Overview

• Observational studies suggest higher vitamin D levels are associated with a reduced risk of colorectal cancer, with some data showing up to a 58% lower risk in certain groups.
• Randomized controlled trials (RCTs) provide mixed results, showing no consistent evidence for prevention but potential survival benefits for existing colorectal cancer patients.
• Preclinical research indicates vitamin D’s active form may suppress inflammation, regulate cell growth, and enhance immune responses, supporting its biological plausibility in cancer prevention.
• Colorectal cancer rates among adults aged 25–49 have risen by 52% since the early 1990s, prompting calls for multifaceted prevention approaches including screening and lifestyle changes.
• Experts recommend maintaining adequate vitamin D levels for overall health but caution against relying on supplements alone as a preventive measure for colorectal cancer.