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A new study has found an association between frequent drinking of diet sodas and an increased risk of both stroke and dementia.
Here & Now's Meghna Chakrabarti speaks with Dr. Matthew Pase, the study's lead author, about what it means for the average soda drinker. Pase is a visiting postdoctoral fellow at Boston University School of Medicine, and an investigator at the Framingham Heart Study.
On the study’s findings
"It's important to note that our results are observational, which means we observe trends amongst a large group of people, but our results certainly do not suggest causality. In other words, we can't be sure that diet sodas are causing stroke or causing dementia. But we are seeing associations between those who more frequently consume diet soda, and a higher risk of both stroke and dementia within the next 10 years.”
"Those who were drinking diet soda on a daily basis, their risk for stroke and dementia was about three times as high. As compared to someone who was not drinking diet soda."
On whether the study looked at other possible variables behind the elevated risk
"Now that we're showing this association, it's going to be important to understand why that association might be there to try and understand it in more detail. It's possible that diet sodas are associated with risk factors like obesity and diabetes. This might be linked to a higher risk of stroke, or a higher risk of dementia. But on the other hand, it's also possible that those people who are unhealthy to begin with — say, those who already have diabetes, who already have obesity — gravitate more towards the diet sodas to begin with. So now this is something we really need to understand in more detail, to understand which way the association is going."
On the utility of the study if we can't understand cause and effect
"We don't have a lot of data on how diet beverages relate to a lot of different health outcomes. It takes a long time to develop stroke and a long time to develop dementia. It's not something that's really been investigated before. So now we really need these sorts of studies to investigate, what are the associations between diet beverages and different health outcomes, so that consumers can make informed choices about the beverages that they're having."
On how full-sugar soda is no better than diet soda
"That's an excellent point. We certainly don't recommend that people drink normal or regular sugary sodas. These are known to be associated with a range of different health issues such as weight gain and diabetes. Certainly drinking regular soda is not a healthy option. I guess our study is calling for people to be somewhat cautious about diet beverages, questioning whether they're a healthy alternative. But as I'm saying, we now need more research to investigate this further before we can make solid recommendations."
On how samples of different demographics may affect results
"I agree completely, and that's something we noted in our paper. One interesting thing about our study was that people were much more likely to drink diet beverages as compared to regular sodas. It's possible that we might see different associations in different groups that more frequently consumed regular soda, for example. So now we really are calling for other studies to see if our results hold up in other samples of different participants."
On why the study focuses on stroke and dementia
"These are the two diseases I am most interested in, and thus it's the two diseases I wanted to study. It's important to note that we know that increased sugar is associated with vascular risk factors, and this includes things like obesity and diabetes and high blood pressure. We know in turn that these conditions have adverse effects on the brain. So we felt it was important to understand the associations, therefore, between intake of regular soda, of diet soda, with different aspects of brain health."
This segment aired on April 21, 2017.