Calcium, Vitamin D, and Dairy Product Intake and Prostate Cancer Risk: The Multiethnic Cohort Study

Song-Yi Park; Suzanne P. Murphy; Lynne R. Wilkens; Daniel O. Stram; Brian E. Henderson; Laurence N. Kolone

Disclosures

Am J Epidemiol. 2007;166(11):1259-1269. 

In This Article

Abstract and Introduction

High intakes of calcium and dairy products have been suggested to be related to prostate cancer risk. Such associations were examined in the Multiethnic Cohort Study (1993-2002) among 82,483 men who completed a detailed quantitative food frequency questionnaire. During a mean follow-up of 8 years, 4,404 total cases of prostate cancer were identified. In Cox proportional hazards models, no association was found between calcium and vitamin D intake and total, advanced, or high-grade prostate cancer risk, whether for total intake, intake from foods, or intake from supplements, among all male participants or among nonusers of supplemental calcium. No association of calcium or vitamin D intake was seen across racial/ethnic groups. In analyses of food groups, dairy product and total milk consumption were not associated with prostate cancer risk. However, low-/nonfat milk was related to an increased risk and whole milk to a decreased risk of total prostate cancer; after stratification, these effects were limited to localized or low-grade tumors. Although the findings from this study do not support an association between the intakes of calcium and vitamin D and prostate cancer risk, they do suggest that an association with milk consumption may vary by fat content, particularly for early forms of this cancer.

High intakes of calcium and dairy products have been suggested to play a role in prostate cancer development via vitamin D metabolism.[1,2,3] A hypothesized mechanism is that high calcium consumption lowers the level of circulating 1,25-dihydroxyvitamin D, an inhibitor of prostate carcinogenesis.[2] Indeed, a recent meta-analysis of prospective studies reported that high calcium intake was related to a 39 percent increase in risk for total prostate cancer and a 46 percent increase in risk for advanced prostate cancer, and that high dairy product intake was associated with an 11 percent increase in total prostate cancer risk and a 33 percent increase in advanced prostate cancer risk.[4] These results suggest that high intakes of calcium and dairy products may affect tumor differentiation as well as development. Among individual prospective cohort studies, some studies support the positive associations,[5,6,7,8] but other investigations are not supportive.[9,10,11,12,13] Furthermore, the only randomized controlled clinical trial found no increase in prostate cancer risk with calcium supplementation over a period of 4 years.[14]

Studies that investigated individual types of dairy products have suggested that a positive association may be limited to low- or nonfat milk rather than whole milk, cheese, yogurt, or other dairy items,[3,5,8] but an explanation for this specificity is not clear. With the recommendations for daily calcium intake ([1],200 mg) and low- or nonfat milk (3 cups/0.71 liter) or equivalent milk product consumption for adults,[15,16] as well as the known health benefits of adequate calcium intake, the role of calcium as a potential risk factor for prostate cancer needs to be clarified. In this analysis, we investigated the intakes of calcium, vitamin D, and dairy products in relation to prostate cancer risk in a large, multiethnic cohort where the incidence of the disease differs greatly by ethnicity.

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