Calcium intake and risk of prostate cancer: A systematic review and dose-response meta-analysis of prospective cohort studies.

[BACKGROUND] The association between high calcium intake and prostate cancer (PCa) risk is only weak, and the dose-response relationship between the two remains unclear. Therefore, we conducted a systematic review and dose-response meta-analysis to evaluate the relationship between calcium intake and PCa risk.

[METHODS] The databases were searched up to September 2024. Random-effects models were employed to pool effect sizes (ESs) with 95 % confidence intervals (CIs) for the highest versus lowest intakes of total, dietary, supplemental, dairy and non-dairy calcium. Linear and non-linear dose-response analyses were performed to assess the relationships between them.

[RESULTS] 21 prospective cohort studies were included in this meta-analysis. High intakes of total, dietary, and dairy calcium were associated with an increased risk of PCa. The summary ESs were 1.08 (95 % CI 1.01-1.15), 1.16 (95 % CI 1.08-1.24), and 1.13 (95 % CI 1.02-1.24), respectively. Supplemental calcium and non-dairy calcium intakes were not significantly associated with PCa risk. Linear dose-response analysis indicated that dietary (P-linear < 0.001) and dairy calcium intakes (P-linear = 0.02) were positively associated with PCa risk, and total calcium intake was possibly linearly related to PCa risk (P-linear = 0.06). An additional intake of 300 mg/day of total, dietary, and dairy calcium is linked to approximately 2 %, 6 %, and 5 % increases in PCa risk, respectively. No non-linear dose-response relationships were observed between calcium intake and PCa risk.

[CONCLUSIONS] These results demonstrate higher intakes of total, dietary, and dairy calcium were associated with an increased risk of PCa. Future research should provide more detailed results, including risks between different sources of calcium and PCa subtypes.