Dairy foods, calcium intakes, and risk of incident prostate cancer in Adventist Health Study–2

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ABSTRACT

Background

Prostate cancer is the most common noncutaneous cancer in American males. Causal links between dairy, or dietary calcium, and this cancer are considered suggestive but limited.

Objectives

To evaluate these associations in a large North American cohort, including many with no (or very low) dairy intake and much calcium from nondairy sources.

Methods

A prospective cohort study of 28,737 Seventh-day Adventist men in the United States and Canada, of whom 6389 were of black ethnicity. Diet was measured by FFQ, and 275 male participants also provided repeated 24-h dietary recalls as a calibration substudy. Incident cancers were mainly found by matching with cancer registries. Analyses used multivariable proportional hazards regressions and regression calibration for some analyses.

Results

In total, 1254 (190 advanced) incident prostate cancer cases were found during an average 7.8 y of follow-up. Men at the 90th percentile of dairy intake (430 g/d) compared with the 10th percentile (20.2 g/d) had higher prostate cancer risk (HR: 1.27; 95% CI: 1.12, 1.43). Similar findings, comparing the same g/d intakes, were demonstrated for advanced prostate cancers (HR: 1.38; 95% CI: 1.02, 1.88), for nonadvanced cases (HR: 1.27; 95% CI: 1.11, 1.45), in black participants (HR: 1.24; 95% CI: 0.98, 1.58), and when excluding vegan participants (HR: 1.22; 95% CI: 1.03, 1.43). Calibrated dairy (g/d) regressions (all participants and all prostate cancers), adjusting for dietary measurement error, found a HR of 1.75 (95% CI: 1.32, 2.32). Comparing 90th percentile intake to zero intakes (uncalibrated), the HR was 1.62 (95% CI: 1.26, 2.05). There was no evidence of an effect of higher (905 mg/d) compared with lower (349 mg/d) intakes of nondairy calcium (HR: 1.16; 95% CI: 0.94, 1.44).

Conclusions

Men with higher intake of dairy foods, but not nondairy calcium, had a higher risk of prostate cancer compared with men having lower intakes. Associations were nonlinear, suggesting greatest increases in risk at relatively low doses.

Keywords:

dairy intake
calcium intake
prostate cancer
Seventh-day Adventists
vegetarians
vegans
regression calibration
cohort study
African American

Abbreviations used:

AHS-2
Adventist Health Study–2
EPIC
European Prospective Investigation into Cancer and Nutrition
IGF-1
insulin-like growth factor 1
WCRF
World Cancer Research Fund.

Cited by (0)

Supported by the National Cancer Institute at NIH (grant 1U01CA152939), World Cancer Research Fund (grant 2009/93), and Ardmore Institute of Health. The NIH, World Cancer Research Fund, and the Ardmore Institute of Health played no part in the design, implementation, analysis, and interpretation of this data.

Current address for KJ-S: Master of Public Health Program, School of Osteopathic Medicine, University of the Incarnate Word, 7615 Kennedy Hill Dr., San Antonio, TX 78235.

Data described in the manuscript, code book, and analytic code will be made available upon request pending application and approval and payment for associated costs.

Supplemental Figure 1 and Supplemental Tables 1–4 are available from the “Supplementary data” link in the online posting of the article and from the same link in the online table of contents at https://academic.oup.com/ajcn/.