How Gut Health Impacts Your Sports Performance

By Klara Kun and Gary Jomrich – August 18, 2021

The gut microbiota is one of the crucial factors that affect human health and, by extension, athletic performance. It is an essential part of a complex network of interactions between the gastrointestinal system, immune system and brain. If any external or internal factor alters this equilibrium, it will inevitably have repercussions on your overall health.

There are several ways a healthy gut can influence your performance and help you stay at your peak longer.

To enhance your athletic performance, you need nutrients in a trusted diet plan — macro and micronutrients that support all physiological functions to perform better and recover faster.

Good bacteria populating the intestine are essential for synthesizing vitamins like K, B₁, B9 and B12, minerals, and other essential nutrients. If these bacteria are in excess, or there is a presence of harmful bacteria, the digestive process slows down — consequently, the body’s ability to absorb nutrients decreases. You will get absolutely no benefits from eating healthy if your body does not absorb the nutrients you consume. The eventual deficit in essential nutrients will negatively impact your performance and recovery.

Bone health is an essential factor for athletic performance. Short-term risks like injuries or long-term risks like osteoporosis are not worth chancing. A healthy gut promotes nutrient absorption. Intestinal calcium and magnesium absorption are essential for maintaining optimal levels of these minerals and strengthening bone health.

Gut microbes, or the so-called good bacteria, help us maintain a proper-working antioxidant defense system that effectively neutralizes the excess of free radicals.

Physical activity has a beneficial effect on gut health as it can enhance the number of good bacteria. Still, harsh and long-lasting physical activity can alter the intestinal microbiota and damage the intestinal barrier. As an athlete, you should focus not only on your training programs but also on your gut health. Achieving a balanced gut microbiota should be a fixed part of every nutrition and training program. Many athletes, especially long-distance runners, experience gastrointestinal disorders during or shortly after training or competition. Maintaining your gut health can reduce and, in some cases, prevent the symptoms of gastrointestinal distress.

Every athlete knows that a good night’s sleep is the holy grail for performance and recovery enhancement. Around 80% of serotonin, which is the precursor of melatonin, is produced by gut bacteria. Low levels of this neurotransmitter can cause sleep disturbances and therefore affect your athletic performance negatively. 

A healthy gut will allow adequate water reabsorption and solute transport, resulting in better hydration.

Numerous factors can cause a reduction in the effectiveness of your immune system, especially before competitions. This could expose you to a greater risk of catching upper respiratory tract infections. The gut microbiome is closely related to the immune system. It is a bi-directional relationship that favors both parties. The gut microbiome is crucial for the development of the immune system from birth.

According to research, if you don’t consume enough fiber, your gut microbiota can cause inflammation because the bacteria in the absence of fiber attack the intestinal mucus. Mucus also acts as a protective barrier against microbes, and when they come into direct contact with the intestinal cells, they cause inflammation. Exercise-induced oxidative stress, leukocyte infiltration, and the production of pro-inflammatory cytokines cause a wide array of inflammation symptoms. High-fiber foods stimulate bacteria to produce chemical compounds beneficial to the body, such as butyrate, which, according to researchers, can protect us effectively against inflammation.

There are many ways you can improve your overall gut health. Focused training and preparation of your gastrointestinal organs will improve the absorption of nutrients during practice, training, and racing. Having a well-prepared gut will prevent bloating, flatulence or malaise. Through slow adjustments of the amounts of nutrients, the gastrointestinal system will get used to handling the quantities needed. 

Here are some valuable tips for improving your gut health: 

What to pay attention to:

  • Fermented foods such as kombucha, sauerkraut, tempeh, miso, and tofu are sources of natural probiotics.
  • To increase the influence of probiotic foods, one can combine them with foods rich in prebiotics. An example of this would be soy yogurt with fruits or seeds. Here prebiotics, probiotics and essential micronutrients are combined in one meal.
  • Drink enough and regularly! Avoid, however, sugary drinks with artificial flavorings.
  • Consume sufficient amounts of fiber: vegetables, fruits, legumes, nuts, seeds.
  • Eat foods as natural, unprocessed, regional, and organic as possible.
  • Consume an energy-rich and carbohydrate-rich diet. The intestine will adapt to this supply of nutrients and can optimally process nutrients.

What should you avoid?

  • Processed foods: This includes classic fast foods such as pizza, French fries, burgers, etc. All industrially produced foods with many production steps, such as ready-made spreads, sweets, sauces, and much more, should be avoided to support your intestines.
  • Artificial sweeteners and sugar substitutes such as aspartame, saccharin, or sucralose. Instead, use healthy alternatives like date sweetener, maple syrup, or coconut blossom sugar. In general, try to avoid foods with added sugar and use homemade dishes with natural sweeteners.
  • Avoid coffee, alcohol, and medication (antibiotics) (for medication, consult your doctor)

What to eat before training or competing?

  • Avoid high fiber meals just before exercise.
  • Avoid unfamiliar foods or combinations of ingredients.
  • You should eat your last large meal 2-4 hours before training. After that, you should eat only small, easily digestible snacks (100-300 kcal), not burden the digestive system, and use all of the energy for a successful workout.
  • Homemade smoothies or a banana are an optimal source of energy before training.
  • A handful of nuts or nut mixes provide energy, healthy fats and protein for a good workout.
  • No meals that are too fatty. Fats stay long and weigh heavily in the stomach, leading to malaise and reduced performance.
  • Make sure you consume enough carbohydrates and protein, but remember, 2 to 4 hours before an activity.
  • Avoid high-energy, hypertonic foods and drinks

A healthy gut can influence your performance and help you stay at your peak longer. Paying attention to what and when you eat will pay off in increased athletic performance. 


About the Author

Klara Kun and Gary Jomrich are the creators of TrainingMeals – a soon-to-be-released web-based solution and app for smart and effective nutrition and supplement planning for athletes. Klara is a sports nutritionist and has a passion for wholesome, healthy nutrition. Gary has years of experience in the specialty and health food industry and is a multiple Ironman athlete. Together, they spend their time studying the theory of sports nutrition and its practical implications in training and daily life. To contact Klara or Gary, email or visit


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