Researchers looked at 18 different studies to see if changing your gut bacteria through food, supplements, or exercise could help athletes perform better. Your gut is home to trillions of tiny bacteria that affect your health in many ways. Scientists wanted to know if making these bacteria healthier could boost athletic performance. However, the studies they reviewed had very different methods and results, making it hard to draw clear conclusions. The bottom line: while gut bacteria are important for health, we don’t yet have strong evidence that targeting them specifically improves exercise performance in healthy, active people.

The Quick Take

  • What they studied: Whether changing your gut bacteria through diet, supplements, or exercise could improve athletic performance and endurance
  • Who participated: The review analyzed 18 published studies involving healthy, active adults who tried various interventions like special diets, probiotic supplements, or exercise programs
  • Key finding: Changes in gut bacteria were unpredictable and usually very small, and there was no clear connection between these changes and better exercise performance
  • What it means for you: While keeping your gut bacteria healthy is important for overall wellness, spending money on special supplements or diets specifically to boost athletic performance isn’t yet backed by solid scientific evidence

The Research Details

This was a systematic review, which means researchers searched through scientific databases to find all published studies on this topic. They looked at five major databases of medical research up through February 2025. They only included studies where healthy, active adults received either a supplement, special diet, or exercise program, and compared their results to a control group that didn’t receive the intervention. The researchers then looked at whether the interventions changed the bacteria in people’s stool samples and whether those changes affected exercise performance like running speed, strength, or endurance.

Because the 18 studies they found used very different methods—different supplements, different diets, different ways of measuring bacteria, and different ways of testing performance—the researchers couldn’t combine all the results together statistically. Instead, they described what each study found and looked for patterns across all of them.

A systematic review is a powerful way to understand what science currently knows about a topic. By looking at all available studies together rather than just one study, researchers can see the big picture. This approach helps identify whether findings are consistent across different research groups or whether results are all over the place. In this case, the mixed results suggest we need better, more standardized research before making recommendations.

The researchers followed strict guidelines (called PRISMA) for conducting systematic reviews, which is a good sign. However, they noted that the original 18 studies had significant quality issues: different interventions made it hard to compare results, different ways of measuring gut bacteria made comparisons difficult, and most studies didn’t look at whether changes in bacteria actually connected to performance improvements. Only one study found a clear positive result (increased a beneficial compound called acetate from yogurt with specific bacteria). These limitations mean the current evidence is weak and inconclusive.

What the Results Show

The main finding was that changes in gut bacteria were highly unpredictable and usually very small across the studies reviewed. Some people’s bacteria changed a lot, some changed a little, and some didn’t change at all—even when they received the same intervention. This variability makes it nearly impossible to predict who might benefit and who might not.

When researchers looked at short-chain fatty acids (special compounds produced by gut bacteria that may be important for health), they found that very few studies even measured these. Only one study showed a clear increase in a beneficial compound called acetate, which came from eating yogurt containing a specific type of bacteria called Bifidobacterium animalis subsp. lactis BL-99.

Most importantly, only seven of the 18 studies even looked at whether changes in gut bacteria connected to better exercise performance. Of those seven studies, the results were unclear or inconclusive. No study showed a consistent pattern of improved athletic performance linked to changes in gut bacteria.

The review identified several other important issues: the types of supplements and diets used varied widely between studies, making it impossible to say which approaches might work best; the methods for analyzing gut bacteria differed significantly, which means researchers might have missed important changes or counted things differently; and most studies were relatively short-term, so we don’t know if any benefits would last over months or years. Additionally, many studies had design flaws that could have affected their results, such as small numbers of participants or lack of proper control groups.

This systematic review builds on earlier research showing that gut bacteria are important for overall health and digestion. Previous studies have suggested that certain probiotics might help with some health issues, but this review specifically looked at whether these bacteria changes help athletic performance—a much more specific question. The findings suggest that while gut health matters generally, the specific link to exercise performance is not yet proven, unlike some other health benefits where the evidence is stronger.

The biggest limitation is that the 18 studies reviewed were so different from each other that researchers couldn’t combine their numbers statistically. This is like trying to compare apples and oranges—the studies used different interventions, measured bacteria in different ways, and tested performance differently. Most studies were small and short-term. Many didn’t measure whether bacteria changes actually connected to performance changes. The quality of the original studies was often poor, with issues like not properly controlling for other factors that might affect results. Finally, all studies involved healthy, active adults, so we don’t know if results would be different for other groups like older adults, people with health conditions, or non-athletes.

The Bottom Line

Based on current evidence, there is insufficient support (low confidence) for recommending special supplements or diets specifically designed to change gut bacteria for the purpose of improving exercise performance in healthy, active adults. However, general recommendations to eat a balanced diet rich in fiber, fruits, and vegetables remain sound for overall health and may support healthy gut bacteria as a side benefit. If you’re interested in probiotics, discuss with a healthcare provider whether they might help with specific health concerns, but don’t expect them to boost athletic performance.

Athletes and active people curious about optimizing performance should know that current evidence doesn’t support expensive probiotic supplements or special diets for this purpose. However, people interested in general gut health, digestion, or immune function may still benefit from dietary approaches that support healthy bacteria. This review doesn’t apply to people with specific digestive conditions or diseases, who should follow their doctor’s advice. Supplement companies marketing performance benefits based on gut bacteria should be viewed skeptically until stronger evidence emerges.

If you were to try dietary changes to support gut health, you might notice improvements in digestion within days to weeks. However, expecting improvements in athletic performance from these changes is not supported by current evidence. Any real benefits would likely take weeks to months to appear, if they appear at all. The research suggests we need several more years of well-designed studies before we’ll know if gut bacteria targeting can truly enhance exercise performance.

Want to Apply This Research?

  • Track your dietary fiber intake (target 25-30 grams daily) and note any changes in digestion, energy levels, and workout performance over 8-12 weeks. Record the types of foods eaten (especially whole grains, fruits, vegetables, and fermented foods) rather than focusing on specific probiotic supplements.
  • Instead of buying expensive probiotic supplements, focus on eating more fiber-rich whole foods like oats, beans, berries, and leafy greens, which naturally support healthy gut bacteria. Log these foods in your app and track your overall wellness and performance metrics to see if you notice any personal benefits.
  • Monitor general wellness indicators like energy levels, digestion quality, sleep quality, and workout performance metrics over 12 weeks. Use the app to identify patterns between dietary choices and how you feel, rather than expecting dramatic performance improvements. Share data with a healthcare provider if you have specific health concerns.

This summary is based on a systematic review of published research and is for educational purposes only. It should not replace professional medical advice. Before starting any new supplement regimen or making significant dietary changes, especially if you have existing health conditions or take medications, consult with your healthcare provider or a registered dietitian. The research reviewed here involves healthy, active adults and may not apply to other populations. Individual results vary, and what works for one person may not work for another.