Artificially-sweetened diet drinks made up roughly a third of all beverages consumed by adults in the U.S between 2007 and 2010. Beverages containing low- or no-calorie sweeteners were the most frequently consumed artificially-sweetened products worldwide.

One reason for diet drinks' popularity is that people often assume that since they have no or few calories, they are healthy. This appears not to be true, as the findings of a new study of postmenopausal women show. The study found that drinking multiple diet beverages daily can raise the risk of heart disease and a particular type of stroke.

Women who drank artificially-sweetened drinks two or more times per day had a 31 percent increased risk of ischemic stroke.

“Our research and other observational studies have shown that artificially sweetened beverages may not be harmless, and high consumption is associated with a higher risk of stroke and heart disease,” Yasmin Mossavar-Rahmani, lead author of the study, told TheDoctor.

A 30 Percent Higher Risk of Stroke

The researchers analyzed data from nearly 82,000 postmenopausal women between the ages of 50 and 79 years old who were enrolled in the Women's Health Initiative study. They followed women in the racially diverse group on average for about 12 years. At their three-year evaluation, the women were asked how often during the last three months they had consumed artificially sweetened beverages. The researchers accounted for stroke risk factors such as age, high blood pressure and smoking.

Compared to women who drank diet beverages less than once a week or not at all, women who drank artificially-sweetened drinks two or more times per day had a 23 percent increased risk of stroke; 31 percent increased risk of ischemic stroke, or a stroke caused by a blood clot; 24 percent increased risk of heart disease; and a 16 percent higher risk of death from any cause.

All women, even those without a history of diabetes or heart disease, who drank two or more diet beverages daily had nearly two and a half times the risk of ischemic stroke compared to women who drank them rarely or not at all. Obese women with no history of heart disease or diabetes had two times the risk of ischemic stroke; and African American women without a history of heart disease and diabetes had nearly four times the risk of ischemic stroke if they drank two or more diet drinks a day.

Try Water

Women should talk to their health professional about their consumption of diet drinks, said Mossavar-Rahmani, an associate clinical professor of epidemiology and population health at the Albert Einstein College of Medicine in New York, “Women must think about what they need to do and how they can incorporate small changes into their diet.” Giving up a two-or-more a day diet drink habit may not be easy, but you if you take baby steps, it's doable.

African American women without a history of heart disease and diabetes had nearly four times the risk of ischemic stroke if they drank two or more diet drinks a day.

Looking for a no-cal beverage? The American Heart Association (AHA) recommends water.

Diet drinks with artificial sweeteners may help dieters transition away from sugar-sweetened beverages and eventually adjust to water as their primary drink. But they should never become a daily part of your diet. As Rachel Johnson, professor emeritus of nutrition at the University of Vermont and chair of the writing group for the AHA Low-Calorie Sweetened Beverages and Cardiometabolic Health science advisory, warns, “Since long-term clinical trial data about the effects of artificially sweetened diet drinks on cardiovascular health are unavailable, it may be smart to limit their prolonged use.”

The study and a related editorial were published in Stroke.