What, exactly, is a standard drink? Researchers highlight variations in alcohol consumption guidelines

The World Health Organization defines a standard drink as 10g of pure ethanol, and both men and women are advised not to exceed two drinks a day.

Yet the definition of a ‘standard’ drink differs substantially between nations – ranging from 8g to 20g, according to a study published in the journal Addiction.

Those working with drinking guidelines across national boundaries should be sensitive to substantial variations in ‘standard’ drink definitions and low-risk drinking guidelines, advise researchers.

A not-so-standard drink

The study looked at a pool of 75 countries that could be expected to have a definition of a ‘standard’ drink and low-risk drinking guidelines. Only 37 countries (less than 50%) provided a definition that was either publicly available or communicated to the researchers.

The size of a ‘standard’ drink varies by 250%, from 8g pure ethanol in Iceland and the UK, to 20g for a drink in Austria.

An 8g drink is equivalent to 250 ml / 8.45 US fluid ounces of 4% beer, 76 ml / 2.57 oz of 13% wine, or 25 ml / 0.85 oz of 40% spirits.

“Although the WHO suggested that a standard drink size of 10g of pure ethanol is clearly the modal definition in use around the world, only half of countries use it specifically or present a ranged definition that includes it,” wrote the researchers in the study.

Those countries that do use a 10g pure ethanol definition include Australia, New Zealand, China, France, Germany, India, and Singapore.  

Meanwhile, some countries define a drink more precisely than others: in Luxembourg a standard drink is 12.8g, whereas in Switzerland the standard is more loosely defined as 10-12g.

Drinking guidelines

There are other variations in national guidelines.

“Almost all countries with standard drink definitions (and, indeed, some without any, such as Belize, Trinidad and Tobago) recommend abstinence from alcohol during pregnancy and/or during breastfeeding,” the researchers explain.

“Some countries specify a higher drink limit for ‘special occasions’ (e.g. Australia, Canada, Denmark, Fiji, France, Mexico, New Zealand, Poland and the UK) and many guidelines recommend abstinence from alcohol for 1–3 days per week; examples include Canada, Chile, Estonia, Germany and New Zealand”.

And even set guidelines for a standard drink need to be considered in context, say the researchers.

“The data from several countries merit elaboration. Austria has a domestic standard drink size of 20g, but the health ministry's educational materials also present parallel low-risk drinking guidelines assuming a smaller drink definition that is more similar to that in other countries (8g),” continues the study.

“South Africa's government disseminates recommendations on the number of glasses of beer and wine per day, but does not provide standard measures of these drinks.

“Malta and Malaysia define a standard drink but do not have specific low-risk consumption guidelines, whereas Japan has low-risk consumption guidelines in grams of pure ethanol but does not define a standard drink.

“The US government, rather confusingly, has guidelines for low-risk drinking, yet also has a separate, lower guideline for ‘moderate drinking’ (up to 14 g a day for women and 28 g a day for men).”

In Australia, Grenada, Portugal and South Africa, low-risk drinking guidelines are the same for men and women.

Evolving guidelines

So why is the differentiation between standard drink sizes significant?

To start with, public health researchers and anyone working with drinking guidelines across country borders need to appreciate they may not be comparing like with like.

“Caution should be exercised when attempting to translate alcohol findings across national borders – for example, when reading a study of ‘low-risk drinking’ published in a country other than one's own,” advise the researchers.

“Although the 10g of pure ethanol per standard drink definition is prevalent, assuming its universality would be an error as often as it would be correct.”

The researchers also hope that, by compiling the definitions across the world, they can inspire more evaluation into whether such guidelines benefit public health and, if so, what strategies would increase the number of nations that develop and disseminate them.

“Drinking guidelines are not set in stone, and what is summarized in our study should be considered within the context of the data collection period, the summer of 2015.

“In January 2016, the UK Department of Health proposed new drinking guidelines that replace a daily consumption guideline with a weekly recommended limit of 112 g of ethanol for both males and females.

“The newly proposed guidelines, upon which the government is now taking consultation, represents a significant change and other nations, of course, may also alter their guidelines some day in response to different scientific and policy forces.

“We therefore intend to update this report in the future and would be grateful to international colleagues who inform us of developments in their countries regarding standard drink definitions and drinking guidelines.”

Source: Addiction, 2016, DOI:10.1111/add.13341

Title: Governmental standard drink definitions and low-risk alcohol consumption guidelines in 37 countries

Authors: Agnieszka Kalinowski and Keith Humphreys