I Can Feel it in my Gut (Again)

A while back I wrote about the latest hot topic in science, gut bacteria, and how it could potentially impact athletic performance. At the time, there were still a lot of unanswered questions. But, with a new review recently published on the topic, I feel it’s a good time to revisit things and see what new lessons we’ve learned that can be applied to maximizing performance.

First, let’s start with a refresher on gut bacteria. The term “gut bacteria” refers to the trillions of bacteria living in your gut, primarily the large intestine. The gut includes other cells as well and this diverse ecosystem (or “microbiome”) lives in a largely symbiotic relationship with you. In general, the greater diversity of cells/bacteria that make up the microbiome, the better.

A number of studies have highlighted that the microbiome is influenced by a variety of things such as diet and disease. Of particular interest to athletes/coaches are the studies that report relationships between exercise and the microbiome. More specifically, studies indicate that athletes have a greater microbiome diversity compared to non-athletes and even VO2max is positively associated with the microbiome.

Some of the more recent findings discussed in the review by Mancin and colleagues suggest that the microbiome has an impact on muscle and therefore performance. In studies conducted on mice, some gut bacteria are shown to improve glycogen content in the muscle (this is important considering glycogen is an important fuel source during exercise). Additionally, running capacity and muscle function have also been shown to be impacted by certain bacteria within the microbiome.

Unfortunately, the research still doesn’t tell us what the optimal microbiome looks like for all athletes. There are just too many individual differences between people for there to be one “ideal” microbiome. That being said, there are still some dietary considerations you can take into account to ensure your microbiome trends towards what might be considered more optimal.

In my previous post, I discussed probiotics and how there’s some evidence to suggest they add bacteria diversity to the gut. Mancin and colleagues in their review, describe how probiotics decrease the risk for respiratory infections that can come from periods of intense training. Some have also shown that probiotics improve performance. It should be noted that there’s still a lot we don’t know about probiotics. For instance, some evidence suggests probiotics don’t increase microbiome diversity in healthy individuals, so how probiotics actually improve health/performance is not well understood. Nonetheless, probiotic foods like yogurt and kimchi are delicious and I’ll keep eating them just in case.

Mancin and colleagues also highlight that diets low in insoluble fiber and high in red meat lead to a lower diversity of bacteria as well as promote the production of harmful byproducts that can then negatively impact immune function and muscle glycogen content. Therefore, limiting the intake of red meat as well as increasing the amount of insoluble fiber (found in fruits and vegetables, particularly green leafy vegetables) can be beneficial. There are some caveats. Increasing the amount of insoluble fiber can lead to bloating and other gaseous concerns that can negatively impact performance – when it comes to fiber, remember that less is better before a workout.

Now, where does this leave us? Well, much of the research in this field is still correlational and does not determine causation. In other words, there’s potential for the microbiome to be the next big thing we can “train” to improve performance but there’s still a lot we don’t know. Hopefully we’ll know all the answers in a few years and I can update you with another blog post. In the meantime, the best advice is to keep eating healthy with lots of leafy greens, fruits, and vegetables. Thanks for reading!