Moderate drinking doesn't mean you'll live longer, Canadian scientists find: What to know about alcohol and cancer risk

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New research from Canadian scientists suggests numerous studies don't accurately portray the effects of moderate drinking. While some messages may indicate a small daily dose of alcohol might be better for a longer life, new analysis challenges this idea and claims research has been flawed.

Experts in Canada analyzed 107 published studies on people's drinking habits and their lifespans, according to the Guardian. They found in most cases, drinkers were compared with people who abstained from drinking alcohol, or consumed very small amounts. However, several studies didn't take into account that some of those people had changed their drinking habits due to being sick.

Ultimately, this brought the group's average health down. In turn, multiple studies likely incorrectly suggest light to moderate drinkers look better than they really are when comparing the groups.

Many studies indicate death rates are lowest among people who drink a little, and the Canadian team's analysis suggested people who have one drink a week up to two a day had a 14 per cent lower risk of dying over the study period compared with abstainers. However, the best-quality studies — which made sure to include younger people as well as separate abstainers from former and occasional drinkers — didn't show that light to moderate drinkers lived longer.

"The great majority of previous studies compare drinkers with an increasingly unhealthy group of people who currently abstain or drink very little," Canadian scientist and first author on the study Tim Stockwell tells the Guardian. "We know people give up or cut down on drinking when they become unwell and frailer with age. The most biased studies included many people who had stopped or cut down their drinking for health reasons in the comparison group, so making people well enough to continue drinking appear even healthier."

The Canadian Centre on Substance Use and Addiction's latest Guidance on Alcohol and Health, updated in January 2023, indicates no amount of alcohol is safe to consume. Moreover, having more than two drinks per week is considered risky. The guidelines also indicate having three to six drinks a week increases the risk of developing certain cancers, such as colorectal and breast cancers. More than seven drinks a week also ups your risk of heart attack and stroke.

Studies have shown cancer is linked to a variety of risk factors, such as genetics, diet and exercise. However, lifestyle factors also play a role, where drinking alcohol has been linked to multiple types of cancer including breast, colon, esophageal, liver and mouth.

How certain foods and beverages are linked to cancer

Substances known as carcinogens have been scientifically proven to cause or contribute to the development of cancer. Carcinogens can be found in our environment, in chemicals and substances we come in contact with, and are found in the food and drinks we consume.

Certain foods like red meat and processed meats are considered carcinogenic. Additionally, sugary drinks have been indirectly linked to cancer because they contribute to weight gain, which is a risk factor for the condition. Alcohol is considered a group one carcinogen and a significant contributor to the development of cancer.

Five types of cancer linked to alcohol consumption

Below are five common cancers that have been scientifically linked to drinking alcohol.

1. Breast cancer

The link between alcohol consumption and breast cancer has not been unanimously defined. However, the leading theory is that alcohol consumption contributes to estrogen circulation in women who have not yet undergone menopause, which is necessary for breast cancer to develop.

According to Cancer Care Ontario, women who have at least two alcoholic drinks per day increase their risk of developing breast cancer by up to 31 per cent compared to individuals who don't drink. This risk is lowered to a 10 per cent increase in women who only drink one alcoholic beverage daily.

2. Colon cancer

Alcohol contributes to the development of colon cancer through the creation of polyps. This happens when your body processes alcohol, which can damage colon cell DNA.

In 2020, a study by the World Health Organization's International Agency for Research on Cancer found that alcohol consumption was linked to 20 per cent of new colon cancer cases in Canada.

3. Esophageal cancer

Drinking alcohol can dramatically increase your risk of developing esophageal cancer. A study from McGill University found that heavy drinkers increased their risk of esophageal cancer by seven times compared to non-drinkers. The risk of developing esophageal cancer increases when combined with smoking tobacco.

4. Liver cancer

People are encouraged to avoid alcohol for their liver health. However, they're often unaware that drinking can contribute to alcohol-induced liver cancer and disease.

However, the link between alcohol and liver cancer has been defined as "probable" by the American Institute for Cancer Research and the World Cancer Research Fund because liver cirrhosis typically encourages people to stop drinking.

5. Mouth and throat cancers

Alcohol consumption increases the risk of developing mouth and throat cancers. Aside from altering your DNA and affecting your hormonal balance, alcohol can alter your cellular makeup in this area of the body. As a result, the cells of your mouth and throat may be more permeable to potential carcinogens.

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