Dairy products, calcium, phosphorous, vitamin D, and risk of prostate cancer (Sweden)

Objectives: Dairy products consistently have been associated with an increa sed risk of prostate cancer, yet the mechanism of this relationship remains unknown. Recent hypotheses propose that 1,25 dihydroxyvitamin D (1,25 D) i s protective for prostate cancer. One study in the United States found that calcium consumption, which can lower circulating 1,25 D, was associated wi th higher risk of advanced prostate cancer, and we sought to address this h ypothesis in a distinct population. Methods: We analyzed data from a population-based case-control study of pro state cancer conducted in Orebro, Sweden, with 526 cases and 536 controls. Using unconditional logistic regression models, we examined the relationshi p of dairy products, dietary calcium, phosphorous, and vitamin D with risk of total, extraprostatic, and metastatic prostate cancer. Results: Calcium intake was an independent predictor of prostate cancer (re lative risk (RR) = 1.91, 95 percent confidence interval (CI) 1.23-2.97 for intake greater than or equal to 1183 vs. < 825 mg/day), especially for meta static tumors (RR = 2.64, 95 percent CI 1.24-5.61), controlling for age, fa mily history of prostate cancer, smoking, and total energy and phosphorous intakes. High consumption of dairy products was associated with a 50 percen t increased risk of prostate cancer. Conclusions: Our results support the hypothesis that high calcium intake ma y increase risk of prostate cancer, and this relation may underlie previous ly observed associations between dairy products and prostate cancer.