Warning Signs of Poor Gut Health in Endurance Athletes

How to avoid issues and maximize performance

By Jennifer A. Kurtz, PhD, CSCS, CISSN, EP-C

Due to the intensity of their training and the physical stress that accompanies it, endurance athletes are often faced with unique health challenges. One such challenge that can significantly impact performance and overall well-being is gut health. Approximately 70% of immune health is located in the gut (8), and poor gut health can manifest in various ways, from digestive health to hormone production, mood, sleep quality, and the risk of chronic diseases (13). To name a couple examples, gut dysbiosis, an imbalance in gut bacteria, can lead to systemic inflammation and joint pain (14), while poor nutrient absorption due to an unhealthy gut can cause chronic fatigue and low energy levels (9). Therefore, it is crucial for endurance athletes to understand the early warning signs of poor gut health and take proactive measures. By identifying warning signs like digestive issues, frequent illness, fatigue, inflammation, and mood swings, athletes can avoid the downstream effects of poor gut health.

Digestive Issues

Endurance athletes often experience digestive symptoms like bloating, gas, diarrhea, and constipation, which are brought on or worsened by the physical stress of intense training. There are several potential reasons for this. First, during strenuous exercise, the body prioritizes sending blood to the working muscles to supply oxygen and nutrients, reducing blood flow to the digestive system. This redistribution, known as splanchnic hypoperfusion, can slow digestion, leading to gastrointestinal (GI) function issues such as cramping, bloating, or nausea (13).

Additionally, high-impact activities like running create repetitive jostling of the intestines that can aggravate the digestive tract and contribute to issues like diarrhea or "runner’s gut." Finally, prolonged endurance exercise, especially in hot environments, can worsen intestinal permeability, commonly known as "leaky gut." This allows harmful substances like toxins and undigested food to enter the bloodstream, triggering inflammation and immune responses. Such imbalances can lead to bloating, gas, and diarrhea, contributing to fatigue and discomfort during exercise. Addressing these challenges requires a combination of diet, supplementation, hydration, exercise moderation, and pre-exercise nutrition, which can mitigate digestive symptoms and support overall gastrointestinal well-being (4). 

Inflammation

Gut dysbiosis, which is an imbalance in the gut bacteria, can lead to systemic inflammation that manifests as joint pain and other inflammatory conditions (14). As mentioned above, an imbalanced gut, especially in a "leaky gut" state, can also contribute to chronic inflammatory conditions such as inflammatory bowel disease and irritable bowel syndrome. (5,14). This type of chronic inflammation can negatively affect endurance performance by impairing muscle function, increasing fatigue, and hindering recovery (12). Furthermore, inflammation can reduce the body's ability to efficiently utilize energy stores, ultimately limiting athletic performance. Maintaining a healthy gut barrier through dietary interventions and probiotics can help reduce intestinal permeability and mitigate inflammation.  

Frequent Illness

Because 70% of the immune system is located in the gut, compromised gut health can lead to an increase in infections (9). In healthy athletes with good gut health, exercise enhances immune function by promoting the circulation of immune cells and reducing chronic inflammation (10). However, excessive training without adequate recovery can suppress the immune system by increasing levels of stress hormones like cortisol, which can in turn impair immune cell activity and increase susceptibility to infections, particularly upper respiratory tract infections (10). The gut microbiome plays a central role in immune health by helping to regulate inflammation and support the production of protective compounds like short-chain fatty acids (11). Therefore, maintaining a diverse and balanced microbiome through proper nutrition and probiotics can help mitigate the immunosuppressive effects of overtraining.

Fatigue and Low Energy

In addition to the chronic inflammation discussed earlier, gut dysbiosis can also impair nutrient absorption in endurance athletes. The gut microbiota, which is the community of microorganisms living in the digestive tract, plays a crucial role in breaking down food and synthesizing essential nutrients (7). An impairment in this process can end up exacerbating deficiencies in key nutrients like iron and vitamin B12, further contributing to chronic fatigue and low energy levels. Maintaining a healthy gut through a balanced diet rich in fiber, probiotics, and prebiotics can support optimal nutrient absorption and energy levels.

Mood Swings and Mental Health Issues

Gut imbalances don’t just affect digestion—they can also impact mental well-being. The gut and brain are connected through the gut-brain axis, a communication network that allows gut bacteria to influence mood, stress levels, and cognitive function (6). When gut health is compromised, this connection can be disrupted, potentially leading to issues like anxiety, depression, and mood swings (6). Furthermore, the gut produces many of the same neurotransmitters, such as serotonin, that the brain uses to regulate mood. An unhealthy gut can alter the production and function of these neurotransmitters, negatively impacting mental health (6). 

How MultiV and MultiV-PRO Can Help

By understanding the warning signs of poor gut health and addressing them early, endurance athletes can maintain better overall health and performance. Supplements like MultiV and MultiV-PRO from First Endurance are specifically designed to support the unique needs of endurance athletes by providing the essential vitamins, minerals, prebiotics, and anti-inflammatory ingredients necessary to restore and maintain a healthy gut microbiome (2, 3).  

Comprehensive Nutrient Support: Both MultiV and MultiV-PRO provide a broad spectrum of essential vitamins and minerals that support overall health, including gut health. They ensure that athletes get the nutrients they need to maintain a healthy gut microbiome.

Prebiotics and Probiotics: MultiV-PRO includes agave inulin, a prebiotic that supports the growth of beneficial gut bacteria. This helps maintain a healthy balance of gut microbiota, which is crucial for optimal digestive health. 

Anti-Inflammatory Ingredients: MultiV-PRO contains Levagen®+, a compound known for its anti-inflammatory properties. This can help reduce gut inflammation and improve overall gut health.

Enhanced Recovery: The inclusion of polyphenol-rich extracts in MultiV-PRO aids in faster recovery and tissue repair, which can be beneficial for gut health, especially after intense training sessions.

Immune Support: Both supplements include ingredients that support immune function, helping to reduce the frequency of illnesses that can be exacerbated by poor gut health.

Conclusion

Maintaining good gut health is essential for endurance athletes to perform at their best, and recognizing the warning signs of poor gut health and taking proactive steps with the help of supplements like MultiV and MultiV-PRO from First Endurance can make a significant difference. These supplements provide comprehensive support to ensure that athletes can train harder, recover faster, and maintain optimal health. By addressing gut health, endurance athletes can not only improve their performance, but enhance their overall quality of life. Remember, a healthy gut is the foundation of a healthy body.
  
1.             Beane KE, Redding MC, Wang X, et al. Effects of dietary fibers, micronutrients, and phytonutrients on gut microbiome: a review. Applied Biological Chemistry 64: 1-18, 2021.
2.             Bucci LR. MultiV-PRO: Premium Immune System Health for Athletes.
3.             Bucci LR. MultiV-PRO: Pushing Performance Beyond 100%.
4.             de Oliveira EP, Burini RC. Food-dependent, exercise-induced gastrointestinal distress. Journal of the International Society of Sports Nutrition 8: 1-7, 2011.
5.             Escalante J, Artaiz O, Diwakarla S, McQuade RM. Leaky gut in systemic inflammation: exploring the link between gastrointestinal disorders and age-related diseases. GeroScience: 1-22, 2024.
6.             Farmer AD, Randall HA, Aziz Q. It's a gut feeling: how the gut microbiota affects the state of mind. The Journal of physiology 592: 2981-2988, 2014.
7.             Flint HJ, Scott KP, Louis P, Duncan SH. The role of the gut microbiota in nutrition and health. Nature reviews Gastroenterology & hepatology 9: 577-589, 2012.
8.             Kerksick CM, Wilborn CD, Roberts MD, et al. ISSN exercise & sports nutrition review update: research & recommendations. Journal of the international society of sports nutrition 15: 38, 2018.
9.             Khaledi M, Darvishi M, Sameni F, et al. Association between exercise and changes in gut microbiota profile: a review. Sport Sciences for Health 20: 273-286, 2024.
10.          Nieman DC, Wentz LM. The compelling link between physical activity and the body's defense system. Journal of sport and health science 8: 201-217, 2019.
11.          Nogal A, Valdes AM, Menni C. The role of short-chain fatty acids in the interplay between gut microbiota and diet in cardio-metabolic health. Gut microbes 13: 1897212, 2021.
12.          O’Brien MT, O’Sullivan O, Claesson MJ, Cotter PD. The athlete gut microbiome and its relevance to health and performance: a review. Sports Medicine 52: 119-128, 2022.
13.          Ribichini E, Scalese G, Cesarini A, et al. Exercise-Induced Gastrointestinal Symptoms in Endurance Sports: A Review of Pathophysiology, Symptoms, and Nutritional Management. Dietetics 2: 289-307, 2023.
14.          Varghese S, Rao S, Khattak A, Zamir F, Chaari A. Physical Exercise and the Gut Microbiome: A Bidirectional Relationship Influencing Health and Performance. Nutrients 16: 3663, 2024.