More than 90% of absorbed alcohol is metabolized, oxidized and eliminated by the liver; 2 to 5% is excreted without changes in urine, sweat and breathing. The first step in alcohol metabolism is the oxidation of acetaldehyde by the enzyme called alcohol dehydrogenase (ADH). This enzyme converts alcohol to acetaldehyde which, even in small concentrations, is toxic to the body. The enzyme aldehyde dehydrogenase (ALDH), in turn, converts acetaldehyde to acetate. Most of the acetate produced reaches other parts of the body through the bloodstream where it participates in other metabolic cycles.
