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

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.

Lower rates of cancer and all-cause mortality in an Adventist cohort compared with a US Census population.

BACKGROUND: Previous research suggests that Adventists, who often follow vegetarian diets, live longer and have lower risks for many cancers than others, but there are no national data and little published comparative data for black subjects. METHODS: This study compared all-cause mortality and cancer incidence between the nationally inclusive Adventist Health Study 2 (AHS-2) and nonsmokers in US Census populations: the National Longitudinal Mortality Study (NLMS) and its Surveillance, Epidemiology, and End Results substudy. Analyses used proportional hazards regression adjusting for age, sex, race, cigarette smoking history, and education. RESULTS: All-cause mortality and all-cancer incidence in the black AHS-2 population were significantly lower than those for the black NLMS populations (hazard ratio [HR] for mortality, 0.64; 95% confidence interval [CI], 0.59-0.69; HR for incidence, 0.78; 95% CI, 0.68-0.88). When races were combined, estimated all-cause mortality was also significantly lower in the AHS-2 population at the age of 65 years (HR, 0.67; 95% CI, 0.64-0.69) and at the age of 85 years (HR, 0.78; 95% CI, 0.75-0.81), as was cancer mortality; this was also true for the rate of all incident cancers combined (HR, 0.70; 95% CI, 0.67-0.74) and the rates of breast, colorectal, and lung cancers. Survival curves confirmed the mortality results and showed that among males, AHS-2 blacks survived longer than white US subjects. CONCLUSIONS: Substantially lower rates of all-cause mortality and cancer incidence among Adventists have implications for the effects of lifestyle and perhaps particularly diet on the etiology of these health problems. Trends similar to those seen in the combined population are also found in comparisons of black AHS-2 and NLMS subjects.