Allegrini 2018

“There are no safe levels of alcohol consumption”: indisputable or not provable premise?

The results of a study that three Italian scholars conducted have become a debate, revealing the structural limits of many studies on alcohol & health
A toast with wine (credits: Unsplash)

The relationship between alcohol consumption and health is one of the great, almost never-ending themes about which discussions and public debate are always very lively. The WHO guidelines, and the Beating Cancer Plan of the European Union’s objectives aim towards a global reduction in consumption, and the current global economic situation is accelerating the process, while the reasons are very different from a clear and conscious health choice. The background is comparing not only the two points of view, but also two very distinct and distant scientific approaches, which the paper, “How Much is Too Much? A Methodological Investigation of the Literature on Alcohol Consumption” (here) has brought back to popularity. The paper was edited by Italian researchers Stefano Castriota and Paolo Frumento of the University of Pisa, and Francesco Suppressa of the University of Siena, who analyzed dozens of studies and 6.763 medical abstracts underlining the many methodological problems and limitations.

These are observational studies, which very often, the researchers concluded, have omitted important variables, or there are calculation errors on real alcohol consumption, while in others linear models have been used instead of non-linear models. These are methodology limitations that result in the impossibility of unequivocally maintaining that “there are no safe levels of alcohol consumption”. The conclusion overturns the table on which WHO policies have been based for years, supported, actually, by rather limited scientific literature, including the now famous, “Alcohol use and burden for 195 countries and territories, 1990-2016”, which stands out. It is a systematic analysis conducted for the Global Burden of Disease Study”, published by “The Lancet” in 2018, signed by doctor Max G Griswold, involving hundreds of other scholars from all over the world.

Another criticism is that the conclusions of the studies are polarized between limited protective effects of moderate consumption and strong negative effects linked to its abuse. Researchers are often much more likely to cite other studies that reach the same conclusions. Furthermore, we must also deal with an important distortion in publication because it is seven times easier to publish statistically significant results compared to null (non-significant) results in scientific journals. However, the ratio between studies that indicate a significance level less than 5%, and those that exceed that percentage is growing. This bias has encouraged researchers, especially in medicine, to force results to become significant, creating false positives while helping to distort the view of public authorities.

Obviously, nobody wants to doubt the harmfulness of certain consumption habits, which lead to abuse and which every year cause, directly or indirectly, close to 3 million deaths all over the world. This being the case, though, it is more and more difficult to continue maintaining that the right path is total abstention from consuming alcohol. Instead, bringing back to popularity the concept of moderate consumption, which is the basis of the Mediterranean Diet, as well as in the guidelines of many countries, and up until 2010 was one of the recommendations of American dietitians who acknowledged moderate alcohol consumption as having a positive impact on limiting the mortality rate from all causes.

The recommendations, instead, disappeared in 2015, and were gradually abandoned by everyone, due to the enormous discrepancy, from Country to Country, regarding the concept of moderation. According to a study in 2016, 37 countries out of 75 considered, had adopted a precise definition of the “standard glass”, or the “standard dose”. In general, it was 10 grams of pure ethanol, but in Countries such as Iceland and Ireland, it was 8 grams, while in Austria it was 20 grams. Likewise, there was no consensus on the definition of “moderate consumption”, which varies from 10 to 42 grams of ethanol per day for a woman, and from 10 to 56 grams per day for a man.

Up until a few years ago, the WHO had established the limit of moderate consumption to two standard glasses of wine per day, and at least two days of abstinence per week. Then, the WHO chose a different path, simplifying the core message of its policies to the bare minimum, and also avoiding distinctions, which are important, but impossible to make for each single consumer. Therefore, now the line of abstention is winning. It is very difficult to accept this line, mainly because of the many limitations as the studies that support it have revealed. There is another aspect, namely the economic importance of a supply chain which, globally, is worth about 500 billion euros, not taking into consideration the hotel and restaurant sectors.

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