Association between Vitamin D Supplementation and Cancer Mortality: A Systematic Review and Meta-Analysis
What this study found
Vitamin D3 supplementation did not reduce overall cancer mortality (RR 0.96, 95% CI 0.80–1.16) or overall cancer incidence (RR 0.99, 95% CI 0.93–1.06). Lung cancer mortality decreased (RR 0.63, 95% CI 0.45–0.90). Daily dosing regimens were associated with lower cancer mortality than intermittent dosing (RR 0.84, 95% CI 0.72–0.97). Evidence quality: moderate for cancer mortality; high for cancer incidence. Authors conclude that vitamin D supplementation does not reduce total cancer mortality; dosing frequency may influence site-specific outcomes; further RCTs are needed to clarify effects on…
- Study & population
- Adults (≥18 years) with diverse health conditions; 12 randomized controlled trials (RCTs), including quasi-randomized and cluster-randomized designs; total participants 72,669; follow-up up to ~5 years.
- Intervention
- Vitamin D3 (cholecalciferol) supplementation with varying regimens (oral) across trials, including daily, weekly, monthly, or yearly dosing; doses ranged from 800 IU/day to 500,000 IU per dose; durations spanned roughly 2 to 5 years; calcium co-therapy was used in some regimens.
- Key limitation
- Heterogeneity in dosing regimens and co-therapy across trials; limited power for site-specific cancer outcomes; reliance on published trials reporting cancer outcomes; some risk of bias in included trials; results may not generalize to all populations.
View source
Open PDFOriginal abstract
Simple Summary It has been questioned whether vitamin D supplements can reduce the mortality and incidence of tumors. In this systematic review and meta-analysis of 12 randomized controlled trials with a total of 72,669 participants, vitamin D supplementation could not reduce the cancer mortality or cancer incidence. Our results suggest a reconsideration of the previous view that vitamin D supplementation could reduce overall cancer mortality is needed. Abstract Background: Vitamin D deficiency is related to increased cancer risk and deaths. However, whether vitamin D supplementation reduces cancer mortality remains unclear, and several randomized controlled trials yield inconsistent results. Methods: Medline, Embase, and the Cochrane Central Register of Controlled Trials were searched from their inception until 28 June 2022, for randomized controlled trials investigating vitamin D supplementation. Pooled relative risks (RRs) and their 95% confidence intervals (CIs) were estimated. Trials with vitamin D supplementation combined with calcium supplementation versus placebo alone and recruiting participants with cancer at baseline were excluded in the present study. Results: This study included 12 trials with a total of 72,669 participants. Vitamin D supplementation did not reduce overall cancer mortality (RR 0.96, 95% CI 0.80–1.16). However, vitamin D supplementation was associated with a reduction in lung cancer mortality (RR 0.63, 95% CI 0.45–0.90). Conclusions: Vitamin D supplementation could not reduce cancer mortality in this highly purified meta-analysis. Further RCTs that evaluate the association between vitamin D supplementation and total cancer mortality are still needed.