstrated to maintain ion transporters in the gut lining, helping maintaining optimum cellular hydration and preventing gastric upset (Jäger et al., 2019).
Modulating neurotransmitters, hormones and stress
Preclinical and early human research has shown that probiotics have potential benefits relevant to an athletic population. These include improved hormonal functions related to body composition and lean body mass, normalizing age-related declines in some hormones (example: testosterone levels), reductions in stress hormone (cortisol) levels, improved responses to a physical or mental stressor, reduction of exercise-induced lactate, and increased neurotransmitter synthesis (related to cognition and mood). However, these potential benefits require validation in more rigorous human studies and in a diverse athletic population (Jäger et al., 2019).
The main benefit for elite or high performing athletes is expected to be in achieving the faster post-training recovery, reduced incidents of infections and over-all wellbeing. These athletes may already be performing to their optimum levels and hence may not notice the changes in their performance as a result of probiotic supplements (Jäger et al., 2019).Novice trainers
Novice trainers taking regular probiotics supplements are expected to notice differences in their performance, post-training recovery and over-all well-being (Jäger et al., 2019).
The endurance training and physical activities put additional demand on the physiological and immunological processes. Probiotics alone are not sufficient to achieve your overall fitness and performance goals. Research evidence suggest that balanced diet of healthy protein (example whey protein, salmon fish), fibre, carbohydrates and some forms fatty acids enhance the functions of probiotics. Some food types which promote probiotic functions are called prebiotics, examples include fermented food (examples: yogurt, whey, buttermilk, pickles, fermented soybean food, kimchi), garlic, onions, oats, barley, cocoa, flaxseed, banana, apple, greens and salmon fish. In addition, the physical activity has been shown to positively promote probiotics growth and functions (Jäger et al., 2019).
Common probiotic species in commercial use are mainly derived from fermented foods with a long history of human consumption. These are considered safe for the general population by the European Food Safety Authority (EFSA, Jäger et al., 2019). People with specific medical conditions should seek medical advice.
Considering the growing scientific evidence related to benefits and favourable safety profile of probiotic supplementation reported in sports and medical journals, probiotics are generally used to optimize the performance, recovery and over-all health of athletes. Regular consumption of specific probiotic strains especially a product with multi-strain combination, may improve immune functions, reduce the number of respiratory infections and GI discomfort an athlete may experience during endurance training in challenging conditions. In addition, probiotics improves gut integrity and hence improve nutrient absorption, reduce allergies and improve post-training recovery ad performance. The benefits of probiotics are specific to strains when consumed at adequate doses. It is therefore important that athletes must choose the product with clinically researched strains with health validated benefits and products should be clean from any banned substances.