Dairy Products, Dietary Calcium and Vitamin D Intake as Risk Factors for Prostate Cancer: A Meta-Analysis of 26,769 Cases From 45 Observational Studies

Abstract

In this study, we examined the available evidence and sources of heterogeneity for studies of dairy products, calcium, and vitamin D intake and the risk of prostate cancer. We pooled data from 45 observational studies using a general variance-based, meta-analytic method employing CIs. Summary relative risks (RRs) were calculated for specific dairy products such as milk and dairy micronutrients. Sensitivity analyses were performed to test the robustness of these summary measures of effect. Cohort studies showed no evidence of an association between dairy [RR = 1.06; 95% confidence interval (CI) = 0.92–1.22] or milk intake (RR = 1.06; 95% CI = 0.91–1.23) and risk of prostate cancer. This was supported by pooled results of case-control analyses (RR = 1.14; 95% CI = 1.00–1.29), although studies using milk as the exposure of interest were heterogeneous and could not be combined. Calcium data from cohort studies were heterogeneous. Case-control analyses using calcium as the exposure of interest demonstrated no association with increased risk of prostate cancer (RR = 1.04; 95% CI = 0.90–1.15). Dietary intake of vitamin D also was not related to prostate cancer risk (RR = 1.16; 95% CI = 0.98–1.38). The data from observational studies do not support an association between dairy product use and an increased risk of prostate cancer.

ACKNOWLEDGMENTS

This study was supported by a grant from the National Dairy Council, Rosemount, Illinois.

Notes

^a Abbreviations are as follows: RR, relative risk; CI, confidence interval; FFQ, Food Factor Questionnaire; CA, cancer; NG, not given; PSA, prostate-specific antigen; BMI, body mass index; Hx, history; SU.VI.MAX, Supplementation en Vitamines et Mineraux Antioxydants study; ATBC, Alpha-Tocopheral, Beta-Carotene Cancer Prevention Study; HHP, Honolulu Heat Program; NHANES I, National Health and Nutrition Examination Survey I; NHEFS, National Health and Nutrition Examination Survey Epidemiological Follow-up Study.

^b Highest vs. lowest intake categories.

^c Mortality study.

^d Milk RRs adjusted for calcium (provide separate analysis for dairy foods adjusted for calcium intake).

^a Abbreviations are as follows: CA, cancer; Y, yes; N, no; RR, relative risk; CI, confidence interval; FFQ, Food Factor Questionnaire; P, population; Hospital; Hx, history; BMI, body mass index; PSA, prostate-specific antigen.

^b Dietary information based on intake during adolescence.

^c Via PSA.

^a Abbreviations are as follows: RR, relative risk; CI, confidence interval.