In summary, daily consumption of 15 g of ethanol/day has no effect on serum estrogen levels in postmenopausal women, and the prediction based on the alcohol-estrogen mechanism is not confirmed by either the Allen et al or Li et al studies. Furthermore, a recent meta-analysis also found no effect of drinking less than 19 g of ethanol/day on estradiol levels (Key et al., 2011). Therefore, the observed relationship between daily consumption of 10 g of alcohol and breast cancer risk in postmenopausal women cannot be explained by a mechanism involving increased serum estrogen levels.
