Moderate alcohol intake is defined as no more than two drinks a day for a man, and one for a woman. Why the difference?
Women end up with a higher blood level of alcohol and thus become more impaired than men from the same amount of alcohol. For one thing, they tend to be smaller and have proportionately less body water and more fat than men the same size (alcohol is diluted in body water and not absorbed in fat). And the stomach enzyme that breaks down alcohol before it reaches the bloodstream is less active in women. This allows more alcohol to enter the blood.
Thus, women are more likely to develop damage to the liver, heart muscle, and brain at lower levels of alcohol intake. Alcohol also increases the risk of breast cancer, and higher intakes can weaken bone.
Though women are less likely than men to drive after drinking, they have a higher risk of having a fatal crash at a given blood alcohol concentration. Studies suggest that alcohol has a greater effect on driving skills in women.
Keep in mind: Older women face a double alcohol whammy, since older bodies don’t process alcohol well. As a result, a given amount of alcohol leads to higher blood alcohol concentrations and more adverse effects. In addition, alcohol doesn’t mix well with many drugs older people take. So for older women, moderation is less than a drink a day. Still, even half a drink a day can provide heart benefits, some research suggests.