High intake of specific carotenoids and flavonoids does not reduce the risk of bladder cancer

An analysis of a previously completed Spanish multicentric case-control study of bladder cancer was carried out using new available data on the contents in foods of specific carotenoids (alpha-carotene, beta-carotene, lutein, and lycopene) and flavonoids (quercetin, kaempferol, myricetin, and luteolin) to investigate the relationship of these phytochemicals with bladder cancer. The study included 497 cases first diagnosed with bladder cancer, 547 neighborhood controls, and 566 hospitals controls, matched by gender, age, area of residence, and hospital. Usual food intake was estimated using a dietary history questionnaire administered by trained interviewers. None of the specific carotenoids and none of the specific flavonoids have been found to be significantly associated with bladder cancer risk in this analysis. The adjusted odds ratios for subjects in the highest quartile of intake with respect to subjects in the lowest quartile were 1.36 (95% confidence interval = 0.94-1.95) for total carotenoid intake and 1.23 (95% confidence interval = 0.85-1.79) for total flavonoid intake. The result of this study does not support the hypothesis that intake of specific carotenoids and flavonoids is protective against bladder cancer risk.