Song D1,2, Deng Y1,2, Liu K3, Zhou L1,2, Li N1,2, Zheng Y2, Hao Q2, Yang S2, Wu Y2, Zhai Z2, Li H4, Dai Z1,2.
Aging (Albany NY). 2019 Dec 28;11(24):12708-12732. doi: 10.18632/aging.102597. Epub 2019 Dec 28.
Epidemiological studies have indicated that blood vitamin D levels are linked to cancer. Here we conducted a dose-response meta-analysis based on published observational studies to evaluate the association of vitamin D intake and blood vitamin D levels with breast cancer susceptibility. PubMed, EMBASE, and Web of Science databases were searched up to January 2019. The pooled odds ratio (OR) and 95% confidence intervals (CIs) were extracted to estimate the risk. We identified 70 relevant studies on blood vitamin D levels (50 studies) and vitamin D intake (20 studies), respectively. Linear and nonlinear trend analyses were performed and showed that an increase in blood vitamin D levels by 5 nmol/l was associated with a 6% decrease in breast cancer risk (OR = 0.94, 95% CI = 0.93-0.96). Similar results were obtained for premenopausal (OR = 0.96, 95% CI = 0.93-0.99) and postmenopausal women (OR = 0.96, 95% CI = 0.94-0.98). The pooled OR of breast cancer risk for a 400IU/day increase in vitamin D intake was 0.97 (95% CI = 0.92-1.02).
In conclusion, we found that breast cancer risk was inversely related to blood vitamin D levels; however, no significant association was observed in vitamin D intake.