Wednesday, 17 April, 2024
HomeHarm ReductionWhy science no longer supports drinking alcohol in moderation

Why science no longer supports drinking alcohol in moderation

In 1991, the host of the news programme 60 Minutes in the United States went to France in search of an answer: why were the French, with a diet known for being high in fat, less likely to die from heart disease than the Americans?

A French scientist told him that drinking wine in moderation could explain this.

But today, writes Liesl Pretorius for Bkekisisa, enthusiasm for drinking any kind of alcohol in moderation is waning.

A podcast episode in which Stanford neuroscientist Andrew Huberman described alcohol – even in moderation – as “poison”, was among the most-shared episodes on Apple Podcasts in South Africa last year.

Also in 2023, authors from the World Health Organisation wrote in The Lancet Public Health that “no safe amount of alcohol consumption for cancers and health can be established”.

Their view mirrored shifts in some organisations’ guidelines for alcohol use over the past few years.

For example, the American Cancer Society (ACS) used to say that women should cap alcohol use at one drink a day and men, at two. (A drink was defined as 355ml of beer, 148ml of wine or 44ml of hard liquor.) But its 2020 guidelines for cancer prevention say it’s “best not to drink alcohol” at all.

The reason for the change, said Marjorie McCullough, the ACS’ senior scientific director of epidemiology research, is that the evidence about the links between alcohol consumption and cancer has evolved, with research showing that drinking even small amounts of alcohol could up someone’s chance for developing some types of cancer, including breast cancer.

Until about the middle of last year, the Heart and Stroke Foundation South Africa’s website advised that those who drink, do so in moderation – up to one drink per day for women and two for men. (In this case, one drink is 340ml of beer, 120ml of wine, 60ml of sherry or 25ml of spirits.)

Head of the Foundation Pamela Naidoo referred Bhekisisa to a World Heart Federation policy brief for updated recommendations that say there’s “no safe level of alcohol consumption”.

Alcohol and the heart: it’s complicated

The idea that moderate drinking – around two drinks a day or less – is good for the heart had gained momentum by the 1990s.

Some scientists believed moderate drinkers were less likely to have heart attacks than non-drinkers, partly because alcohol upped their “good” cholesterol levels.

Cholesterol molecules made up of high-density fat-bound proteins are said to be of a “good” type because they help to carry cholesterol with a low density out of the blood and back to the liver, which prevents the waxy, fatty substance from building up in someone’s arteries and so restrict blood flow, which could cause a heart attack.

However, research increasingly shows that the possible protective effects of drinking a little alcohol have been exaggerated.

Jürgen Rehm, a senior scientist at the Centre for Addiction and Mental Health in Toronto, pointed to a 2023 study finding no evidence among Chinese men that regularly drinking small amounts is heart-healthy.

In fact, he said, “these (beneficial) effects are over-emphasised because of problematic methodological designs and most of the research coming from (only) a few countries”.

One reason why the once-thought benefits of alcohol now seem to be smaller is that some studies made teetotallers look worse off than they were. This happened because abstainers were lumped together with sick people who used to drink, known as “sick quitters”.

Alcohol use might, therefore, not adequately explain why moderate drinkers are less likely to have heart attacks than non-drinkers.

Causing cancer since (at least) the 1980s

The link between alcohol and cancer is less contentious.

Alcohol use can make it more likely that someone could develop one of at least seven types of cancer – mostly of organs or tissues along the digestive tract, such as the mouth, throat, voice box, oesophagus, liver and colon – and also breast cancer in women.

One way in which this happens is that ethanol (the type of alcohol that gives drinks their zing) breaks down to a chemical called acetaldehyde, which damages DNA.

A 2017 study published in the European Journal of Public Health calculated that in that year, there could have been 23 000 fewer new cancer cases in the European Union if people who drank up to two drinks a day did not drink at all. (A drink was defined as about 300ml of beer, 100ml of wine or a shot of spirits.)

Most of the cancer cases linked to what the authors called light to moderate drinking were breast cancers. Rehm, the co-author of that study, told Bhekisisa breast cancer would probably make up a large share of cases caused by light to moderate alcohol use in other parts of the world too, including in Africa.

Even though the International Agency for Research on Cancer found, more than 30 years ago already, that alcohol can cause cancer, experts say few people are aware of the link.

According to McCullough, part of the problem is that some doctors aren’t aware of this either and that “there haven’t been broad public health campaigns to raise awareness”.

(How much) should we drink?

A 2022 analysis of data from the 2020 Global Burden of Diseases (GBD) Study cautions that a one-size-fits-all set of guidelines for alcohol use won’t work. Instead, things like people’s age and where they live should be factored in.

Broadly speaking, the authors suggest that people between 15 and 39 should avoid alcohol because they are more likely to get injured after drinking – for example, from being involved in car accidents or fights.

For older people, who are more likely to suffer from alcohol-linked diseases such as heart disease or cancer, it’s not as simple. For one, small amounts of alcohol could lower the risk of some diseases (like coronary heart disease) but increase others (for example, breast cancer).

This is where location comes in. The diseases that typically occur in a country or region influence the amount of alcohol considered safe inhabitants.

Here it’s important to know what disability-adjusted life years or DALYs are: one DALY represents the loss of one year of full health because of disability or death.

Dana Bryazka, lead author of the GBD 2020 alcohol analysis and researcher at the Institute for Health Metrics and Evaluation at the University of Washington’s school of medicine, said that in some places, a disease like tuberculosis (TB) might make up a big share of total DALYs.

And because heavy drinking can make it easier for someone to develop TB because it weakens the immune system, the amount of alcohol considered safe for those adults would be lower than in a place where coronary heart disease makes up a big part of the DALYs.

Charles Parry, a substance abuse epidemiologist at the South African Medical Research Council who was part of the recent GBD analysis, says older people shouldn’t assume that drinking a little will benefit them.

“GBD results refer to population health rather than individual health, so it’s risky if people ‘blindly’ (apply) the population-level findings to themselves.”

Putting a cap on the tap

South Africa doesn’t have national drinking guidelines “because we don’t recommend alcohol intake”, said the Health Department’s spokesperson Foster Mohale. (The country’s food-based dietary guidelines used to recommend drinking “sensibly”, but this guideline was dropped in 2012.)

One of the countries that recently updated its drinking guidelines is Canada. Published in January 2023 and funded by the government, it recommends much lower alcohol use than in 2011.

Back then, women were urged to drink no more than 10 drinks a week and men to limit their weekly drinking to 15. (A drink was set at 341ml of beer or cider, 142ml of wine or 43ml of spirits.)

The new guidelines, though, say people should have only two drinks a week, to limit the chance of harm. At three to six drinks weekly, someone’s risk of developing cancer increases, thereby putting them at “moderate risk”.

Put differently, said Peter Butt, clinical associate professor at the University of Saskatchewan’s college of medicine and co-chair of the project to update Canada’s drinking guidelines: if a Canadian has up to two drinks a week, the chances of alcohol use causing early death are one in 1 000. If they have up to six drinks, the chances shoot up to 1 in 100.

Beyond this limit, “increasing risk (is) conferred by every additional drink”, according to the guidelines.

The drop in the number of drinks per week has been controversial, though.

Dan Malleck, a professor of health sciences at Brock University, told The Guardian: “We aren’t just machines with inputs and output of chemicals or nutrition.”

Overall, drinking less is better for your health.

Parry’s advice is to consider your health and history when deciding whether to keep drinking. “For example, do you have a family history of cancer? Where do you drink – at home or do you walk to a pub or shebeen, which might put you at greater risk of injury? Do you have high blood pressure? Is it well managed?”

If you don’t drink, experts say it’s not a good idea to start. As Butt notes: “We can’t choose what organ, or what aspect of a system, will be affected by the alcohol we consume. The net whole-body effect [of alcohol] is negative.”

WHF-Policy-Brief-Alcohol

 

The Lancet article – Health and cancer risks associated with low levels of alcohol consumption (Open access)

 

Nature Medicine article – Alcohol consumption and risks of more than 200 diseases in Chinese men (Open access)

 

European Journal of Public Health article – Estimation of cancers caused by light to moderate alcohol consumption in the European Union (Open access)

 

The Lancet article – Population-level risks of alcohol consumption by amount, geography, age, sex, and year: a systematic analysis for the Global Burden of Disease Study 2020 (Open access)

 

Bhekisisa article – Is it cheers to saying cheers? Why science says no to drinking alcohol (Creative Commons Licence)

 

See more from MedicalBrief archives:

 

Lowering intake, quitting alcohol, cuts oral cancer risk

 

UK-China genetic study confirms that alcohol is a direct cause of cancer

 

Alcohol consumption linked to 4% of global cancer cases – WHO study

 

Alcohol consumption associated with nearly 5% of US cancer cases

 

Cutting back, quitting alcohol, may reverse brain shrinkage: US study

 

Why alcohol-free days are important

 

 

 

 

 

 

 

 

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