Background: The associations of drinking frequency and quantity with risk of myocardial infarction have not been studied among women, and the degree to which specific risk factors mediate the inverse association of drinking frequency with risk of myocardial infarction is uncertain.
Methods and results: We conducted nested case-control studies of 32,826 women enrolled in the Nurses Health Study followed up from 1990 to 1998 and 18,225 men enrolled in the Health Professionals Follow-Up Study followed up from 1994 to 2000. A total of 249 women and 266 men with incident myocardial infarction were matched on age, smoking, and date of entry to 498 female and 532 male control participants. We determined the risk of myocardial infarction related to frequency and quantity of alcohol intake and the change in risk before and after adjustment for putative cardiovascular risk factors. Among both women and men, drinking frequency tended to be associated with lower risk of myocardial infarction, with the lowest risks among those who drank 3 to 7 days per week. Further adjustment for levels of high-density lipoprotein cholesterol, hemoglobin A(1c), and fibrinogen attenuated 75% of the association of frequent drinking with risk among women and fully attenuated the association among men.
Conclusions: Alcohol intake at least 3 to 4 days per week is associated with a lower risk of myocardial infarction among women and men, an association apparently attributable to the relationship of alcohol with HDL cholesterol, fibrinogen, and hemoglobin A(1c). Because the effects of alcohol on HDL cholesterol, fibrinogen, and insulin sensitivity have been confirmed in randomized trials, our findings support the hypothesis that the inverse relation of alcohol use and myocardial infarction is causal.