If a woman and a man drink identical glasses of wine with the same meal, the former is likely to have a higher blood level of alcohol, and for a longer time.
This means her tissues are exposed to more alcohol per drink than a man's.
The researchers suggest that too much alcohol is bad for a woman's heart and arteries, and earlier work shows it can be hazardous to breast tissue too.
The current guidelines recommend one to two drinks a day for men and no more than one a day for women.
The study appears in the October 2008 issue of the Harvard Heart Letter.