Intakes of selected nutrients, foods, and phytochemicals and prostate cancer risk in western New York

A number of epidemiological studies have suggested that diet may affect the etiology of prostate cancer, but few have investigated the impact of phytochemical intakes on this cancer. We conducted a case-control study of diet and prostate cancer in western New York involving 433 men with primary, histologically confirmed prostate cancer and 538 population-based controls, frequency matched to cases on age and county of residence. Diet was assessed with a detailed food-frequency questionnaire. We calculated daily intakes of nutrients and the phytochemicals beta-sitosterol, campesterol, stigmasterol, total phytosterols, total lignan precursors, quercetin, and kaempferol based on published food composition data. Odds ratios (ORs) and 95% confidence intervals (CIs) describing the association of prostate cancer risk with selected nutrients, phytochemicals, and food groups were estimated with unconditional logistic regression. Compared with men in the lowest quartile of intake, reduced risks were observed for men in the highest quartile of intake of vitamin C (OR = 0.49; 95% CI = 0.33-0.74), beta-carotene (OR = 0.53; 95% CI = 0.36-0.79), alpha-carotene (OR = 0.67; 95% CI = 0.47-0.97), lutein (OR = 0.55; 95% CI = 0.37-0.81), lycopene (OR = 0.62; 95% CI = 0.42-0.92), total lignan precursors (OR = 0.66; 95% CI = 0.47-0.94), quercetin (OR = 0.64; 95% CI = 0.44-0.92), and total vegetables (OR = 0.53; 95% CI = 0.36-0.79), but weak increased risks were observed for snacks and sweets (OR = 1.46; 95% CI = 0.95-2.23). Estimates associated with nutrients and phytochemicals were attenuated after adjustment for total vegetable intake. Nevertheless, our results support the hypothesis that a phytochemical-rich, plant-based diet is of importance in reducing risks of hormone-related neoplasms.