What Happens When We Drink Alcohol - Part II

Last week, we talked about many of the adverse effects of alcohol on our bodies. Today we will talk about more adverse effects of alcohol, including the various cancers that are associated with alcohol use as well as how alcohol affects fertility and pregnancy.

What is the evidence regarding alcohol and cancer risk?

There is strong evidence that drinking alcohol can cause several types of cancer. The National Toxicology Program of the US Department of Health and Human Services lists consumption of alcoholic beverages as a known human carcinogen (a substance that causes cancer).

The evidence from research indicates that the more alcohol a person drinks, the higher their risk of developing a cancer that is associated with alcohol. This is particularly true when a person is drinking regularly over time. Even people who have no more than one drink per day have a modestly increased risk of some cancers.

Research from 2009 estimated that 3.5% of cancer deaths in the US were alcohol related.

How does alcohol increase the risk of cancer?

There are several ways that researchers believe alcohol increases cancer risk, including:

• The metabolism of alcohol produces a toxic chemical called acetaldehyde. This chemical can damage DNA as well as proteins within cells.
• Alcohol metabolism generates chemically reactive molecules that contain oxygen. These molecules can damage DNA, proteins, and fats within the body.
• Alcohol reduces the body's ability to breakdown and absorb a variety of nutrients that affect cancer risk.
• Alcohol use increases blood levels of estrogen (in both women and men), which can increase the risk of certain cancers.
• Alcoholic beverages can sometimes contain small amounts of one or more contaminants that increase the risk of cancer.

What cancers are associated with alcohol intake?

Here are the cancers that have been associated with alcohol use:

Head and neck cancer - Includes cancers in the mouth, throat, and larynx

Esophageal cancer - Especially squamous cell carcinoma

Liver Cancer - Higher risk after alcoholic liver disease develops

Breast Cancer - Research indicates that women who consume one alcoholic drink per day have a 5-9 percent higher chance of developing breast cancer, and the risk increases by approximately 7-12% for every additional 10 grams of alcohol drunk per day.

Colorectal cancer - Moderate to heavy alcohol intake is associated with up to a 1.5-fold increased risk of developing colorectal cancer, compared to no alcohol intake.

Evidence is not definitive yet but is accumulating to suggest that alcohol intake is associated with increased risks of melanoma, prostate cancer, and pancreatic cancers.

How does alcohol affect fertility?

Alcohol use can decrease fertility. This can happen in 2 ways.

• Studies suggest that even light drinking in women can make them less likely to conceive.
• Heavy drinking in men can lower both the quantity and quality of sperm.

If you're trying to get pregnant, avoiding alcohol intake is the best advice.

Why is alcohol dangerous during pregnancy?

Alcohol in the mother's blood passes to the baby. There is no known safe amount of alcohol use during pregnancy. There is also no safe time during pregnancy for alcohol use. This makes it important for women to avoid alcohol while they are trying to get pregnant for two reasons.

Alcohol use during pregnancy can cause:

• Miscarriage
• Stillbirth
• Fetal alcohol syndrome - A condition causing a range of lifelong physical, behavioral, and intellectual disabilities.

We can talk further about fetal alcohol syndrome at another time.

Next week, we will wrap up our series with the effects of alcohol on the liver.

If you have any questions about the effects of alcohol, please log into your account and send us your question. We are here to help.

Dr. Anita Bennett MD - Health Tip Content Editor