The researchers then controlled for the presence of metabolic syndrome, vascular disease in the limbs and heart disease history; the link still held, albeit at 48 percent.
While the study found a possible association between diet soda and stroke risk, it did not demonstrate a cause and effect. And experts note that research presented at meetings has not been subjected to the same type of rigorous scrutiny given to research published in peer-reviewed medical journals.
"If our study is replicated," Gardener said, "it would suggest diet soda is not optimal."
Dr. Patrick Lyden, chief of neurology at Cedars-Sinai Medical Center in Los Angeles, reviewed the findings but was not involved in the research. "My first thought was, 'The correlation has to be accidental,'" he said.
But he said the science in the study looks sound. "There still could be some sort of accidental correlation," he said. What to do? "Wait for repeated studies to show a risk and in the meantime, all things in moderation."
He tells his patients to avoid soda, whether diet or regular, on a daily basis. "An occasional soda never hurt anybody," he said. "Once or twice a week to me seems to be rational."
In a separate study, Gardener also found high salt intake was linked to a higher risk of stroke. Using the same data, she looked at 2,657 participants of NOMAS, evaluating their salt intake and following them for nearly 10 years.
During that time, 187 ischemic strokes occurred. Those who consumed more than 4,000 milligrams a day of sodium had more than double the risk of ischemic stroke than those who consumed less than 1,500 milligrams a day.
How much salt is ideal? The American Heart Association recommends less than 1,500 milligrams a day. The current U.S. Dietary Guidelines for Americans recommends eating less than 2,300 milligrams a day and even less
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