What’s going on?
Last week, a team involved in the Women’s Health Initiative Observational Study published an analysis showing an association between high consumption of artificially sweetened beverages (aka diet soda) and an increased risk for stroke
What does this mean?
The Women’s Health Initiative (WHI) is a huge study with over 90,000 participants, so there is some strength to this analysis. And while the analysis shows there is an association between diet soda and an increased risk for stroke, you cannot draw the conclusion that diet soda causes strokes.
This is not the first time a study showed this result. In 2017, an analysis of almost 3,000 participants in the Framingham Heart Study showed an association between diet soda and increased stroke risk as well.
Why should I care?
The big picture
These studies are great for looking at how people do over a long period of time, but they are not very good at determining cause and effect. Possible explanations for the association between diet soda and stroke risk include survival bias and reverse causation, as described in this article from Harvard Health about the Framingham analysis.
To really show causation, we would need to follow a large group of people over a long period of time. The group would need to be split in two smaller groups, and theses smaller groups would need to be identical in every way except for whether or not the two groups drink diet soda. And the two groups could not be told whether or not they are drinking diet or regular soda. For human studies, this would be almost impossible to pull off. (If you’re interested in learning more about association and causation, check out this article)
For you personally
Every week new studies are published, but it is hard to tell what is useful or not. Just remember that science is slow, and nothing changes over night.
If you drink diet soda, maybe you should cut back, but not just because of this study. Any kind of soda (diet or otherwise) contains carbonated water, which is slightly acidic and not good for your teeth. And there is one study that shows an association between diet soda and weight gain, but then we go down that rabbit hole of other explanations for that association – like drinking diet soda may make some people feel like they can splurge in other areas…
I’ll let you in on a secret: I’m a diet soda drinker. I know I probably shouldn’t drink as much as I do, and on days when I don’t drink diet soda, I feel a little caffeine withdrawal (which is yet another compound that may or may not be good for you…). And I’ve noticed that some types of artificial sweeteners tend to make me feel a little strange, so I tend to avoid them.
The bottom line is: you know your body best. Do what you think is best for you and don’t worry too much about these studies.