Metabolism - Alcohol
The liver converts alcohol into a reactive molecule called acetaldehyde and highly reactive oxygen-containing molecules known as oxygen radicals by using an enzyme, alcohol dehydrogenase.
The acetaldehyde may play a role in alcohol-related liver damage. Another enzyme, aldehyde dehydrogenase (ALDH) breaks down acetaldehyde into acetate. The acetate is further broken down into carbon dioxide and water.
Some people either lack the ALDH enzyme or it doesn't function well - in such cases symptoms include flushing of the face, hot sensations, nausea and palpitations. This molecule is also responsible for hangovers.