What enzymes break down alcohol in the liver?

Which liver enzymes break down alcohol?

The main alcohol-processing enzymes in the liver are:

- Alcohol dehydrogenase (ADH): Converts ethanol (drinking alcohol) into acetaldehyde.
- Aldehyde dehydrogenase (ALDH): Converts acetaldehyde into acetate, which is then further metabolized in the body.

What happens to alcohol before these enzymes work?

When alcohol is present, liver cells also use oxidation pathways to handle it. One commonly discussed secondary route is:
- CYP2E1 (a cytochrome P450 enzyme): Helps break down ethanol into acetaldehyde, especially when alcohol intake is heavy or chronic.

Why do these enzymes matter for liver injury?

A key reason these enzymes are important is that acetaldehyde (the intermediate product) is toxic. ADH and ALDH determine how much acetaldehyde is produced and how quickly it’s cleared, which affects stress on liver cells.

What changes if someone drinks heavily or chronically?

With heavy or long-term drinking, the balance between these enzymes can shift. CYP2E1 activity often increases in chronic alcohol use, which can increase oxidative stress while alcohol is being metabolized.