The true cost of alcohol consumption

The true cost of alcohol consumption

In the early 1990s the French scientist Serge Renaud working at Bordeaux University made the epidemiological observation that despite the relatively high dietary intake of saturated fats in France there was a relatively low incidence of coronary heart disease (CHD) – an observation labelled in the title of his research paper the “French paradox”.

It was concluded that the explanation for the paradox might be the high consumption of red wine in France, with the polyphenol resveratrol in red wine providing a protective effect.

It was a message with immense popular appeal: you can eat all the rich fatty foods you like, as long as it’s accompanied by a glass of red wine. What’s not to like?

That popularity grew after a CBS
60 Minutes interview with Renaud that promoted red wine as a protective factor against CHD. The show host concluded the programme by holding up a glass of red wine and declaring: “The explanation of the French Paradox may lie in this inviting glass.”

The show was a hit, and the following year red wine sales in the US increased by 40 percent.

 But how sound was the science? An observed correlation between drinking red wine and less CHD doesn’t establish a cause-and-effect relationship. The French people also consumed more fresh fruit, vegetables, olive oil, and fish – comparable to a Mediterranean diet. They also ate less processed foods, had a lower sugar intake, and ate smaller meal portions with less snacking between meals. All dietary factors known to be beneficial for heart health.

In addition, the French had only recently started eating unhealthy levels of saturated fats, but chronic diseases such as CHD, take decades to develop. Finally, there was also an underreporting of CHD deaths in France due to the way their health authorities defined and categorised CHD deaths.

 All these factors provided a reasonable explanation why relatively fewer CHD deaths were reported in France, without having to invoke the “health” properties of red wine.

 But catchy headlines of red wine being healthy captured the public imagination, and drove people to buy newspapers, watch TV shows and visit websites – and buy red wine. As often happens when science is popularised, the nuances and uncertainties of the research were left out, study limitations were omitted, correlations were reported as if they were causal, and the significance of the research was magnified. And even when caveats were provided, people tended to gloss over them.

 But could the resveratrol in red wine be health promoting? Red wine typically contains about three milligrams of resveratrol per litre, so you would have to consume about 80 litres of wine a day to get the equivalent dose of a resveratrol supplement, or more than 300 litres of wine a day to get the resveratrol equivalent dose used in many research studies. Claims that red wine is a useful source of resveratrol collapse when you look at the numbers – and you should always look at the numbers.

 Additionally, at the time the French paradox was proposed, there was no clear clinical evidence that resveratrol, in any form or dose, could improve cardiac health, and now, 30 years on, despite extensive research, that definitive evidence is still lacking.

The promotion of red wine as something that might be good for your health was very clever marketing, but it was never good science.

 The French paradox has been misused to promote the idea that moderate drinking can be healthy, and so has the notorious “J curve”. Many epidemiological studies have reported a J-shaped relationship between alcohol consumption and health outcomes: with all-cause mortality and ill health being least for light-to-moderate drinkers (the bottom of the “J”); with much worse health outcomes for heavier drinkers, and slightly worse health outcomes for alcohol abstainers.

 These J curve findings have been used by the alcohol industry to promote the notion that moderate drinking is healthier than abstaining – that is, moderate drinking is not just safe, it’s beneficial.

But those observational studies, which were often funded by the alcohol industry, are heavily confounded. Abstainers might indeed report poorer health than moderate drinkers, but abstainers also tend to be older people, and they might report poorer health than moderate alcohol drinkers not because alcohol is healthy but because people might abstain from drinking because they have a health problem. And people who drink lightly or moderately also tend to exercise more, have a better diet, weigh less, and smoke less.

 Recent studies that control for this confounding, including a 2023 meta-analysis of 107 observational studies involving nearly five million people, fail to find a protective health effect for light-to-moderate alcohol drinking. These findings, combined with an ever-increasing understanding of the physiological damage alcohol does, have led the World Health Organisation to proclaim that “No level of alcohol consumption is safe for our health”.

Alcohol is a Group 1 (the highest risk group)  carcinogen that is directly linked to at least seven different  cancers, with alcohol being one of the main risk factors for breast  cancer – with one in four alcohol-related breast cancers attributable to light-to-moderate drinking.

And it is estimated that every year in New Zealand, more than 1800 babies are born with foetal alcohol spectrum disorder.

Meanwhile the alcohol industry continues to aggressively target women (from pink rosé to Jane Walker whiskey), with women drinking more than ever. The marketing has been so successful that recent increases in alcohol-related liver disease and deaths are driven by women.

Individuals, and societies, will have to strike a balance between the social benefits of alcohol consumption and its costs. That starts with good science informing our decisions, and not believing a glass of wine might be good for our health.