Studies of the association between
polyphenols dietary intake and
breast cancer risk have been limited due to the lack of detailed food composition tables. In addition, none has examined this association according to alcohol intake, despite the facts that alcohol is an established risk factor for
breast cancer and that the contribution of alcoholic beverages to
polyphenol intake varies according to the level of alcohol consumption. Our objectives were (1) to estimate the associations between
breast cancer risk and a wide range of dietary
polyphenols using the recently published
Phenol-Explorer database; and (2) to evaluate if/how alcohol intake modulates these relationships. 4,141 women from the SU.VI.MAX prospective cohort were followed from 1994 to 2007 (median followup: 12.6 years); 152 developed a first incident invasive primary
breast cancer. Dietary intakes were assessed by repeated 24-h records. The
Phenol-Explorer database was used to estimate
polyphenol intake. Multivariable Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95 % confidence intervals (CIs) for quartiles of
polyphenol intake. Analyses were stratified by median alcohol intake (< vs. ≥ 6.5 g/d). In non-to-low alcohol drinkers, intakes of some classes of
polyphenols were associated with decreased
breast cancer risk:
hydroxybenzoic acids (HR(Q4vsQ1) = 0.38, 95 % CI: 0.17-0.86, P (trend) = 0.005),
flavonoids (0.35, 0.17-0.75, P (trend) = 0.02),
flavonols (0.36, 0.18-0.74, P (trend) = 0.002), catechins (0.48, 0.22-1.05, P (trend) = 0.02), theaflavins (0.42, 0.19-0.93, P (trend) = 0.02), and
proanthocyanidins (0.39, 0.18-0.84, P (trend) = 0.02). In contrast, in women with higher alcohol use, intakes of
hydroxybenzoic acids (2.28, 1.16-4.49, P (trend) = 0.04),
flavonoids (2.46, 1.23-4.92, P (trend) = 0.01),
anthocyanins (2.94, 1.32-6.53, P (trend) = 0.01), catechins (2.28, 1.19-4.36, P (trend) = 0.02), and
proanthocyanidins (2.98, 1.40-6.33, P (trend) = 0.006) were associated with increased
breast cancer risk. In conclusion, this prospective study suggests that several classes of
polyphenols could potentially contribute to
breast cancer prevention among non-to-low alcohol drinkers, but some may increase
breast cancer risk among women with higher alcohol intake.