How does alcohol cause cancer?
There are many possible explanations for how alcohol causes cancer. It is likely that different cancers are caused in different ways.
Here are the most likely theories:
In our bodies, alcohol (ethanol) is converted into a toxic chemical called acetaldehyde. It can cause cancer by damaging DNA and stopping our cells from repairing this damage. The International Agency for Research on Cancer have classified acetaldehyde formed as a result of drinking alcohol as being a cause of cancer, along with alcohol itself.
Acetaldehyde also causes liver cells to grow faster than normal. These regenerating cells are more likely to pick up changes in their genes that could lead to cancer.
Ethanol is broken down mainly by the liver, but lots of other cell types can do this as well. Some of the bacteria that live in our mouths and the linings of our guts are also able to convert ethanol into acetaldehyde.
Oestrogen and other hormones
Alcohol can increase the levels of some hormones, such as oestrogen. Hormones act as messengers in the body, giving our cells instructions such as when to divide. Unusually high levels of oestrogen increase the risk of breast cancer.
Drinking lots of alcohol can damage the cells of the liver, causing a disease called cirrhosis. Cirrhosis can make you more likely to develop liver cancer.
Alcohol and other carcinogens
Alcohol makes it easier for the tissues of the mouth and throat to absorb the cancer-causing chemicals in tobacco. This is one reason why people who drink and smoke multiply the damage they receive and have especially high risks of cancer.
Folate is an important vitamin that helps our cells produce new DNA correctly. People who drink alcohol tend to have lower levels of folate in their blood and some studies have found that some cancers are more common in people with low folate levels. But at the moment it isn't clear if alcohol does cause cancer in this way, or whether the amount of folate people get in their diet affects the risk from alcohol.
Highly reactive by-products
Alcohol can cause highly reactive molecules, called Reactive Oxygen Species (ROS), to be produced in our cells. These molecules can damage the DNA, which could cause cancer to develop.
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