Which vitamin has a protective effect against colon cancer?

Vitamin D Has Protective Effect Against Colon Cancer

Vitamin D is the vitamin that has a protective effect against colon cancer. 1

Evidence for Vitamin D's Protective Role

• Higher circulating 25-hydroxyvitamin D (25(OH)D) concentrations are associated with a statistically significant reduction in colorectal cancer risk, with optimal concentrations appearing to be 75-100 nmol/L 1
• A large international pooling project of 17 cohorts found that for each 25 nmol/L increment in circulating 25(OH)D, colorectal cancer risk was 19% lower in women and 7% lower in men 1
• Vitamin D has anti-proliferative effects in various tissues including the colon and has been shown to modify the Wnt signaling pathway, which is implicated in colorectal carcinogenesis 2

Evidence Against Other Options

Vitamin K

• There is no significant evidence in the provided guidelines supporting vitamin K's protective effect against colorectal cancer 2

Folic Acid

• Despite observational studies suggesting potential benefits, randomized controlled trials have shown that folic acid supplementation does not reduce colorectal cancer risk 2
• The AGA Clinical Practice Update specifically states: "On the basis of current data, there is no clear role for folic acid supplementation in colorectal neoplasia prevention" 2
• Some studies even suggest folic acid supplementation may increase the risk of advanced adenomas, multiple adenomas, and serrated polyps 2

Vitamin C

• While some observational studies have shown protective effects of vitamin C against colorectal cancer 3, more recent guidelines and systematic reviews do not support a clear protective role for vitamin C supplementation in colorectal cancer prevention 2, 4

Important Considerations Regarding Vitamin D

• The protective effect of vitamin D appears to be dose-dependent, with deficient levels (<30 nmol/L) associated with 31% higher colorectal cancer risk compared to sufficient levels 1
• The optimal 25(OH)D concentrations for colorectal cancer risk reduction (75-100 nmol/L) appear higher than current Institute of Medicine recommendations that are based solely on bone health 1
• The protective effect of vitamin D is more pronounced in women (19% lower risk per 25 nmol/L increment) than in men (7% lower risk) 1

Caveats and Limitations

• Some clinical trials examining vitamin D supplementation have shown mixed results:
  • The Women's Health Initiative trial found no effect of vitamin D plus calcium supplementation on colorectal cancer incidence 2
  • A multicenter trial found that vitamin D supplementation did not reduce adenoma recurrence 2
• Some evidence suggests that calcium plus vitamin D supplementation may actually increase the risk of sessile serrated lesions 6-10 years after supplementation begins 2
• Results from the Australian D-Health Trial, which randomized over 21,000 participants to 5 years of cholecalciferol vs placebo, are not expected until at least 2025 2

Despite some mixed results from supplementation trials, the most recent and comprehensive evidence from the international pooling project of 17 cohorts strongly supports vitamin D's protective role against colorectal cancer, particularly at optimal blood concentrations of 75-100 nmol/L 1.