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Harvard Health Blog
Does drinking diet soda raise the risk of a stroke?
- By Julie Corliss, Executive Editor, Harvard Heart Letter
For diet soda fans, recent news reports linking these popular drinks to higher risk of stroke may have been alarming. A closer look at the study behind the headlines suggests there’s no need to panic. But beverages naturally low in calories are probably a healthier option than artificially sweetened drinks.
The study included 2,888 people ages 45 and older from the long-running Framingham Heart Study, all of whom filled out diet questionnaires up to three times over a seven-year period. People who said they drank at least one artificially sweetened soda a day were about twice as likely to have a stroke over the following decade when compared to those who drank less than one a week. Drinking regular, sugar-sweetened sodas or beverages did not appear to raise stroke risk.
However, these types of studies can’t prove cause and effect, only an association. Also, only 97 people (3%) had strokes during the follow-up, which means only two or three of those strokes could possibly be attributed to drinking diet soda, says Dr. Kathryn Rexrode, an associate professor of medicine at Harvard-affiliated Brigham and Women’s Hospital who co-authored an earlier, larger study looking at soda consumption and stroke risk.
Stroke risk from all sodas?
That study detected a slightly higher risk of stroke in people who drank more than one soda per day, regardless of whether it contained sugar or an artificial sweetener. Although the latest study didn’t detect a higher stroke risk from sugary beverages, that certainly doesn’t suggest they are a better choice than diet sodas. Many studies have already shown that drinking sugary beverages on a regular basis can lead to weight gain, diabetes, high blood pressure, heart disease, and stroke, she notes.
In fact, one possible explanation why sugary beverages weren’t linked to stroke in the recent study might be a phenomenon known as survival bias. In this case, that would mean that people who drank a lot of sugar-sweetened beverages may have died earlier from other illnesses such as heart disease.
Conversely, diet beverages may have shown a link to stroke because of a different issue, called reverse causation. In an attempt to be healthier, people who are overweight or have diabetes may be more likely to choose diet drinks over sugary ones. Their heightened stroke risk may result from their health problems rather than their beverage choice. “We might just be measuring the residual impact of obesity and diabetes,” says Dr. Rexrode.
Artificial sweeteners: Other shortcomings
Another conundrum: researchers don’t have any plausible explanation for why artificial sweeteners might increase stroke risk. Still, there may be other reasons to ditch them.
If you use artificial sweeteners to control your weight, you should know that the support for that strategy is pretty shaky. Some evidence suggests that artificial sweeteners make people crave sugary, high-calorie foods, thereby negating the sweetener’s potential to cut your overall calorie intake. And some experts believe that people who use these high-intensity sweeteners (which are hundreds of times sweeter than sugar) may come to find naturally sweet foods, such as fruit, less appealing and less-sweet foods, such as vegetables, downright unpalatable. If so, those people might be missing out on the many heart-protecting nutrients found in fresh, natural foods.
But Dr. Rexrode isn’t a stickler when it comes to diet soda. “I encourage my patients to eliminate regular soda and other sugar-sweetened drinks to avoid empty calories,” she says. “But if someone says they can’t do without a Coke in the morning to wake up, I’ll encourage them to switch to coffee or diet Coke.” Water is an even better choice, however. “There are a lot of ways to make it more appealing, both visually and taste-wise.” she adds. Try flavoring flat or sparkling water with a splash of fruit juice, or add frozen fruit, cucumber, or crushed mint.
About the Author
Julie Corliss, Executive Editor, Harvard Heart Letter
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No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.
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