Vitamin D and Calcium Supplementation Reduces Cancer Risk
Keum N, Lee DH, Greenwood DC, Manson JE, Giovannucci E
JAMA Network Open • September 2019
Plain Language Summary
This large analysis of multiple studies found that taking vitamin D supplements, especially along with calcium, may help reduce the overall risk of developing cancer. The protective effect was strongest when people took at least 1000 IU of vitamin D daily. While this is promising, more research is needed to understand which specific cancers might be prevented and who benefits most.
Key Findings
- 1Vitamin D supplementation reduced total cancer incidence by 13% when combined with calcium
- 2The protective effect was more pronounced in participants with normal BMI
- 3Benefits were seen with doses of 1000 IU/day or higher
- 4No significant effect on cancer mortality alone was observed
Abstract
This meta-analysis of randomized clinical trials examined the effect of vitamin D supplementation, with or without calcium, on cancer incidence and cancer mortality. The analysis included 10 trials with 30,970 participants.
Results showed that vitamin D supplementation, particularly when combined with calcium, was associated with a statistically significant reduction in total cancer incidence (RR, 0.87; 95% CI, 0.79-0.96).
Study Limitations
- Heterogeneity in vitamin D doses and formulations across trials
- Variable baseline vitamin D status of participants
- Limited data on specific cancer types
- Most studies conducted in predominantly white populations