Which lifestyle factor is a risk factor for colorectal cancer?

• A. Low-fiber diet
• B. Vitamin C supplementation
• C. Regular exercise
• D. High-fiber diet

Answer: (C)

Lifestyle influences colorectal cancer risk, especially diet and physical activity. A diet low in fiber is associated with increased risk because fiber helps keep stool bulky and moves it through the colon faster, reducing the duration of exam exposure to potential carcinogens and supporting a healthier gut microbiome. Regular exercise, in contrast, is protective: it improves bowel motility, helps with weight control and insulin sensitivity, and lowers inflammation, all of which reduce cancer risk. High-fiber diets tend to lower risk as well, by the same mechanisms that fiber provides. Vitamin C supplementation has not shown a consistent, proven protective effect against colorectal cancer. So, among the options, the lifestyle factor that increases risk is a low-fiber diet.