Mate and Tea Intake, Dietary Antioxidants and Risk of Breast Cancer: a Case-Control Study.

Recently, we reported an inverse association between high 'mate' intake (infusion of Ilex paraguariensis herb, a staple beverage in temperate South America) and breast cancer (BC) risk. Stronger inverse associations were found in high strata of tea, vegetable, fruit and energy intakes, and in overweight/obese women, suggesting possible roles for 'mate' mainly from its antioxidant contribution. The present study attempted to thoroughly explore possible associations among 'mate' and tea intake, dietary antioxidants and BC risk. Combining two databases of previous studies, 572 BC incident cases and 889 controls were interviewed with a specific questionnaire featuring socio-demographic, reproductive and lifestyle variables, and a food frequency questionnaire (64 items), focusing on 'mate' intake (consumer status, daily intake, age at start, age at quit, duration of habit). Food-derived nutrients were calculated from available databases. Odds ratios (OR) and their 95% confidence intervals were calculated through unconditional logistic regression, adjusting for relevant potential confounders. The highest 'mate' intake was significantly inversely associated with BC risk for both low and high carotenoids (OR=0.40 vs. 0.41), vitamin C (OR=0.33 vs. 0.50), vitamin E (OR=0.37 vs. 0.45), flavonols (OR=0.38 vs. 0.48) and reduced glutathione (OR=0.48 vs. 0.46) strata. High tea intake showed significant inverse risk associations only with high carotenoids (OR=0.41), vitamin E (OR=0.48) and reduced glutathione (OR=0.43) strata. In conclusion, a strong and inverse association for 'mate' intake and BC was found, independent of dietary antioxidant levels. Also strong inverse associations with tea intake were more evident only at high levels of certain dietary antioxidants.