Additionally, people who drink artifical sweeteners were three times as likely to develop both stroke and dementia. The results, however, come with a host of caution flags raised by experts.
The researchers said future studies should look at the effect of diet drinks on factors known to increase the risk of stroke and dementia, such as high blood pressure.
But Gavin Partington, director-general of the British Soft Drinks Association, the industry body said: 'Despite their claims, the authors of this observational study admit they found no cause and effect and provide no science-based evidence whatsoever to support their theories. Its more hypothesis-generating..
Matthew Pase, Ph.D., a study co-author from the Department of Neurology at the Boston University School of Medicine in MA, and his colleagues published their findings today in the journal Stroke.
Now, because this was an observational study-meaning it identifies trends over time-it can't definitely prove that artificial sweeteners somehow cause dementia or stroke. The second, published in Alzheimer's & Dementia, found that higher consumption of sugary beverages was associated with markers for pre-clinical Alzheimer's disease.
Researchers analyzed the self-reported diets of two sets of people participating in the Framingham Heart Study, the longest-running heart study in the USA, funded by the National Heart, Lung, and Blood Institute and run in partnership with Boston University.
The researchers analyzed data on nearly 2,900 people over the age of 45 for the stroke study and almost 1,500 people over age 60 for the dementia study. The researchers reviewed this information at three different points in time over a period of seven years.
The team followed the subjects over the next 10 years to monitor the development of stroke and dementia. Of those, 82 were ischemic. This study, the authors noted, has the same limitations as the Alzheimer's & Disease analysis, as well as another important one: The association could be a case of reverse causality, "whereby sicker individuals consume diet beverages as a means of negating a further deterioration of health". Of those, 63 were diagnosed as Alzheimers disease.
Those consuming at least a can of so-called diet drinks every day were 2.96 times more likely to suffer an ischaemic stroke and 2.89 times more likely to develop Alzheimer's disease than those who drank them less than once a week, they found.
Pase said that the next steps in the research was to look more closely at the positive food and drinks choices people can make to improve health.
The American Beverage Association concurred.
When asked about a variety of health issues, including losing weight, constipation, and diabetes, participants in the survey said that lower-sodium products would prevent all of them.
We have a robust body of literature on the adverse effects of sugary drinks. "The evidence is clear that drinking water is healthy", Gardener said.
However, sugary beverages weren't tied to an increased risk of stroke or dementia - a finding the authors called "intriguing", and one that could have been due to survival bias.
In an accompanying commentary, Ralph Sacco, M.D., a former president of the American Heart Association and the chairman of the department of neurology at the Miller School of Medicine at University of Miami in Florida, says that current research is "inconclusive" in determining whether or not drinking artificially sweetened beverages frequently can lead stroke, dementia, and other heart-related conditions.
Consumers shouldnt overinterpret the latest studys results, said Christopher Gardner, Ph.D., director of Nutrition Studies at the Stanford Prevention Research Center and a professor of medicine at Stanford University.
Diet drinks account for a quarter of the sweetened beverages market but there is growing evidence they are not as healthy as previously thought. Nobody ever said diet sodas were a health food.. "It is also worth noting that our sample consumed diet soda more frequently than sugar-sweetened soda and this may contribute to differences in findings between regular and diet soda".
So, the bottom line is, Have more water and have less diet soda, he said.