Health: Why Men Can Outdrink Women

It is a familiar refrain at parties and in bars: women just can't hold their liquor. They are quicker to get giddy, and they stay drunk longer than men matching them drink for drink. For years, the difference was attributed to gross anatomy: On average, women are smaller than men, and thus alcohol gets into their tissues more rapidly. And because they carry proportionately more fat and less water in their bodies, liquor is diluted more gradually, prolonging its heady effects.

But that explanation has never been completely convincing, either to scientists or to laymen. It fails to explain fully why when men and women of the same size have identical drinks, women tend to get tipsy faster. Scientists have long wondered if there might not be a more compelling biochemical explanation for the drinking puzzle. Last week a team of Italian and American researchers offered what looks to be the answer: women have far smaller quantities of the protective enzyme alcohol dehydrogenase that breaks down alcohol in the stomach.

The enzyme is crucial in curbing intoxication. When a shot of vodka or a beer is swallowed, it travels to the stomach and then to the intestine, where it passes through the organ's wall into the bloodstream. Once there it circulates to the brain, where it finally exerts its inebriating effect. Alcohol dehydrogenase breaks down spirits in the stomach, reducing the amount of pure alcohol that enters the bloodstream about 20%; the rest is eventually metabolized by similar enzymes in the liver.

According to a study of 43 men and women reported in the New England Journal of Medicine, women possess significantly less of the active stomach enzyme. The result is that they absorb about 30% more alcohol into their bloodstreams than men do -- and voila! Taking into account the weight difference between the average man and woman, a mere 2 oz. of liquor has about the same effect on a woman as 4 oz. would on a man. Just why there is such a discrepancy remains a mystery.

The researchers made another startling discovery: men who are alcoholics have about half as much alcohol dehydrogenase as their healthy counterparts, but alcoholic women show almost no enzyme activity at all. The falloff may result from alcohol's injuring the stomach wall, where the enzyme is manufactured. Whatever the cause, "alcoholic women appear to lose all gastric protection," says Dr. Charles Lieber of Mount Sinai School of Medicine in New York City, who collaborated on the study with Dr. Mario Frezza of the University School of Medicine in Trieste, Italy. "For them to drink alcohol is the same as shooting it up directly into their veins."

Experts say this lack of protection may help explain why alcoholic women suffer more heavily from liver damage than do alcoholic men. Women may be more vulnerable to cirrhosis for another reason, says Dr. Jack Mendelson of Harvard Medical School. Studies by a team at Johns Hopkins indicate that women's livers metabolize alcohol faster than men's and thus may be more subject to wear and tear. Mendelson speculates that in female alcoholics a lack of gastric enzyme means that "their livers have to work even harder," accelerating the destruction.