Alcohol dehydrogenase (ADH1) is an enzyme that degrades alcohol in the human body. However, such an enzyme also plays a role in the final step of alcoholic fermentation by yeast, during which alcohol is produced. Zinc plays an important role in the enzyme.
The amount of ADH1 enzyme in the body varies from person to person and determines how quickly drunk alcohol is degraded in the body. How much alcohol a person can tolerate depends on many factors, such as the habit of handling high levels of alcohol. In general, East Asians, Native Americans, and Aborigines of Australia tend to have low levels of ADH in their bodies, and women less than men.