Vitamin D Intake and the Risk of Colorectal Cancer: An Updated Meta-Analysis and Systematic Review of Case-Control and Prospective Cohort Studies

Study answer

What this study found

Dietary vitamin D intake is associated with reduced CRC risk in case-control studies (OR 0.75; 95% CI 0.67-0.85). In prospective cohorts, dietary vitamin D shows no significant association with CRC incidence (HR 0.94; 95% CI 0.79-1.11). For colorectal cancer subsites, dietary vitamin D reduces colon cancer risk (OR 0.82; 0.67-0.98) and rectal cancer risk (OR 0.67; 0.51-0.87), with stronger effect in women for rectal cancer (0.57; 0.39-0.82). Supplemental vitamin D shows inverse associations in case-control data for colon cancer (0.57; 0.37-0.88) but not rectal cancer; total vitamin D shows…

Study & population

Observational meta-analysis of case-control and prospective cohort studies in adults from multiple countries; 31 case-control studies (47,540 cases; 70,567 controls) and prospective cohorts with 14,676 CRC-incident cases among 808,130 participants; follow-up ranged from 5 to 16 years.

Key limitation

Heterogeneity across study designs and populations; residual confounding and measurement errors in vitamin D intake assessment; limited publication bias assessment due to small numbers of studies; outliers influencing results in some analyses; inability to determine optimal dose or exposure duration; sun exposure and…

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Original abstract