People who drink diet soda every day may be at higher risk for having a stroke or developing dementia, according to a new study published online on April 21 in Stroke, a journal of the American Heart Association.
Sugary foods, including fruit juices, fruit drinks, and sodas, have long been associated with an increased risk of heart disease, obesity, and diabetes. However, studies analyzing the link between stroke and sugary drinks or drinks made with artificial sugar have yielded conflicting results.
That's why researchers at Boston University and Tufts University decided to assess the link between long-term, daily consumption of regular soda and diet soda and rates of stroke or dementia over 10 years.
Researchers analyzed data on almost 3,000 people in the long-running Framingham Heart Study Offspring cohort, which studies associations between lifestyle and heart health in people living in Framingham, MA. The researchers reviewed answers on a food-frequency questionnaire that participants completed three times over a 10-year period from 1991 to 2001 to identify those who consumed regular soda, diet soda, and other sugar-sweetened beverages, including fruit juice and fruit drinks, on a daily basis.
To assess the rate of stroke, researchers reviewed the health data of 2,888 people, age 45 and older, and found that those who drank diet soda daily had an almost 3-times increased risk of ischemic stroke, a stroke caused by a blood clot in the brain.
To assess the rate of dementia, researchers looked at the health data of 1,484 people, age 60 and older, and found that daily diet soda drinkers likewise had an almost 3-times increased risk of developing dementia.
The researchers found no association between daily consumption of sugary soda and either stroke or dementia.
Researchers don't know the exact reasons why diet soda appears to increase stroke and dementia risk, nor did they examine different risks linked with different types of artificial sweeteners. What they do know, they say, is that diet soda is bad for the brain.
Although regular soda and other sugary drinks weren't implicated, enough research exists to show that they aren't good for health, either.
"Maybe good old-fashioned water is something we need to get used to," said Sudha Seshadri, MD, professor of neurology at Boston University School of Medicine and a senior study author, in a press release accompanying the study.