People who mix alcohol and diet drinks end up with more alcohol on their breath, according to a new study.
People who drank vodka mixed with diet soda had higher alcohol concentrations on their breath than those who drank the same amount of vodka mixed with regular soda, researchers write in Drug and Alcohol Dependence.
Prevention materials should include this information so people know that by trying to avoid some extra calories in a mixed drink, they risk having higher breath alcohol concentrations, write the researchers, led by Amy Stamates of Northern Kentucky University in Highland Heights.
Previous research found similar results, but the findings were not generalizable to real-world scenarios, the researchers add.
For the new study, they had 10 men and 10 women between ages 21 and 30 drink five different mixed beverage combinations over five sessions. The drinks contained varying amounts of vodka and either diet or regular sweetened soda. One drink was just regular soda alone.
The researchers then measured the alcohol concentrations in the participants' breaths for three hours.
They found higher concentrations of alcohol on the breaths of the participants when they drank the mixed beverages containing diet soda.
For a low amount of alcohol, the researchers found breath alcohol concentrations were about 22 percent higher when participants had their beverages mixed with diet soda rather than regular soda.
For a larger amount of alcohol, breath alcohol concentrations were about 25 percent higher when the drinks were made with diet soda.
While there were no differences in the results by gender, the researchers say the findings may be particularly relevant to young women, who are most likely to use diet beverages in their mixed drinks.
Dr. Chris Rayner, a gastroenterologist at the University of Adelaide in Australia, told Reuters Health that so-called gastric emptying is likely the reason for higher alcohol concentrations in the participants' breaths.
In a previous study, Rayner found alcohol left the stomach and entered the bloodstream faster when people used diet drinks in their mixed beverages, compared to when they used regularly sweetened drinks.
"Although it makes good press, I wouldn't interpret the findings as indicating that diet beverages are 'bad,'" said Rayner, who was not involved with the new study.
Instead, he said, the effects of alcohol are mitigated if consumed with nutrients like sugar, because it slows the entry of alcohol into the small intestine, where it is absorbed by the body.
"So my message would be that consuming alcohol without any accompanying nutrients will result in a somewhat higher peak blood alcohol concentration," he said. "However, it is at least as important to consume alcohol in moderation, regardless of whether it is taken with or without food."
The authors of the study were unable to respond to a request for comment by deadline.