Last Updated on August 21, 2025 by Royce Pierpont
Long-distance running has long been hailed as a cornerstone of a healthy lifestyle, with benefits ranging from improved cardiovascular health to enhanced mental well-being. But a groundbreaking study has sparked a heated debate in the medical community, suggesting that while running may reduce the risk of colon cancer for most, extreme endurance running could pose unexpected risks for younger adults. This nuanced finding challenges the conventional wisdom that more exercise is always better, prompting runners and health enthusiasts alike to rethink their approach to fitness and cancer prevention.
The Protective Power of Running
For decades, research has consistently shown that regular physical activity, including running, can significantly lower the risk of chronic diseases, including colon cancer. According to a comprehensive review of population-based studies, individuals who engage in moderate to vigorous exercise, such as running for at least 150 minutes per week, can reduce their colon cancer risk by 25-30%. This protective effect is attributed to several biological mechanisms: running improves digestion by speeding up gut motility, reduces inflammation through the release of anti-inflammatory cytokines, and helps maintain a healthy body weight, which is critical since obesity is a known risk factor for colon cancer.
The American Cancer Society estimates that in 2025, approximately 153,020 new cases of colorectal cancer will be diagnosed in the United States alone, with colon cancer accounting for a significant portion. Globally, the International Agency for Research on Cancer (IARC) reports around 1.9 million new colorectal cancer cases annually, making it the third most common cancer worldwide. Regular physical activity, such as running, has been shown to lower this risk by promoting a healthy gut microbiome and reducing the time potential carcinogens spend in the colon.
Dr. Sameer Gupta, Head of Oncosurgery at DPU Super Specialty Hospital in Pune, India, emphasizes, “Active individuals who exercise regularly have a significantly lower risk of bowel cancer compared to those leading sedentary lifestyles. Exercise enhances gut health, reduces inflammation, and helps control weight, all of which are critical for cancer prevention.” These findings are supported by a 2024 study published in The Lancet, which found that consistent physical activity could reduce bowel cancer risk by up to 11% when performed at optimal times, such as morning or evening.
For colon cancer survivors, the benefits of running are equally compelling. A 2025 study published in the journal Cancer followed 3,000 colon cancer patients over six years and found that those who engaged in regular moderate exercise, such as running or jogging, experienced a 28% lower risk of cancer recurrence and a 37% reduction in overall mortality compared to those who received only health advice. “Exercise creates a hostile environment for cancer cells,” explains Dr. Maria Diaz, a lead researcher in the study. “It reduces insulin levels, boosts immune function, and lowers inflammation, all of which help prevent cancer from returning.”
The Unexpected Twist: Risks of Extreme Endurance
While moderate running appears to be a boon for colon health, a surprising study from the Inova Schar Cancer Institute in Fairfax, Virginia, has raised eyebrows by suggesting that extreme endurance running—such as marathons and ultramarathons—may increase the risk of precancerous growths in younger adults. The study, published in August 2025, examined 100 marathon and ultramarathon runners aged 35 to 50 who underwent colonoscopies. Shockingly, nearly half had colon polyps, and 15% had advanced adenomas—precancerous growths with a higher likelihood of developing into colon cancer. This rate is significantly higher than the 4.5-6% prevalence of advanced adenomas in the general population of similar age and even surpasses the 12% rate among Alaska Natives, a group known for elevated colon cancer risk.
Dr. Timothy Cannon, the study’s lead researcher, was inspired to conduct the research after treating three young, highly active patients with advanced colon cancer, all of whom were avid long-distance runners. “These patients were the picture of health—lean, active, and in their 30s and 40s,” Cannon noted. “It made me wonder if extreme endurance running could be a factor we’ve overlooked.”
The study’s findings suggest that the intense physiological stress of long-distance running may play a role. Prolonged, high-intensity exercise can lead to chronic inflammation, immune suppression, and oxidative stress, all of which may contribute to the formation of colon polyps. Additionally, extreme runners often follow high-calorie diets to sustain their energy needs, which may include processed foods or excessive red meat—both linked to increased colon cancer risk. The study emphasizes the need for further research to confirm these findings, as its small sample size limits its generalizability.
Balancing the Benefits and Risks
The Inova study has sparked a lively debate among experts. While some argue that the findings highlight a potential downside to extreme endurance running, others caution against overreacting. Dr. Megan Rossi, a gut health expert, points out that the broader body of evidence still overwhelmingly supports exercise as a protective factor against colon cancer. “The benefits of running far outweigh the risks for most people,” she says. “But this study reminds us that more isn’t always better. Balance is key.”
For the average runner, the message is clear: moderate, consistent exercise remains one of the most effective ways to reduce colon cancer risk. The American College of Sports Medicine recommends aiming for 150-300 minutes of moderate-intensity aerobic activity per week, combined with strength training. Activities like jogging, brisk walking, or cycling can provide the same benefits as running without the potential risks associated with extreme endurance.
For marathoners and ultramarathoners, the study underscores the importance of vigilance. Regular screening, such as colonoscopies, is critical, especially for those with a family history of colorectal cancer or other risk factors like inflammatory bowel disease. The U.S. Preventive Services Task Force lowered the recommended screening age to 45 in 2020 due to rising rates of young-onset colorectal cancer, and experts now suggest that high-risk groups, including extreme athletes, may benefit from starting screenings as early as 40.
Lifestyle Tips for Colon Cancer Prevention
Beyond exercise, lifestyle plays a crucial role in colon cancer prevention. A diet rich in fiber, fruits, vegetables, and whole grains supports gut health and reduces cancer risk. The National Cancer Institute recommends consuming at least 30 grams of fiber daily, found in foods like leafy greens, berries, lentils, and oats. Conversely, diets high in red and processed meats, such as bacon or deli slices, are linked to a higher risk of colon cancer due to carcinogenic compounds formed during cooking or processing.
Other modifiable risk factors include smoking and excessive alcohol consumption, which increase colon cancer risk by 18% and up to 50%, respectively, according to recent studies. Maintaining a healthy body weight is also critical, as obesity is associated with a 30-40% increased risk of colorectal cancer. Incorporating small changes, such as choosing plant-based proteins, limiting alcohol to one drink per day for women or two for men, and quitting smoking, can significantly lower risk.
The Rising Tide of Colon Cancer in Young Adults
The Inova study comes at a time when colon cancer rates are rising among younger individuals. According to the American Cancer Society, colorectal cancer is projected to become the leading cause of cancer-related deaths in the U.S. for adults aged 20-49 by 2030. Millennials born between 1981 and 1996 face twice the risk of colorectal cancer compared to those born in 1950, driven by lifestyle factors like poor diet, sedentary behavior, and obesity. Environmental factors, such as exposure to microplastics and gut bacterial toxins like colibactin, may also contribute.
Early detection remains the most effective tool for combating colon cancer. Symptoms such as changes in bowel habits, rectal bleeding, unexplained weight loss, and persistent fatigue should not be ignored, particularly in those over 45 or with a family history. “If you notice a sudden shift in symptoms, don’t wait,” advises Dr. Rossi. “A colonoscopy can catch polyps before they turn cancerous, saving lives.”
A Call for Balance and Awareness
The debate over long-distance running and colon cancer highlights the importance of personalized health strategies. For most people, running offers a powerful, natural way to protect against colon cancer while boosting overall health. However, for extreme endurance athletes, the Inova study serves as a cautionary tale, emphasizing the need for moderation, regular screenings, and a balanced lifestyle.
As research continues to unravel the complex relationship between exercise and cancer risk, one thing is certain: knowledge is power. By staying informed, listening to their bodies, and working with healthcare professionals, runners can continue to reap the rewards of their favorite activity while minimizing potential risks. Whether you’re a casual jogger or an ultramarathoner, the path to colon health starts with smart choices and a commitment to balance.
