Diet Sodas - Are the Dangers in the Chemicals or the Headlines?

BY HARRIET HALL, M.D.

In April 2017, there was a flurry of news reports with alarming headlines:

• “Diet Sodas May Raise Risk of Dementia and Stroke, Study Finds”
• “A Daily Diet Soda Habit May Be Linked to Dementia–Alzheimer’s”
• “Is Diet Soda Harming Your Brain Health?”
• “Diet Sodas Tied to Dementia and Stroke”
• “Here’s Another Reason You Might Want to Quit Diet Soda”
• “Drinking Too Much Soda May Be Linked to Alzheimer’s”
• “Is Soda Bad For Your Brain? (And is Diet Soda Worse?)”
• “Diet Soft Drinks Triple the Risk of Dementia”
• “Two Things Diet Soda Does to Your Brain”

Some of these headlines were from respectable sources like The New York Times and The Washington Post. It’s not surprising that many people were alarmed by the news and assumed that diet sodas had been proven to cause dementia. Some people were frightened enough to stop drinking diet sodas.

Headlines are designed to get people’s attention so they will read the article. They are notoriously unreliable. The first thing is to check whether the information in the body of the articles matches the headlines; sometimes it doesn’t. Even when the information matches, the article may selectively report some but not all of the studies’ findings, and it may put an unwarranted spin on the meaning of the findings. These headlines all referred to a single study; I wanted to know what that study actually reported, so I read it.

What Did the Study Show?

The study, by Matthew Pase and his colleagues, was published in a reputable journal, Stroke. The subjects were 2,888 individuals in the community-based Framingham Heart Study Offspring cohort. During a 10-year period of observation, 97 subjects over the age of 45 had a stroke: 82 ischemic (restriction of blood flow) as opposed to hemorrhagic (ruptured vessel and bleeding), and 81 subjects over the age of 60 developed dementia (63 consistent with Alzheimer’s). They estimated cumulative consumption of artificially-sweetened soft drinks based on self-reports on a food-frequency questionnaire. They found that drinking one or more artificially-sweetened soft drinks a day was associated with a nearly 3-fold increase in the incidence of ischemic stroke, all-cause dementia, and Alzheimer’s disease compared to drinking none. Sugar-sweetened soft drinks were not associated with stroke or dementia. […]

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