opinion / To your good health: In vino sanitas


The WHO “no safe level” dogma: A tale of weak associations and methodological issues


Dr Erik Skovenborg A


national survey in France in 1954 showed that the French, as a nation, regarded a daily intake of


nearly 2 liters (approx 2 quarts) of wine as not being harmful either to the body or to the mind of a working man.1


By contrast,


in a news release in January 2023, the World Health Organization warned that “No level of alcohol consumption is safe for our health.”2


“We cannot talk about


a so-called safe level of alcohol use. It doesn’t matter how much you drink—the risk to the drinker’s health starts from the first drop of any alcoholic beverage,” Dr Carina Ferreira-Borges wrote. “The only thing that we can say for sure is that the more you drink, the more harmful it is—or, in other words, the less you drink, the safer it is.” The “no safe level” dogma is bad news indeed for today’s wine drinkers who appreciate a glass or two with their meal and who consider themselves to be sensible drinkers. Should the many people who derive pleasure from a glass of wine become abstainers? Or is the absolute risk of light or moderate drinking so small that it is perfectly reasonable to decide that the quality of life gained from enjoyment of wine is greater than the potential harms it entails?


Solid evidence or weak associations? “Alcohol is a toxic, psychoactive, and dependence-producing substance and has been classified as a Group 1 carcinogen by the International Agency for Research on Cancer decades ago—this is the highest risk group, which also includes asbestos, radiation and tobacco.”2


As a matter of fact,


however, group 1 carcinogens are not “the highest-risk group” but a group of substances where there is enough evidence to conclude that they can cause cancer in humans. The list of group 1 carcinogens also includes, for example, processed meat, salted fish, wood dust, and ambient air pollution.


90 | THE WORLD OF FINE WINE | ISSUE 87 | 2025


A recent meta-analysis found that drinking up to 15g alcohol per day is not associated with the incidence of the 20 most common cancer types in the Western world, and the association was negative for some cancers


“Alcohol causes at least seven


types of cancer, including the most common cancer types, such as bowel cancer and female breast cancer. The risk of developing cancer increases substantially the more alcohol is consumed. However, latest available data indicate that half of all alcohol- attributable cancers in the WHO European Region are caused by ‘light’ and ‘moderate’ alcohol consumption— less than 1.5 liters of wine or less than 3.5 liters of beer or less than 450 milliliters of spirits per week.”2 Rovira & Rehm found, however, that light to moderate drinking levels of alcohol (<20g alcohol/day) accounted for 2.3% of all cases of the seven alcohol-related cancer types. Almost half of these cases were female breast cancers. More than one third of the cancer cases due to light to moderate drinking resulted from a light drinking level of <1 standard drink per day.3 Conversely, a recent meta-analysis


found that drinking up to 15g alcohol per day is not associated with the incidence of the 20 most common cancer types in the Western world, in contrast to higher consumption. It was noteworthy that the association with light and moderate alcohol consumption was negative for cancers such as (non)-Hodgkin lymphoma, leukemia, and lung and renal cancer.4


Serious methodological issues: heterogeneity


A positive association between alcoholic- beverage consumption and risk of several types of cancer is supported by more than 100 epidemiological studies. The evidence base, however, shares a number of methodological issues—such as study heterogeneity, the understudied role of different drinking patterns, and underreporting of various magnitude. Study heterogeneity delineates the variability in study outcomes that goes beyond what could be explained due to chance or measurement error. Differences between results of studies may be so high that calculation of an average effect size in a meta-analysis would make too little sense.5 A brand-new evidence synthesis of 122 systematic reviews and meta- analyses of causes and risk factors of breast cancer—“What Do We know for Sure?”—found that many of the included studies investigating the same topics had confusing or conflicting results. Three systematic reviews of alcohol use and breast cancer were included in this evidence synthesis with inconsistent findings. The conclusions varied from “there is an association” between alcohol consumption and breast cancer risk, to “the association remains insufficient”; from “high intake of wine contributes” to breast cancer risk, to “protection is exerted with low doses of wine.” Although one of these meta-analyses concluded with an association with an effect size of 1.28, the result did not qualify for the “top list” of important findings because of high heterogeneity.6


Patterns of alcohol consumption The volumes of alcohol intake listed as “light or moderate consumption” does not represent a drinking pattern but is a categorization of drinking level by quantity. Most studies categorize light alcohol consumption as  1 drink (10g)/ day, but the “10g/day category” is an


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