Reducing Colorectal Cancer Risk: Screening, Diet, and Healthy Habits   

Colorectal cancer is one of the most common cancers in the United States and has traditionally been considered a disease of older adults. In recent years, however, rates have been rising in adults under age 50.¹ At the same time, rates have declined in older adults, largely due to increased screening. The reasons for this shift are likely due to several factors not yet fully understood; however, changes in environment and lifestyle factors are believed to play an important role.  

These trends highlight the importance of both early detection through screening and long-term risk reduction through healthy lifestyle habits. Screening can detect cancer early and remove precancerous polyps, while healthy lifestyle habits, including diet and physical activity, are areas where people can take actionable steps to lower their risk. Research suggests that up to half of colorectal cancer cases may be preventable through diet and lifestyle change.^2–5 

In this article, PHM experts review the latest evidence on screening, diet, and other lifestyle strategies that may help reduce colorectal cancer risk.  

Screening: Early detection 

Screening plays a central role in colorectal cancer prevention because it can identify precancerous growths and detect cancer at an earlier, more treatable stage. Many colorectal cancers develop slowly from polyps in the colon. When these polyps are found during screening, they can be removed before cancer develops. Recommendations for when and how to screen depend on age and individual risk factors. People at higher risk, including Black Americans, may benefit from discussing screening with their healthcare provider. 
 

When should screening begin?^6,7 

Most adults at average risk should begin screening at age 45. However, professional guidelines recommend earlier screening for adults with certain risk factors, including:  

• A family history of colorectal cancer 

• Certain inherited cancer syndromes 

• Inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis. 

It is important for these adults to consult with a qualified healthcare provider to establish an appropriate screening timeline and cadence based on their higher risk profile. 

Ways to screen for colorectal cancer^6,7 

There are several available screening options. Colonoscopy is considered the gold standard because it allows doctors to examine the colon directly and remove precancerous polyps during the procedure. Stool-based tests, which detect hidden blood or abnormal DNA in the stool that may signal cancer or precancerous changes, can also be used in people who are at average risk. 

The recommended frequency of screening depends on the testing option. Colonoscopies are recommended every 10 years, while stool-based tests are recommended to be completed more frequently, such as annually or every 3 years.^6,7 

Symptoms that should not be ignored^6,7 

Although colorectal cancer may not always cause symptoms early on, certain warning signs should warrant prompt evaluation by a physician. These include: 

• Rectal bleeding 

• Persistent changes in bowel habits (ongoing diarrhea or constipation) 

• New onset iron deficiency anemia (low hemoglobin and ferritin levels, suggestive of possible blood loss in stool) 

• Unexplained weight loss 

Diet: Risk modification and prevention 

A growing body of research shows that long-term lifestyle habits play an important role in shaping risk over time. Large studies across many populations consistently show that dietary patterns, along with other lifestyle factors such as body weight, physical activity, alcohol use, and smoking, influence long-term risk.^3–5,8–11 Research increasingly demonstrates that overall dietary patterns influence risk more than individual foods. Rather than focusing on individual “good” or “bad” foods, finding a healthy balance over time can most effectively reduce risk. 

Overall eating patterns matter most 

Diets associated with reduced risk 

Plant-rich, high-fiber diets have been consistently associated with lower colorectal cancer risk. People who follow plant-rich diets have about 15–30% lower risk of colorectal cancer compared with those who follow less healthy diets.^5,6,11,12 Examples of these include Mediterranean-style diets, DASH diets, and other plant-forward eating patterns.  

These diets tend to emphasize whole, minimally processed foods, including whole grains, legumes, vegetables, and fruit, with a moderate amount of dairy and limited consumption of red and processed meats. They are naturally high in fiber, which helps support healthy digestion and beneficial gut bacteria. When gut bacteria break down fiber by fermentation, they produce short-chain fatty acids such as butyrate, which may help reduce inflammation, strengthen the gut barrier, and support healthy colon cells.^2,12 

Diets associated with increased risk 

In contrast, Western-style diets have been linked to higher colorectal cancer risk. Studies suggest these dietary patterns are associated with about 20–30% higher risk of colorectal cancer and precancerous polyps.^3,4,13 Similar patterns have also been linked to early-onset colorectal cancer in younger adults.¹⁴ 

These diets tend to be higher in red and processed meats, refined grains, sugar-sweetened beverages, and ultra-processed foods. Diets like these may lead gut bacteria to produce metabolites that are at odds with beneficial short-chain fatty acids, such as hydrogen sulfide and ammonia, that may cause inflammation, damage the gut barrier, and compromise the development of healthy colon cells.¹⁵ 

Specific foods may also play a role 

While overall dietary patterns appear most important, research has also identified several individual foods and nutrients that may influence risk. 

Foods associated with increased risk 

Some specific foods have consistently been linked with higher risk, including processed meats (bacon, sausage, deli meats) and higher intake of red meat (beef, pork, lamb, etc.).^2–4,8,9 Drinking alcohol increases risk, especially with heavier drinking.^3,16  

Foods associated with reduced risk 

Other foods have consistently been linked with lower risk, including whole grains and foods high in dietary fiber.^2–4 Soluble fiber dissolves in water to form a viscous, gel-like substance that improves nutrient absorption and supports a healthy gut microbiome. Some common sources include oats, legumes, apples, and flaxseed. Insoluble fiber remains largely intact during digestion to increase stool bulk and intestinal transit time, which promotes bowel regularity. Some common sources include whole grains, leafy green vegetables, nuts, and seeds.  

Higher intake of calcium, milk, and dairy products has also been associated with lower colorectal cancer risk.^2,3,16 There is evidence that calcium may help reduce exposure of the colon lining to potentially harmful substances.^8,9 Eating Greek yogurt is also associated with lower risk.⁴ 

In addition, some specific nutrients naturally found in a healthy diet may play supportive roles in colon health and cancer prevention, such as vitamin D and folate (vitamin B9). Research findings are still evolving.^2,9  

Other lifestyle factors: Risk modification and prevention 

Diet is only one part of the picture. The greatest reductions in colorectal cancer risk are seen when healthy eating is combined with other positive lifestyle habits. Maintaining a healthy weight, limiting alcohol, and avoiding smoking are all effective ways to reduce risk. Engaging in regular physical activity (150–300 minutes of moderate-intensity or 75–150 minutes of high-intensity aerobic activity per week) is also important. Studies have shown that if this level of activity is difficult to achieve, even small changes like reducing daily sedentary time and breaking up long sitting periods can be beneficial.¹⁷ All of these healthy habits work together to decrease long-term cancer risk.^5,9,10 

Actionable steps to modify risk 

Research consistently supports the following strategies to help reduce colorectal cancer risk: 

• Follow a plant-rich, colorful, high-fiber diet 

• Include calcium-rich foods such as dairy or fortified alternatives 

• Incorporate Greek yogurt or fermented dairy when appropriate 

• Limit or avoid red and processed meats 

• Limit alcohol consumption 

• Maintain a healthy weight  

• Engage in regular physical activity 

• Follow recommended colorectal cancer screening guidelines 

Lowering risk does not require perfection. Small, healthy choices made consistently over time can make a meaningful difference. 

How PHM supports early detection and risk modification 

At PHM, our Personal Care Teams help clients take a proactive approach to colorectal cancer detection and risk modification. We guide clients through established screening recommendations, interpret family history and individual risk factors to support specialized screening protocols, and develop personalized, practical diet and lifestyle strategies that support long-term health. 

References 

1. Colorectal Cancer Drops in Older Adults and Rises in Younger Ones. https://www.cancer.org/research/acs-research-news/colorectal-cancer-drops-in-older-adults-and-rises-in-young-ones.html. 

2. Song, M., Garrett, W. S. & Chan, A. T. Nutrients, Foods, and Colorectal Cancer Prevention. Gastroenterology 148, 1244-1260.e16 (2015). 

3. Vernia, F., Longo, S., Stefanelli, G., Viscido, A. & Latella, G. Dietary Factors Modulating Colorectal Carcinogenesis. Nutrients 13, (2021). 

4. Veettil, S. K. et al. Role of Diet in Colorectal Cancer Incidence: Umbrella Review of Meta-analyses of Prospective Observational Studies. JAMA Netw Open 4, e2037341 (2021). 

5. Chu, A. H. et al. Dietary-Lifestyle Patterns and Colorectal Cancer Risk: Global Cancer Update Programme (CUP Global) Systematic Literature Review. The American Journal of Clinical Nutrition 121, 986–998 (2025). 

6. Colorectal Cancer Screening Guidelines. https://www.cancer.org/health-care-professionals/american-cancer-society-prevention-early-detection-guidelines/colorectal-cancer-screening-guidelines.html. 

7. Final Recommendation Statement: Screening for Colorectal Cancer | United States Preventive Services Taskforce. https://www.uspreventiveservicestaskforce.org/uspstf/announcements/final-recommendation-statement-screening-colorectal-cancer-0. 

8. Hull, M. A. Nutritional prevention of colorectal cancer. Proceedings of the Nutrition Society 80, 59–64 (2021). 

9. Kim, S. H., Moon, J. Y. & Lim, Y. J. Dietary Intervention for Preventing Colorectal Cancer: A Practical Guide for Physicians. Journal of Cancer Prevention 27, 139–146 (2022). 

10. Tabung, F. K., Brown, L. S. & Fung, T. T. Dietary Patterns and Colorectal Cancer Risk: a Review of 17 Years of Evidence (2000–2016). Curr Colorectal Cancer Rep 13, 440–454 (2017). 

11. Zhou, E. & Rifkin, S. Colorectal Cancer and Diet: Risk Versus Prevention, Is Diet an Intervention? Gastroenterology Clinics of North America 50, 101–111 (2021). 

12. Yuan, Q. et al. Deciphering the impact of dietary habits and behavioral patterns on colorectal cancer. International Journal of Surgery 111, 2603 (2025). 

13. Fernández-Villa, T., Álvarez-Álvarez, L., Rubín-García, M., Obón-Santacana, M. & Moreno, V. The role of dietary patterns in colorectal cancer: a 2019 update. Expert Review of Gastroenterology & Hepatology 14, 281–290 (2020). 

14. Carroll, K. L., Frugé, A. D., Heslin, M. J., Lipke, E. A. & Greene, M. W. Diet as a Risk Factor for Early-Onset Colorectal Adenoma and Carcinoma: A Systematic Review. Front. Nutr. 9, (2022). 

15. Chan, D. S. M. et al. Post-diagnosis dietary factors, supplement use and colorectal cancer prognosis: A Global Cancer Update Programme (CUP Global) systematic literature review and meta-analysis. International Journal of Cancer 155, 445–470 (2024). 

16. Papier, K. et al. Diet-wide analyses for risk of colorectal cancer: prospective study of 12,251 incident cases among 542,778 women in the UK. Nat Commun 16, 375 (2025). 

17. Sun, Y., Keat, O. B. & Rajabi, S. The role of physical activity and epigenetic changes in colorectal cancer prevention. Cancer Cell Int 25, 227 (2025).