According to a study of more than 2,500 people presented today as a poster at the American Stroke Association International Stroke Conference in Los Angeles, people who drank diet soda daily had a 61 percent increased risk of cardiovascular events compared to those who drank no soda, even when accounting for smoking, physical activity, alcohol consumption and calories consumed per day.

But the questionnaire-based study garnered criticism by experts in diet, nutrition and vascular disease."This study suggests that diet soda is not an optimal substitute for sugar-sweetened beverages, and may be associated with a greater risk of stroke,"Hannah Gardener of the University of Miami and her colleagues reported at the conference.

"This study has major flaws and should not change anyone's diet soda consumption," said ABC News Chief Health and Medical Editor Dr. Richard Besser.

The researchers used data obtained though the multi-ethnic, population-based Northern Manhattan Study to examine risk factors for stroke, heart attack and other vascular events such as blood clots in the limbs. While 901 participants reported drinking no soda at the start of the study, 163 said they drank one or more diet sodas per day.

"One of the many flaws here is that participants were asked about soda intake at only one point in time, when they entered the study," Besser said. "It is difficult to imagine that people's intake of soda is constant during that period."