Health Benefits of Probiotics in Sport and Exercise - Non-existent or a Matter of Heterogeneity? A Systematic Review

Abstract

BackgroundThe use of probiotics in sports has been growing in recent years, as up to 50% of athletes suffer from training- and performance-limiting gastrointestinal (GI) problems. Moreover, repeated exhaustive exercise and high training loads may lead to a transiently depressed immune function, associated with an increased risk of upper respiratory tract infection (URTI).AimTo provide a qualitative analysis of probiotic effects on URTI, GI symptoms and the immune system in healthy individuals under consideration of performance level as main classifier.MethodsA systematic review of the literature was conducted (PubMed, SPORTDiscus with Full Text, Web of Science) to analyze the effects of probiotics in athletes and healthy active individuals on GI problems, URTI, and the immune system. A qualitative synthesis with performance level and treatment duration as main classifiers was performed.ResultsOf 41 eligible studies, 24 evaluated the effects of probiotic supplements in athletes, 10 in recreationally active individuals and 7 in healthy untrained adults. Large heterogeneity was observed in terms of probiotic strains, mode of delivery, performance level, treatment duration and outcome assessment. Overall, studies provided inconsistent observations.ConclusionThe effects of probiotics on immune system, URTI, and GI symptoms in athletes, healthy adults and recreationally active individuals remain inconclusive. Based on the analyzed studies and identified parameters, this article provides suggestions to align future research on the effects of probiotics in exercise.Systematic Review RegistrationPROSPERO, identifier: CRD42021245840.

Change in the Gut Microbiome and Immunity by Lacticaseibacillusrhamnosus Probio-M9

“…However, an active debate has been going on for years about whether the consumption of probiotics is beneficial for nonpatients in quality-of-life improvement and disease prevention ( 27 – 29 ). Although previous studies supported a beneficial effect of probiotics in enhancing immunity against the common cold, which can reduce the incidence ( 30 ), duration ( 31 ), and symptoms ( 32 ) of the common cold ( 28 , 33 , 34 ), some reported that the effects of the probiotics on the immune system and gastrointestinal symptoms in nonpatients are limited ( 29 , 35 ).…”

“…However, an active debate has been going on for years about whether the consumption of probiotics is beneficial for nonpatients in quality-of-life improvement and disease prevention ( 27 – 29 ). Although previous studies supported a beneficial effect of probiotics in enhancing immunity against the common cold, which can reduce the incidence ( 30 ), duration ( 31 ), and symptoms ( 32 ) of the common cold ( 28 , 33 , 34 ), some reported that the effects of the probiotics on the immune system and gastrointestinal symptoms in nonpatients are limited ( 29 , 35 ). One approach by which probiotics impact the host immune system is through the microbial metabolism that arises from intestinal microbiota catabolism ( 36 – 39 ): e.g., functional metagenomic studies have identified the associations between host proinflammatory cytokines and microbial tryptophan and palmitoleic acid metabolic pathways ( 37 , 38 , 40 – 42 ).…”

Prebiotic properties of isomaltooligosaccharides from cassava as a potential ingredient in high-protein drinks for athletes

“…These benefits included the impact of probiotics on oxidative stress, inflammatory response, sports performance, immune-system function, and upper respiratory tract infection (URTI) [28]. An imbalance in gut microbiota may limit the training performance of athletes, leading to poor competitiveness, a decline in overall well-being, fatigue [29], depression, and anxiety [30]. Therefore, problems with a high prevalence of upper respiratory (URTI) and gastrointestinal (GI) tract infections are welldocumented and pertain to increased permeability of the gastro-intestinal epithelial wall, mucous thickness disruption, and subsequent higher rates of bacterial translocation [31].…”

“…As the blood supply to the GI tract decreases by 60 to 70% at exercise intensities of 70% of maximum oxygen consumption (VO2max), this decrease in blood supply may also reduce mesenteric blood flow [30]. Increasing evidence supports the idea that maintaining a healthy balance of beneficial bacteria in the microbiome can support immunity, leading to fewer illnesses and sustaining optimal health.…”

Effect of prebiotics, probiotics, and synbiotics on gastrointestinal outcomes in healthy adults and active adults at rest and in response to exercise—A systematic literature review

“…Recently published narrative or opinion piece reviews exploring prebiotics (i.e., non-digestible material that can be fermented by bacteria in the lower gastrointestinal tract), probiotics (i.e., live bacteria which survive transit to colonize the lower gastrointestinal tract), and synbiotics (a combination of pre-and pro-biotics) in active adults, have implied a beneficial effect on the gastrointestinal tract in response to exercise and improved performance; however the primary focus has been on exercise performance or immunological outcomes (22)(23)(24)(25)(26)(27)(28)(29). Unlike these narrative or opinion-based reviews, recent systematic literature reviews (SLR) that focused and/or included pro-and/or synbiotic supplementation, concluded inconsistent methodologies and/or findings that provided no convincing evidence of any substantial beneficial effects resulting from probiotic supplementation in healthy populations (30)(31)(32). Although it is important to note that these SLR did not comprehensively evaluate EIGS markers or changes to fecal bacterial taxa or SCFA.…”