J Cancer 2015; 6(9):913-921. doi:10.7150/jca.12162

Research Paper

Association between Dietary Vitamin C Intake and Risk of Prostate Cancer: A Meta-analysis Involving 103,658 Subjects

Xiao-Yan Bai1, Xinjian Qu2, Xiao Jiang1, Zhaowei Xu1, Yangyang Yang1, Qiming Su2, Miao Wang1✉, Huijian Wu1, 2✉

1. School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China
2. School of Life Science and Medicine, Dalian University of Technology, Panjin, China

Abstract

We attempted to systematically determine the association between dietary intake of vitamin C and risk of prostate cancer. PubMed and Embase were searched to obtain eligible studies published before February 2015. Cohort or case-control studies that reported the relative risk (RR)/odds ratio (OR) estimates with 95% confidence intervals (CIs) for the association between vitamin C intake and prostate cancer risk were included. Eighteen studies regarding dietary vitamin C intake were finally obtained, with a total of 103,658 subjects. The pooled RR of prostate cancer for the highest versus the lowest categories of dietary vitamin C intake was 0.89 (95%CI: 0.83-0.94; p = 0.000) with evidence of a moderate heterogeneity (I2 = 39.4%, p = 0.045). Meta-regression analysis suggested that study design accounted for a major proportion of the heterogeneity. Stratifying the overall study according to study design yielded pooled RRs of 0.92 (95%CI: 0.86-0.99, p = 0.027) among cohort studies and 0.80 (95%CI: 0.71-0.89, p = 0.000) among case-control studies, with no heterogeneity in either subgroup. In the dose-response analysis, an inverse linear relationship between dietary vitamin C intake and prostate cancer risk was established, with a 150 mg/day dietary vitamin C intake conferred RRs of 0.91 (95%CI: 0.84-0.98, p = 0.018) in the overall studies, 0.95 (95%CI: 0.90-0.99, p = 0.039) in cohort studies, and 0.79 (95%CI: 0.69-0.91, p = 0.001) in case-control studies. In conclusion, intake of vitamin C from food was inversely associated with prostate cancer risk in this meta-analysis.

Keywords: vitamin C, dietary intake, prostate cancer, risk, meta-analysis

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How to cite this article:
Bai XY, Qu X, Jiang X, Xu Z, Yang Y, Su Q, Wang M, Wu H. Association between Dietary Vitamin C Intake and Risk of Prostate Cancer: A Meta-analysis Involving 103,658 Subjects. J Cancer 2015; 6(9):913-921. doi:10.7150/jca.12162. Available from http://www.jcancer.org/v06p0913.htm