If you’re like most athletes, you rarely think about your gut. You put all your energy into your training and nutrition and assume your gut will take care of itself.
In fact, your gut and the bacteria that live there have a huge impact on your athletic performance. The gut plays a primary role in your ability to handle stress, recover from workouts, and perform at your best. It affects mood, energy levels, metabolic function, and how you feel on a day-to-day basis.
Why Is A Healthy Gut Important For Athletes?
It’s helpful to understand how the gut works if you want it to function optimally. There is just a single layer of cells protecting your body from everything that passes through your gut. Working properly, this cell layer allows all of the nutrients, amino acids, and healthy compounds from food to be absorbed into your body.
Other compounds, such as waste products or toxins, are kept out and eliminated. A healthy gut does a good job of eliminating all the junk that is harmful to your body.
Each cell in the cell layer is held together by a “tight junction.” The tight junctions allow nutrients into the body and keep toxins out. All kinds of things including antibiotics, drug therapies, hormones like cortisol, and immune factors can break down the tight junctions, increasing their permeability.
A classic example is with ibuprofen. Combining ibuprofen and exercise is a bad idea because during exercise, the body reroutes blood away from the GI tract to the skin, muscles, heart, and lungs. For some reason, the combination of reduced blood flow and ibuprofen can harm the cells in the intestines, damaging the integrity of the tight junctions.
When this happens, the gut lining is more permeable and not as protective, making it more likely that toxins will escape and enter the bloodstream. At the same time, absorption of nutrients is compromised and chronic inflammation may develop.
What are some other ways poor digestion impacts function and performance?
Gut Health Regulates Inflammation
Inflammation isn’t strictly localized to the GI tract when gut health is compromised. An unhealthy gut can lead to the production of harmful compounds that cause inflammation in other parts of the body. For example, TMAO, a compound produced when gut bacteria feed on certain amino acids, can lead to plaque buildup up in the arteries, raising heart disease risk.
Athletes are especially susceptible to this due to the fact that they often have a high protein intake and a relatively low fiber intake, even if they are on a high-carbohydrate diet for performance. This combination is dangerous for the gut.
High-protein diets can have a negative affect on the beneficial bacteria in the gut through amino acid fermentation, which produces harmful metabolites, such as the TMAO mentioned above. Animal proteins appear to be the most dangerous.
Fiber has a protective effect, in part because the indigestible carbs in fiber serve as food for beneficial bacteria. Additionally, most high-fiber complex carbs are packed with phytonutrients that have anti-inflammatory action and reduce inflammation associated with certain protein foods.
A recent study illustrates how a certain kind of fiber called resistant starch can protect the gut during a high-protein intake. In this study, diets high in either red meat or casein protein resulted in an increase in GI inflammation. Adding resistant starch from maize to the high-protein diets counteracted the negative effects and protected the gut.
Gut Health & Detoxification
Fiber and resistant starch also promote proliferation of healthy bacteria, which are part of the foundation of gut health. As mentioned above, the gut flora feed on what we eat. Amino acids in meat allow harmful bacteria to thrive, whereas most forms of fiber promote the health of beneficial bacteria. Additionally, the type and number of bacteria will impact the integrity of the tight junctions.
High levels of cortisol and adrenaline, which are common with heavy training loads and competition, can negatively impact your gut microbiota. These hormones loosen the tight junction protein structures so that toxins slip out of the protective GI tract and into the bloodstream, making you feel ill and causing an immune response.
Poor GI health can also inhibit excretion of harmful compounds from the body. For example, we are exposed to many chemicals that mimic the hormone estrogen in water, food, and personal care products, and these compounds need to be safely eliminated through the GI tract.
In order for this to happen, dietary fiber is necessary to bind to estrogen in the digestive tract so that it can be excreted from the body. Dietary fiber also reduces the amount of an enzyme (called B-glucouronidase) that breaks apart bound estrogen that is on its way out of the body. When the estrogen breaks free in the large intestine, it re-enters circulation, damaging cells and causing inflammation.
A Healthy Gut = A Healthy Brain
Emerging research is highlighting how what’s going on in your gut impacts how your brain functions. Your gut produces a number of powerful neurotransmitters that regulate mood, appetite, and energy levels. For example, serotonin, a critical transmitter that boosts mood and conveys feelings of satisfaction and calm is produced in the gut.
GABA (regulates blood pressure and heart rate), dopamine (impacts energy and motivation), and neuropeptide Y (affects food intake and resilience to stress) are other transmitters released from the gut, especially in response to stress. When gut health is compromised, production of these transmitters get out of balance, triggering depression, mental health disorders, and poor cognition.
How To Know If Your Gut Is Healthy?
Do you suffer problems with gastrointestinal function such as constipation, bloating, discomfort during training, flatulence, or diarrhea? Do you have a chronic cold or low energy despite what should be adequate recovery?
If you can answer yes to any of those symptoms, you can bet you aren’t getting everything possible out of your nutrition. All of these symptoms are common in both athletes and the general population and they are indicators that gut health is not optimal!
The first step to fixing your gut is to start with what you’re eating:
Remove alcohol, unnecessary medications (including over the counter drugs like ibuprofen), caffeine, added sugar, and processed food, especially if it contains artificial additives.
Favor whole foods over supplements and processed foods. In an effort to get all their calories in macros in, it’s normal for athletes to rely on sports gels, powders, and drinks. Although there is a time and place for sports nutrition, these products are associated with GI problems and don’t provide the high-quality nutrition available from a whole food diet designed around vegetables, nuts, legumes, meat, fish, dairy, fruit, and whole grains.
Replace refined carbs with whole carbs. Athletes often eat refined carbs to abandon, but this is not the best approach for a healthy gut, particularly if you have a high protein intake. Complex, fiber-rich carbs are necessary because they provide phytonutrients that counter inflammation.
Another reason whole, high-fiber carbs are necessary is that they allow for the production of short chain fatty acids (SCFA) from gut bacteria, such as butyrate, acetate, and propionate, which have an anti-inflammatory effect in the body. SCFAs directly affect gut function by improving the pH of the colon, increasing intestinal motility, and optimizing gut permeability. SCFA may also be protective against the high levels of training stress experienced by many athletes, improving function of the hypothalamic pituitary axis that regulates hormone release.
Although undigested protein foods that reach the intestines are harmful for the gut, it’s important for athletes to include high-quality protein foods. Best results will come from thoroughly chewing proteins and pairing them with fiber-rich vegetables. Inadequate protein intake impairs immunity and increases the likelihood of infection and permeability in the gut.
Eat your healthy fats. The typical recommendation is to avoid fat when athletes are struggling with GI distress, however, a range of healthy fats are necessary to offset intestinal inflammation: Nuts, avocado, coconut oil, olive oil, butter, dairy, fats from animal protein, and eggs can all have beneficial effects on the gut assuming you’re not intolerant to these foods. The exact composition of fat in the diet will be individual, but there is evidence that the gut can adapt to a higher fat, lower carb diet over time and GI problems can be avoided.
Identify and avoid foods that are harmful to your unique gut. Every person’s gut is different. Some people can’t tolerate dairy, others need to avoid grains, and for others gluten is a no-no. More common offenders are eggs, animal protein, soy, yeast, and corn.
Supplement with a high-quality probiotic that is guaranteed through the date of expiration. Get adequate prebiotics (fiber that serves as fuel for healthy gut bacteria) from a wide variety of veggies or supplement with resistant starch (bought as unmodified potato starch).
Take digestive enzymes to ensure complete digestion of proteins.
Give your digestive system a rest with some form of fasting. Because they need so many calories to fuel training, many athletes are constantly eating, never giving their digestive system a chance to “recover.” Fasting stimulates motility, which is the intestines contracting to maintain a downward flow of food through the intestinal tract. Occasionally including a short-term fast in which you skip breakfast or dinner can give the GI tract time to perform “housekeeping” functions to keep it healthy.
Once you have the basics of gut health dialed in, we can focus on training the gut for optimal athletic performance.
Many endurance or team sport athletes who need to consume liquids and carbohydrates during training complain about drinks accumulating in the stomach and feeling bloated. Reports show that by progressively training while ingesting larger volumes of liquid can “train” the stomach to tolerate more food or liquid and is not perceived of as full.
For example, one study of trained runners found that stomach comfort significantly improved over time as the athletes practiced training with a high intake of a carb-electrolyte solution.
Most interesting, research shows that when athletes increase carbohydrate intake, absorption rate and quantity increases. The quantity of insulin-related peptides and GLUT transporters increase, allowing for greater absorption of carbohydrates to fuel high-intensity training.
Training the gut to “handle” carbs is especially relevant for athletes on a lower-carb diet or who are restricting calories to lose body fat. When the daily carb load is reduced, the capacity to absorb carbs in the stomach decreases and GI problems increase. Since the gut is so adaptable, it’s recommended to include training with a high-carb intake into the weekly routine to train the gut to absorb and burn more carbs, which should results in less GI distress and better performance.
Certain nutrients are essential for optimal gut health:
Vitamin D modulates inflammation in the GI tract and balances gut microflora.
Zinc has powerful anti-inflammatory properties and taking it has been shown to enhance restoration of mucus in the intestines.
Magnesium is another foundational nutrient and studies suggest changes in healthy gut bacteria when there is inflammation in the presence of magnesium deficiency.
Fish oil may be protective for gut health. In one study, patients with inflammatory bowel diseases who supplemented with fish oil had greater mucus production, which protects the gut by helping to keep food proteins and pathogens from passing through the tight junctions that regulate the intestines.
Glutamine and glycine are two amino acids that help repair the gut lining for better absorption of nutrients.
Actively focus on stress reduction. Balancing cortisol and lowering your daily load of stress may be the most important thing for improving your gut besides dealing with food intolerances because of how it impacts function of the gut, harming the tight junctions and increasing oxidative stress in the GI tract. What does a stress management plan look like in real life?
Get good sleep by adopting a set bed and wakeup. Take time out to slow down, doing deep breathing, yoga or meditation. Focus on the post-exercise time for recovery with optimal nutrition, muscle recovery work (foam rolling, stretching, massage), and relaxation (listen to music, hangout with friends, take a hike).