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Are diet soft drinks really a healthier option than sugar-sweetened beverages?

Many people undoubtedly consume the diet variety to cut back on calories, hoping to prevent weight gain. After all, being overweight can contribute to a multitude of illnesses.

But a new study, presented this week at an international stroke conference in Los Angeles, found a link between diet drinks and cardiovascular disease. The same association was not seen in people who consumed regular soda.

The findings are based on 2,564 New York adults with an average age of 69. At the outset of the study, the volunteers were asked to complete a questionnaire about their eating habits, including their pop consumption.

The researchers then monitored the health of the participants for about nine years.

The results revealed that people who drank at least one diet pop a day had a 48 per cent higher risk of having a heart attack, stroke or fatal cardiac event than those who reported no soda consumption.

By contrast, those who downed regular soda daily faced no greater or lesser risk than those who shunned all forms of pop.

"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," said the lead author of the study, Hannah Gardener of the University of Miami Miller School of Medicine.

What might account for these remarkable findings? Dr. Gardener, an epidemiologist, shies away from questions of biology and sticks to her numbers. "As far as I know, we don't have any clear evidence for a mechanism. To say anything at this point would be speculation."

Even so, this isn't the first study to raise questions about diet drinks. Earlier research has suggested that diet-soda drinkers faced an elevated risk of metabolic syndrome, a worrisome collection of risk factors for cardiovascular disease. And some animal studies have indicated artificial sweeteners may disrupt the normal digestive process - and cause the body to absorb more sugars from the gut.

One major weakness of the study is that it lacks information on the specific drinks people consumed. The ingredients of different products can vary greatly. What's more, it's possible that people who gravitate to diet soda share other lifestyle quirks that put them at risk of heart troubles.

Until more research is done, Dr. Gardener said, it's too soon to urge people to shun diet soda. "In the meantime, if consumers want to be conservative, it's important to keep in mind that there is no nutritional value in diet or regular sodas. And certainly the health consequences of regular soda - sugar-sweetened beverages - have been well documented. So cutting either out of your diet in not going to leave you with nutritional or vitamin holes," she added. Perhaps variety is the answer; people do have lots of choice when it comes to beverages. Of course, nothing beats just plain water.