Just as you were starting to feel virtuous for having switched from sugary sodas to low- or no-calorie substitutes, a new study comes along suggesting that diet sodas might be bad for your head and your heart.

The study, which followed more than 2,500 New Yorkers for nine or more years, found that people who drank diet soda every day had a 61 percent higher risk of vascular events, including stroke and heart attack, than those who completely eschewed the diet drinks, according to researchers who presented their results today at the American Stroke Association’s International Stroke Conference in Los Angeles.

Still, the researchers aren’t ready to tell consumers to skip diet sodas. More studies need to be done before that happens, said the report’s lead author Hannah Gardener, an epidemiologist at the University of Miami Miller School of Medicine.

“I think diet soda drinkers need to stay tuned,” Gardener said. “I don’t think that anyone should be changing their behaviors based on one study. Hopefully this will motivate other researchers to do more studies.”

That advice may not stop some from skipping their diet drinks. “This is pretty scary,” said Denise Gainey, a 49-year-old administrative assistant from Amelia, Va. Worried that she might have inherited a higher risk of heart disease, Gainey wants to be careful. “I guess I’ll just be drinking a lot more water,” she said.

For the new study, researchers surveyed 2,564 north Manhattan residents about their eating behaviors, exercise habits, as well as cigarette and alcohol consumption. The study volunteers were also given physical check-ups that included blood pressure measurements and blood tests for cholesterol and other factors that might affect the risk for heart attack and stroke.

The increased likelihood of vascular events remained even after Gardener and her colleagues accounted for risk factors, such as smoking, high blood pressure and High cholesterol levels. Pointing the finger more squarely at diet drinks, the researchers found no increased risk among people who drank regular soda.

Does this mean there’s something in diet sodas that hurts our blood vessels? Nobody knows the answer to that question, yet, Gardener said. There could be something else that people who drink diet sodas have in common, she explained.

For example, it’s possible that people who drink diet sodas are replacing those saved sugar calories with other unhealthy choices, Gardener said.

That explanation makes a lot of sense to Dr. Nehal N. Mehta, director of inflammatory risk cardiology at the University of Pennsylvania. Although the researchers know the total calories study volunteers were consuming, they weren’t able to account for unhealthy eating habits, Mehta said.

“Maybe along with the diet soda, people are grabbing a Big Mac and a large fries,” Mehta said. “Soda may not be the villain. It may be the other things people consume in association with diet soda. After all, what goes better with pizza or fries than a soda?”

That said, it is always possible that there is something about diet soda that leads to vascular problems, Mehta said, adding that this is the second study to associate diet soda with health issues. An earlier study found that diet soda consumption was linked to an increased risk of metabolic syndrome, which is also a risk factor for heart problems and stroke.

Caramel coloring linked to vascular issues
Further, Mehta said, there are animal studies suggesting a link between vascular problems and caramel-containing products. Among other things, caramel is the ingredient that gives the dark color to sodas like Coke and Pepsi, he explained.

Despite all of that, you probably don’t want to give up diet soda until — and if — larger studies confirm the results of this one, Mehta said.

That is, unless you’re someone with a lot of risk factors for stroke or heart disease, said Dr. Tudor Jovin, an associate professor of neurology and medicine and director of the Stroke Institute at the University of Pittsburgh Medical Center.

“People with a lot of risk factors for vascular disease, might want to reduce the amount of diet soda they consume,” Jovin said. “Those risk factors would include high blood pressure, diabetes, High cholesterol, smoking, a family history of cardiovascular disease, metabolic syndrome and a history of cardiovascular events.”

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By Linda Carroll
msnbc.com contributor