Women who drink the most diet sodas may also be more likely to develop heart disease and even to die, according to a new study published Saturday.
Researchers found women who drank two or more diet drinks a day were 30 percent more likely to have a heart attack or other cardiovascular "event," and 50 percent more likely to die, than women who rarely touch such drinks.
The findings, being presented at a meeting of the American College of Cardiology, don't suggest that the drinks themselves are killers. But women who toss back too many diet sodas may be trying to make up for unhealthy habits, experts say.
"Our study suggests an association between higher diet drink consumption and mortality," said Dr. Ankur Vyas, a cardiovascular disease expert at the University of Iowa Hospitals and Clinic, who led the study.
"It's not an extreme risk," he added.
Research has long shown that artificially sweetened drinks are not health drinks. While they may help people avoid more dangerous sugary sodas, studies show they don't help people lose weight.
Vyas's team studied nearly 60,000 middle-aged women taking part in a decade-long study of women's health. They filled out a questionnaire on food and drinks as part of the study, including detailed questions on diet sodas and diet fruit drinks.
After just under nine years, the researchers checked to see what happened to the womens' health. They found that 8.5 percent of the women who drank two or more diet drinks a day had some sort of heart disease, compared to 6.8 percent of those who drank four or fewer drinks a week and 7.2 percent in those who drank none or just a couple a month.
"We only found an association, so we can't say that diet drinks cause these problems," Vyas said.
And that's a fairly low risk, given that heart disease is the No. 1 killer in the United States and is very, very common.
The women who drank the most drinks were also more likely to smoke, to be overweight, to have diabetes and to have high blood pressure, Vyas noted.
The American Beverage Association, an industry group that lobbies on behalf of soft drink manufacturers, echoed that point in a statement prepared in response to the study. Because of those other risk factors, "it is impossible to attribute their cardiovascular health issues to their diet beverage intake," the group said.
The researchers say it is not clear what is causing the effects in women — whether it is something in diet drinks, or whether women who drink many diet drinks have more unhealthy habits or risk factors than women who do not.
About one in five people in the U.S. consume diet drinks on a given day, according to federal survey data.