Can Probiotics Boost Athletic Performance? Review Shows What Works, What Remains Unproven

Scientists have discovered how targeted probiotics can help athletes go further, recover faster and stay healthier if the right strains are chosen and research gaps are filled.

In a recent review published in the journal Frontiers in Nutrition, researchers compiled and summarized current scientific evidence to clarify the relationships and relationships between probiotics, the gut microbiome, and athletes’ physical performance. The goal of the review is to use this information to help athletes, their coaches, and healthcare professionals make informed decisions about training methods that optimize performance and minimize adverse physiological effects.

The review highlights the multifaceted potential benefits of probiotic supplementation for athletes, including modulation of inflammation, improvement of gut barrier function and evidence of alteration of metabolic pathways. However, it says that the effects are highly strain-specific, dose- and sport-specific and that not all studies show positive results. The review suggests that incorporating probiotic supplementation into athletes’ training plans may be beneficial for some, but more research is needed before universal recommendations can be made.

There is currently insufficient evidence to state that probiotic supplementation is necessary for injury prevention or that it will consistently provide measurable benefits in performance. Current studies are highly strain specific and context dependent, highlighting the need for standardised and generalisable data, particularly for strength sports.

Prerequisites

Professional elite sports are all about the pursuit of the smallest advantage, with athletes looking for any way they can to improve performance and recovery. Decades of research have confirmed that training and nutrition are the foundations of athletic development. Surprisingly, a key component of physiological well-being (and therefore recovery and performance) – the trillions of microbes that make up the gut microbiome – remains largely ignored in most traditional training regimes.

The gut microbiome is a complex ecosystem that is actively involved in nutrient absorption, immune function, and inflammation regulation, all of which are critical factors for athletic success. As a result, there is a growing body of research in the fields of nutrition and sports that is attempting to elucidate the two-way links between gut microbiome properties and athletic performance.

In particular, such research is focused on the use of probiotic supplements to reduce common complaints in athletes (such as gastrointestinal upset in long-distance runners or upper respiratory infections that can reduce performance) and to improve overall performance.

Research overview

This review aims to systematically assess the current scientific landscape, identifying the pros and cons of specific probiotic strains, current limitations of probiotic research for athletes, and current research frontiers that may allow athletes to train harder with less risk of injury than ever before.

Peer-reviewed publications investigating the topics of “probiotics”, “microbiome” and “exercise performance” published between 2015 and 2024 were identified using customized keyword searches in PubMed and Scopus. All identified publications were screened by title, abstract and full text, and both animal and human studies were included in the review.

The review results were classified into three categories to improve the specificity of recommendations:

1. A sport based on endurance.
2. Sports with intermittent load.
3. Strength training.

For each category, the review provides a clear overview of what is known, what is promising, and where critical gaps in our knowledge remain. The review also addresses a fourth group—wheelchair athletes—as an understudied population with respect to probiotic use.

Review results

Endurance athletes

This subcategory of athletes (runners, cyclists) is the most studied in terms of the gut microbiome. A review shows that exercise-induced gastrointestinal disorders are the most common physiological problem among endurance athletes. Encouragingly, several studies using multi-ingredient probiotic supplements have reported significant reductions in gastrointestinal symptoms after probiotic supplementation.

Certain probiotic strains have additionally been linked to direct improvements in performance parameters. For example, supplementation of Bifidobacterium lactis BL-99 to long-distance cross-country skiers improved lipid metabolism and VO₂ max. Similarly, a 16-week study in road cyclists using a multi-component formula showed improvements in aerobic capacity and time to exhaustion for some parameters, while other studies found no significant effects on VO₂ max or time to exhaustion.

Mechanistic assessments attribute the observed benefits to reduced systemic inflammation (reduced levels of proinflammatory cytokines such as TNF-α and IL-6) and reduced oxidative stress. However, not all studies demonstrated beneficial effects, and some showed no significant changes in key performance measures. The review also discusses mechanisms such as the gut-liver axis and gut-brain axis that may mediate some of the observed physiological effects.

It is important to note that a 6-week synbiotic (probiotic + prebiotic) intervention in soccer players was associated with increases in maximum heart rate (HRmax) and lactate clearance rate compared to controls; however, the increase in HRmax is physiologically counterintuitive to improve recovery and may reflect limitations in interpretation or reporting in the original article.

Athletes with intermittent loads

Although this category of athletes (e.g., soccer and basketball players) has not been studied as extensively as endurance athletes, probiotic supplementation has also shown benefits for them. Specifically, probiotics significantly reduce the incidence and duration of upper respiratory tract infections (URTIs), thereby reducing the number of missed training sessions and competitions. A 6-week synbiotic intervention in soccer players significantly reduced URTI symptoms and also increased HRmax and lactate clearance rate compared to the control group.

Several studies have demonstrated the benefits of probiotics for mental health and mood. In particular, 6 weeks of Lactobacillus casei supplementation in badminton players resulted in reduced stress and anxiety levels, as well as improved aerobic capacity. However, other studies in dancers and football players found no significant effects on pain, fatigue, or certain performance measures, highlighting the variability of results.

Power athletes

Compared to endurance and intermittent athletes, strength athletes (e.g., bodybuilders) remain significantly less studied. Limited evidence suggests that probiotic supplementation with Bacillus coagulans may enhance branched-chain amino acid (BCAA) absorption and improve leg press strength in trained men, suggesting potential benefits for both physiology and performance measures. Other studies in strength-trained athletes have reported improvements in some measures of strength and body composition; however, results remain inconsistent and data are sparse. Factors such as probiotic dosage, duration, and frequency of administration may influence results and require further study.

Wheelchair athletes

Wheelchair athletes are an understudied population with unique challenges. Limited evidence suggests that probiotic supplementation may reduce inflammatory markers and improve gut microbiome diversity; however, results are mixed, with some studies showing reduced inflammation but no significant improvement in gastrointestinal symptoms.

Conclusions

Probiotic supplementation is a promising but challenging strategy for athletes. The review highlights that a one-size-fits-all approach is ineffective: benefits vary widely by strain, dosage, and sport. While endurance and intermittent athletes may gain measurable benefits in gut health, immunity, and aerobic performance, current evidence is lacking for those involved in strength and power sports.

Some studies report no significant improvements in key performance or health metrics, highlighting the need for further rigorous and standardized studies to confirm the efficacy of probiotics in athletic settings. Future studies should clearly document supplementation protocols and clarify mechanisms of action, such as modulation of the gut-brain and gut-liver axes.

At present, probiotic supplementation represents a promising, but not guaranteed or universal, method for optimising athletic performance, and its use should be considered on an individual basis until more conclusive evidence is available.