Effect of prebiotics, probiotics and symbiotics on gut microbiota in sedentary subjects and athletes: narrative review

The gut microbiota, a complex community of microorganisms, and its impact on health is a topic of mounting interest in the scientific world. Recent studies have highlighted its importance in regulating fundamental physiological functions, and emphasize how proper microbial balance (eubiosis) is associated with a healthy state, while an alteration in this balance (dysbiosis) is related to metabolic and inflammatory disorders. Physical activity and a healthy, balanced diet promote proper modulation of the microbiota; but inactive and unhealthy lifestyles make clear the need to support the body through supplementation of probiotics, prebiotics and symbiotics. Indeed, prebiotics, nondigestible fiber, and probiotics, beneficial live microorganisms, improve the diversity of the microbiota, inducing proper eubiosis. The aim of this narrative review was to investigate the effect of prebiotics and probiotics in two particular categories of people whose lifestyle may have led to altered microbiota: sedentary and overweight individuals and athletes. From the studies analyzed, it appears that in sedentary and overweight subjects, these supplements lead to a reduction in systemic inflammation and regulate metabolism, for example, by improving insulin sensitivity. Even more, symbiotics (prebiotics+probiotics) amplify the above benefits. In addition, studies on athletes show that the effectiveness of such modulating agents of the microbiota influence both sports performance and post-exercise recovery. Indeed, probiotic intake reduces oxidative stress, improves immune function, and minimizes gastrointestinal symptoms associated with intense training, while symbiotics and prebiotics, by stimulating the production of short-chain fatty acids, improve physical endurance and muscle recovery. What emerges from this review, therefore, is that prebiotics, probiotics, and symbiotics represent promising tools both for improving the metabolic health and inflammatory status of sedentary individuals and for optimizing performance and recovery in athletes. Nevertheless, further research remains necessary to define more effective strains and dosages for each category.