June 17, 2008 -- So much for complaining about watered down drinks at your neighboring watering hole. A new study shows your favorite happy hour libation may be stronger -- and larger -- than you think.
It's tough to know the alcoholic content of beverages served in restaurants and bars in the U.S. because establishments rarely post such information, according to background information in the journal Alcoholism: Clinical & Experimental Research. There are no laws in the U.S. requiring establishments to disclose alcoholic beverage serving sizes.
It's often assumed that alcoholic beverages have the same amount of pure alcohol -- 0.6 ounces -- but in reality, the content depends on a number of factors, from glass size and pouring mistakes to percent alcohol by volume (%ABV) of the beer, wine, or spirit. For example, you may have a 15% wine or an 11% wine.
William C. Kerr, senior scientist with the Alcohol Research Group at the Public Health Institute, and colleagues visited 80 bars and restaurants in northern California to see how much alcoholic content might vary in the drinks they ordered. They purchased 480 beer, wine, and spirit drinks and measured the alcohol concentration by volume. The team analyzed the drink samples or used the brand name information to determine its alcohol content.
They compared their alcoholic content to a standard alcoholic drink. In the U.S., a standard drink is generally considered to have 0.6 oz of alcohol.
Kerr's team discovered wide variations in alcohol content. Except for shots and bottled beers, drinks ordered at a bar and restaurant generally contained more than 0.6 oz of alcohol. They also learned that the ordered drinks tended to be larger than standard ones.
The researchers say some of the variation may be due to the establishments' tendencies to stock wines with a higher %ABV, averaging 14% alcoholic content instead of the standard 12%. Overpouring was also a contributing factor.
The findings drive home an important message: No two drinks are the same. Not knowing how much alcohol is really in your drink could have devastating consequences, particularly for those who are planning to drive or operate machinery, or those who are sensitive to alcohol's effects.
"Consumers should be aware of these important differences," the study authors write in the journal article. "It is very difficult for individuals to judge the number of ounces in a wine glass or the %ABV of their wine, beer, or spirits drinks. If both volume and %ABV are each about 25 percent higher than expected, for example, and the consumer has three or four of these drinks, then their intake will be much higher than planned -- about two additional standard drinks for four of these drinks -- and this could have significant and possibly damaging consequences," they say in a news release.
The findings will be published in the September issue of Alcoholism: Clinical & Experimental Research. The results are available online ahead of print at OnlineEarly.