Is there any harm in drinking alcohol? After all, most cultures throughout the world have traditionally consumed alcoholic beverages for thousands of years. Of these, a few alcoholic beverages have evolved into global commodities that are produced commercially on a large scale − including beer from barley, wine from grapes, and other distilled beverages.
Unfortunately, alcohol lovers all over the world need to be aware of the latest information on this topic. According to a recent extensive review of multiple research studies, alcohol consumption has been conclusively shown to be the direct cause of seven types of cancer – including those of the oropharynx, larynx, esophagus, liver, colon, rectum, and breast. Also, there is growing evidence to implicate alcohol consumption in the development of skin, prostate, and pancreatic cancer.
[Note: the oropharynx is the middle part of the throat behind the mouth and includes the back one-third of the tongue, soft palate, and side and back walls of the throat. The larynx is the hollow muscular organ that forms an air passage to the lungs and holds the vocal cords and is also known as the voice box. The esophagus, also known as the gullet or food pipe, is the tube that connects the throat to the stomach.]
Published in July this year in the scientific journal Addiction, the review study concludes that there is more than enough credible evidence to conclusively state that drinking alcoholic beverages is a direct cause of these different cancers.
This news doesn’t come as a complete surprise. In its 13th Report on Carcinogens published in 2014, the National Toxicology Program of the U.S. Department of Health and Human Services had previously listed consumption of alcoholic beverages as a known human carcinogen.
While a drinker’s risk increases relative to the amount of alcohol consumed over time and the highest risks are associated with the heaviest drinking, what is surprising – and more than a little troubling – is that even people consuming low to moderate amounts seem to be at risk.
It gets worse. This review also showed that people who smoke and drink at the same time are at even greater risk of getting cancer. And according to a 2009 study, an estimated 3.5 percent of all cancer-related deaths in the U.S. can be attributed to alcohol consumption.
How Does Drinking Alcohol Increase Cancer Risk?
Alcohol is believed to increase the risk of getting cancer in multiple ways:
- By breaking down (known as “metabolizing”) ethanol in alcoholic drinks to acetaldehyde, which is a toxic chemical and a probable human carcinogen that can damage both cellular DNA and proteins.
- By generating reactive oxygen species (ROS − chemically reactive toxic molecules that contain oxygen), which damage DNA, proteins, and fats in the body via a chemical reaction known as oxidation.
- By impairing the body’s ability to absorb and use various nutrients associated with cancer risk – such as vitamins A, the B complex vitamins such as folate, vitamin C, vitamin D, vitamin E, and carotenoids.
- By raising estrogen levels, a sex hormone linked to higher breast cancer risk.
Emerging scientific and clinical evidence shows a clear relationship between alcohol consumption and risk for the various types of cancer listed below.
Head and Neck Cancers
Alcohol consumption is now known to be a major risk factor for certain head and neck cancers, particularly cancers of the mouth (not including the lips), pharynx, and larynx. People who consume 3.5 or more drinks daily have at least 2-3 times greater risk of developing these cancers than non-drinkers.
The body breaks down alcohol thanks to an enzyme called alcohol dehydrogenase (ADH). Another enzyme, called aldehyde dehydrogenase 2 (ALDH2), further breaks down toxic acetaldehyde to nontoxic substances, which are then excreted from the body via the kidneys.
Some people, particularly those of East Asian descent, inherit a version of the ALDH2 enzyme that is defective. As a result, toxic acetaldehyde is not broken down but builds up in their bodies when they drink alcohol, resulting in unpleasant side effects including facial flushing and even heart palpitations.
Usually, most people with defective ALDH2 enzymes are unable to consume a lot of alcohol. However, some such individuals become tolerant to the effects of acetaldehyde and consume large amounts of alcohol anyway. Studies have shown that these individuals have a higher risk of alcohol-related esophageal cancer – known as esophageal “squamous cell carcinoma” – as well as of head and neck cancers. But only when they drink alcohol regularly.
Also, the risks of these cancers are much higher in such people with defective ALDH2 enzyme who both consume alcohol and also use tobacco at the same time.
Liver cancer – known scientifically as hepatocellular carcinoma – is diagnosed in half a million people worldwide every year. Alcohol consumption is an independent risk factor for, and a primary cause of, liver cancer. Too much alcohol metabolism in the liver is believed to increase liver cancer risk via excessive production of harmful reactive oxygen species (ROS), increased activity of liver cytochrome P450 enzymes, and alcohol-induced deficiency of beneficial antioxidants due to impaired absorption from the gut and a poor diet.
More than a hundred epidemiologic studies have examined the link between alcohol consumption and breast cancer risk in women. [Note: Epidemiology is the study and analysis of the patterns, causes, and effects of health and disease conditions in specific populations.]
These studies have consistently found an increased risk of breast cancer linked to higher alcohol consumption. A meta-analysis of 53 such studies (with a total of 58,000 women with breast cancer) showed that women who drank more than 3 alcoholic drinks daily had 1.5 times the risk of developing breast cancer when compared to non-drinkers. For every 10 grams of alcohol consumed daily, which is slightly less than one drink, a small (7%) increase in the risk of breast cancer was reported.
Similarly, the Million Women Study based in the U.K. examined more than 28,000 women with breast cancer. According to this study, for every additional drink consumed daily, the increase in breast cancer incidence was roughly 11 per 1,000 women up to the age of 75 years.
Alcohol consumption has been linked to a modestly increased risk of cancer of both the colon and rectum. A meta-analysis of 57 studies showed that people who regularly drank approximately 3.5 drinks daily had 1.5 times the risk of developing colorectal cancer as non-drinkers, or occasional drinkers. In other words, there is a clear association between alcohol consumption of more than one drink daily and higher colorectal cancer risk.
Numerous other studies have looked for possible links between alcohol and the risk of other cancers, such as those of the pancreas, ovary, prostate, stomach, uterus, and bladder. However, either no association has been found or the evidence for such an association is inconsistent.
Can Genetics Affect Risk of Alcohol-Related Cancers?
A person’s risk of getting alcohol-related cancers is influenced by their genes, specifically those that code for enzymes involved in breaking down alcohol − alcohol dehydrogenase (ADH) and aldehyde dehydrogenase 2 (ALDH2). For example, many individuals of Chinese, Korean, and especially Japanese descent carry a “super-active” form of the enzyme ADH which rapidly converts alcohol to toxic acetaldehyde. As a result, when these people drink alcohol, acetaldehyde levels build up in their bodies, increasing their risk of pancreatic cancer.
Similarly, people with deﬁcient ALDH2 face much higher risks of developing esophageal cancer after alcohol consumption than those with a fully active enzyme.
Tips to Lower Your Cancer Risk From Drinking Alcohol
While abstaining from alcohol is the safest bet, here are some tips to lower your alcohol-related cancer risk:
- Have some alcohol-free days every week to cut down on the total amount of alcohol you consume
- Swap every second or every third alcoholic drink for a healthier beverage such as water
- Choose smaller servings (e.g. get singles not doubles and use smaller glasses)
- Substitute with less alcoholic versions of drinks
- Don’t keep a stock of alcohol at home
Promisingly, there’s some evidence to suggest that drinkers who give up alcohol can reverse their risk of laryngeal, pharyngeal, and liver cancer. Their risk stays reduced the longer they avoided alcohol.
On the other hand, in studies that have focused on head and neck cancers and on esophageal cancer, stopping alcohol consumption does not automatically mean lowered cancer risk right away. Instead, it may take years for cancer risk to come down again.
For example, a pooled analysis of 13 case-control studies of cancer of the mouth, throat, and pharynx combined found that alcohol-associated cancer risk did not begin to drop until at least 10 years after stopping alcohol consumption. Even 16 years after they stopped drinking alcohol, the risk of cancer was still higher for ex-drinkers than for people who had never consumed alcohol.
It is true that certain substances in red wine, such as resveratrol, have been reported to have beneficial effects for health, especially when it comes to cardiovascular disease. However, clinical trials in humans have so far not provided credible evidence that resveratrol is effective in preventing or treating cancer. Also, resveratrol can be more easily obtained from grapes, raspberries, and resveratrol supplements – all of which are much healthier options than red wine.