February 9/Los Angeles/States News Service -- Even drinking diet soda instead of the sugar variety could result in a much higher risk of vascular events compared to those who do not drink soda, according to research presented at the American Stroke Association's International Stroke Conference 2011.

In findings involving 2,564 people in the large, multi-ethnic Northern Manhattan Study (NOMAS), scientists said people who drank diet soda every day had a 61% higher risk of vascular events than those who reported no soda drinking.

"If our results are confirmed with future studies, then it would suggest that diet soda may not be the optimal substitute for sugar-sweetened beverages for protection against vascular outcomes," said Hannah Gardener, Sc.D., lead author and epidemiologist at the University of Miami Miller School of Medicine in Miami, Fla.

NOMAS is a collaboration of investigators at Columbia University in New York and Miamis Miller School of Medicine, launched in 1993 to examine stroke incidence and risk factors in a multi-ethnic urban population. A total of 3,298 participants over 40 years old (average age 69) were enrolled through 2001 and continue to be followed. Some 63% were women; 21% were white, 24% black and 53% Hispanic.

In the soda study, researchers asked subjects at the outset to report how much and what kind of soda they drank. Based on the data, they grouped participants into seven consumption categories: no soda (meaning less than one soda of any kind per month); moderate regular soda only (between one per month and six per week), daily regular soda (at least one per day); moderate diet soda only; daily diet soda only; and two groups of people who drink both types: moderate diet and any regular, and daily diet with any regular.

During an average follow-up of 9.3 years, 559 vascular events occurred (including ischemic and hemorrhagic stroke, which is caused by rupture of a weakened blood vessel). Researchers accounted for participants age, sex, race or ethnicity, smoking status, exercise, alcohol consumption and daily caloric intake. Even after researchers also accounted for patients metabolic syndrome, peripheral vascular disease and heart disease history, the increased risk persisted at a rate 48% higher.

Participants reporting their dietary behavior is a key limitation of the study, Gardener said.

In the soda study, investigators also lacked data on types of diet and regular drinks consumed, preventing analysis of whether variations among brands or changes over time in coloring and sweeteners might have played a role.

Co-authors for the soda study were: Tatjana Rundek, M.D., Ph.D.; Clinton Wright, M.D., M.S.; Julio Vieira, B.A.; Mitchell S. Elkind, M.D., M.S.; and Ralph L. Sacco, M.D., M.S.

Funding for the study was provided by a Javits award from The National Institute of Neurological Disorders and Stroke and the Evelyn F. McKnight Brain Institute.

From the February 21, 2011, Prepared Foods E-dition