Diet Drinks Linked to Increased Stroke and Dementia Risk (in lingua originale)
New question marks over the safety of diet soda have arisen following a study linking intake of artificially sweetened beverages to both stroke and dementia.
The study, published online in Stroke on April 20, showed that consumption of one can of diet soda or more each day was associated with a three times increased risk for stroke and dementia over a 10-year follow-up period compared with individuals who drank no artificially sweetened beverages.
“There are many studies now suggesting detrimental effects of sugary beverages, but I think we also need to consider the possibility that diet drinks may not be healthy alternatives,” lead author, Matthew P. Pase, PhD, Boston University School of Medicine, Massachusetts, told Medscape Medical News.
“We can’t show cause and effect in this study as it is observational in design, but given the popularity of diet drinks we desperately need more research on this question.”
He is not yet recommending against diet beverages based on this study, he added, “but I would urge caution — especially to those individuals who consume multiple diet drinks daily. I believe we need to rethink the place of these drinks.”
It is possible that the observation could be due to reverse causality, he noted. “It is not clear whether the diet sodas are causing stroke and dementia or whether unhealthy people gravitate more towards these drinks than healthier people.
“If you already have cardiovascular risk factors, you are likely to have been advised to lower your sugar intake and so may move away from sugary beverages to diet drinks,” Dr Pase said. “We did find that a higher intake of diet soda was linked to diabetes at baseline, but again we don’t know which came first. Did the diet drinks increase the risk of developing diabetes, or did diabetic patients choose diet drinks as they have to limit their sugar intake?”
The link between diet drinks and dementia became nonsignificant when adjusted for vascular risk factors. Dr Pase suggested this could be because the association may be mediated through vascular risk factors — artificial sweeteners could be increasing vascular risk factors. “Or it could just be that people with vascular risk factors drink more diet sodas, which is perfectly possible as they could have been advised to cut down on sugar.”
The link with ischemic stroke was still there in all models after adjustment for all other risk factors.
Sugar-sweetened beverages were not associated with stroke or dementia risk, but the authors say this should not be taken as evidence that sugary drinks are safe.
“There are many other studies suggesting harmful effects of sugar-sweetened drinks, and we did not have large enough numbers of people consuming sugary drinks in our current study for reliable information on this,” Dr Pase said. “We had much larger numbers of individuals reporting intake of artificially sweetened drinks.”
Another study by the same group, published online in Alzheimer’s and Dementia on March 5, shows a link between consumption of both sugar-sweetened and artificially sweetened beverages and reduction in brain volume in a middle-aged cohort. In the cross-sectional study, the sugary drinks, which included both soda and fruit juice, were also associated with worse episodic memory.
“Greater intake of total sugary beverages, fruit juice, and soft drinks were all associated with characteristics of preclinical Alzheimer’s disease,” the authors concluded. “Additional studies are warranted to confirm our findings and evaluate if sugary beverages are associated longitudinally with worsening of subclinical Alzheimer’s disease and with incident Alzheimer’s disease.”