The association between vitamin C and breast cancer, prostate cancer and colorectal cancer: A systematic review and meta-analysis

For a comprehensive evaluation and due to the inconsistent results of previous studies, we performed this meta-analysis with the aim of vitamin C effect on breast cancer and prostate cancer and colorectal cancer. PubMed, Scopus and Web of Science were searched to identify studies on the association between vitamin C and breast cancer, prostate cancer and colorectal cancer through September 11, 2023. The pooled RR and the 95% confidence intervals were used to measure the association between vitamin C and breast cancer, prostate cancer and colorectal cancer by assuming a random effects meta-analytic model. Newcastle-Ottawa scale was used for quality appraisal. A total of 69 studies were included. The pooled RR for the association between vitamin C (dietary) and breast cancer in the cohort study was 0.99 [95% CI: 0.95, 1.03], but the pooled RR in the case-control study was 0.72 [95% CI: 0.60, 0.85]. No association was found between vitamin E (supplemental, total intake) and breast cancer in studies. The pooled RR for the association between vitamin C (dietary) and prostate cancer was 0.88 [95% CI: 0.77, 1.00], which represents a decrease in prostate cancer. No association was found between vitamin C (supplemental) and prostate cancer in studies. The pooled RR for the association between vitamin C (dietary) and colorectal cancer was 0.55 [95% CI: 0.42, 0.73], which represents a decrease in colorectal cancer. Our analysis shows an inverse significant relationship between vitamin C (dietary) and breast cancer in the case-control study. Also between vitamin C (dietary) and prostate cancer and colorectal cancer in studies, which represents a decrease in cancers.