The trouble with drinking guidelines: What, in the world, is a standard drink?

Researchers looked at 75 countries that might be expected to provide low-risk drinking guidelines and a definition of a 'standard drink'. Only 37 countries (under 50%) did so, and their guidelines and 'standard drink' definitions were surprisingly inconsistent.

The size of a standard drink varies by 250%, from a low of 8 g in Iceland and the United Kingdom to a high of 20 g in Austria. An 8 g 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.

In the most conservative countries, low-risk consumption means drinking no more than 10 g of pure ethanol per day for women, 20 g for men.

Want to drink more? In Chile, you can drink 56 g per day and still be a low-risk drinker.

Got a reason to celebrate? In Australia, Canada, Denmark, Fiji, France, Mexico, New Zealand, Poland, and the UK, you are allowed to drink more on special occasions.

Tired of the old double standard? In Australia, Grenada, Portugal, and South Africa, low-risk drinking guidelines are the same for women and men. The UK joins that list with its new guidelines.

Co-author of the report Keith Humphreys says, "If you think your country should have a different definition of a standard drink or low-risk drinking, take heart -- there's probably another country that agrees with you."

The World Health Organization defines a standard drink as 10 g of pure ethanol, with both men and women advised not to exceed 2 standard drinks per day. Although the WHO's definition of a standard drink is the one most often used, 50% of countries with drinking guidelines don't use it.