You have probably heard the term "leaky gut" before, but what does the science actually say about this phenomenon and how does it relate to endurance athletes?
When we talk about leaky gut, we are really referring to an increase in intestinal permeability. This does not mean that there are holes in the intestines, but rather that the spaces between the cells that make up the intestinal lining have widened. Normally, intestinal cells are closely packed next to each other to form tight junctions that only let small molecules pass from the intestines into the bloodstream. During times of increased permeability, the tight junctions loosen giving larger molecules and toxins the opportunity to leak into the bloodstream.
Increased intestinal permeability is a particularly important issue for endurance athletes because exercise has been shown to draw blood flow away from the gut which increases permeability and may lower the efficacy of the immune system. This can lead to common side effects that many endurance experience such as cramps, diarrhea, nausea, and an increased risk of infection. One study found that permeability increases with running intensity so the harder you train, the higher your risk for these adverse effects. But don’t worry, no one is telling you to lighten up on your training! There is actually a way to help prevent the exercise-induced increase in permeability: probiotics.
Probiotics have been shown to prevent intestinal permeability and even prevent exercise-induced permeability specifically. The idea is that probiotics form a protective barrier around the intestinal cells which reduces permeability and supports the immune system. This may explain why probiotic supplementation is associated with fewer gastrointestinal and respiratory illnesses in athletes.
Probiotic supplements are a great tool to help you stay healthy while training hard, but be sure to choose your probiotic wisely. If you read our post on why probiotic strains matter, you will remember that a probiotic should contain the types that have been shown to result in the benefits you are looking for you.
by Katelyn Collins
Katelyn Collins, is a future registered dietitian with a passion for probiotics, a knack for nutrition communications, and a love of athletic pursuits on both land and sea.