Researchers observe an increased risk of vascular disease, including heart attack and stroke, among those who drink diet soda every day.
LOS ANGELES—Consumption of diet soda is associated with a greater risk of vascular events than regular soft drink consumption, according to findings from a study presented at the 2011 International Stroke Conference.
Hannah Gardener, ScD, Assistant Scientist, Department of Neurology, University of Miami Miller School of Medicine, and colleagues conducted an observational study about diet and regular soda–drinking behavior and a connection with the risk of vascular events such as stroke, myocardial infarction, and vascular death.
A multi-ethnic cohort of 2,564 participants who had never had a previous stroke or myocardial infarction was selected from the Northern Manhattan Study (NOMAS). Thirty-six percent were men, and the mean age of participants was 69. Annual follow-up was conducted for an average of 9.3 years to determine incidence of stroke, myocardial infarction, or death.
Participants completed questionnaires about their soft drink consumption, and the investigators divided the responses into seven categories—no soda consumption, daily regular only, light regular only, daily diet only, light diet only, light diet/any regular, and daily diet/any regular. The reference group (those who drank neither regular nor diet soda) was the largest, comprising 35% of the total population, and members of the smallest group were those who drank daily diet/any regular.
During the follow-up, 559 new vascular events were recorded—212 strokes (178 ischemic strokes), 149 myocardial infarctions, and 338 vascular deaths.
Results Adjusted for Vascular Risk Factors
After analyzing the NOMAS data and adjusting for demographics and behavioral risk factors (smoking, physical activity, alcohol consumption, calories consumed per day), the investigators observed a 61% increased risk for vascular events among the group who consumed diet soda daily.
After additionally adjusting for vascular risk factors (metabolic syndrome, previous cardiac disease), the researchers found that the association was “attenuated slightly but remained statistically significant” with a 48% increase in risk.
“We also saw a suggested increase among those who consumed diet soda daily in addition to regular soda, but that did not reach statistical significance,” Dr. Gardener reported.
More Research Is Needed
Consumption of diet soda was infrequent in the study population, but Dr. Gardener concluded, “If our results are confirmed with future studies, then it would suggest that diet soda may not be the optimal substitute for sugar-sweetened beverage for protection against vascular outcomes.”
Dr. Gardener also identified several limitations of the observational study, including the potential misclassification of self-reported soft drink consumption, the lack of information on the types of diet and regular soft drinks consumed, the lack of data about diet prior to study period, and data about participants’ diet collected at only one time point.
Dr. Gardener also stressed the study’s importance for future investigation. “Based on our study, it’s too preliminary to suggest any dietary advice.… The next steps are for other longitudinal cohort studies, preferably those that are conducted on a younger population with more diet soda consumption and those with a collection of diet [data] at multiple time points to investigate this question and hopefully confirm our results.… The take-home message is that more studies are needed.
—Ariel Jones