How can alcohol damage the digestive system?
Alcohol is a drug that is not digested like food. Instead, alcohol is absorbed into the blood, which is why your blood alcohol level increases as you drink. However, each part of the digestive system is involved in absorbing, processing, or breaking down alcohol in the body.
The chemical substances of ethanol (pure alcohol) and acetaldehyde (a toxic by-product) can cause damage to cells, tissues and organs as they travel through the digestive system.
Pathway of alcohol in the body
- Mouth and throat
The mouth and throat are the first points of contact when you drink alcohol and a small amount is directly absorbed through the walls of the mouth.1
Microbes in the mouth convert some of the alcohol to acetaldehyde, a highly toxic substance. This can damage cells over time and can stop them repairing the damage, leading to cancer in the mouth and throat, including the base of the tongue and tonsils.
Even at low levels of alcohol use (up to 1 drink per day) the risk of developing cancer is significantly increased in sites where alcohol comes into direct contact with tissues in the body, including the mouth, throat, and food pipe (oesophagus).
After alcohol leaves the mouth, it flows down the oesophagus. Alcohol can directly damage the cells lining the oesophagus and is a risk factor for cancer.2,3 Drinking alcohol can also cause acid reflex, which occurs when stomach contents to come back up into the oesophagus. This can also cause damage to cells.4
About 20% of the alcohol is absorbed into the blood directly through the stomach lining. The more food you have in your stomach, the slower the alcohol is absorbed, and the longer it takes to move into your intestines. If there is no solid food in the stomach, alcohol moves down into the small intestine more easily and will pass quickly into the blood.
Alcohol can affect the stomach in different ways:
- Irritate cells in the stomach lining causing inflammation.5
- Impact stomach acid production and reduce the stomach’s ability to destroy bacteria that enter the stomach, which can allow potentially harmful bacteria to enter the upper small intestine.6
- Stimulate appetite as it increases the flow of stomach juice.
- Drinks with higher alcohol percentage can delay stomach emptying and impact digestion.7
The majority of absorption takes place in the small intestine because of the extremely large surface area.
Learn more about alcohol and nutrition.
More than 90% of alcohol is broken down by enzymes in the liver to be removed from the body. No matter how much or how little you drink, your liver can only metabolize about one standard drink per hour.
When the liver breaks down alcohol, it is converted to acetaldehyde, a highly toxic chemical and Group 1 carcinogen. The more cells in the liver try to repair the damage, the more likely they can make mistakes in their DNA, which can lead to cancer.
The pancreas makes enzymes for digestion and the hormone insulin, which helps the body turn food into energy. Alcohol can damage the pancreas, causing inflammation (pancreatitis) scarring of the pancreas. The pancreas helps digest food and control blood sugar levels. Alcohol can cause the pancreas to produce toxic substances that interferes with these functions.