It's no secret that the empty calories in soda and other sugary drinks can contribute to weight gain and obesity. But a new study suggests these beverages also may harm your heart, even if they don't cause you to gain weight.

The study, which followed nearly 43,000 men for an average of 22 years, found that those who habitually drank one 12-ounce sweetened beverage per day were 20% more likely to have a heart attack, fatal or otherwise, than men who drank none.

The association could not be explained by obesity or weight gain alone. The researchers took into account the men's body mass index, along with their dietary habits, exercise levels, family history of heart disease, and other extentuating factors.

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Sugary-beverage consumption "appears to be an independent risk factor for heart disease," says lead author Frank Hu, M.D., a professor of nutrition and epidemiology at the Harvard School of Public Health, in Boston.

Artificially sweetened diet drinks were not linked to heart attacks, as they have been in some other recent studies. And only daily or near-daily consumption of sugary drinks measurably increased heart-attack risk.

The study was published this week in the American Heart Association journal Circulation.

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Several factors besides body weight—or, more likely, a combination of factors—could explain the findings, Hu says. For instance, he says, sugary beverages have been linked to high triglycerides and low "good" cholesterol (HDL), which could increase heart-attack risk without being accompanied by obesity.

Sugary beverages also are believed to promote inflammation, an immune-system response involved in both heart disease and insulin resistance, a major risk factor for type 2 diabetes. Finally, Hu says, sugary drinks have been associated with the accumulation of belly fat, which can increase a man's risk of heart attacks even if he isn't obese.

Blood samples taken from roughly 40% of the men during the study supported some of these hypotheses. Men who consumed sugary beverages at least once a day had higher triglyceride levels, lower HDL levels, and higher levels of a marker of inflammation known as C-reactive protein (CRP). They also had higher levels of leptin, a hormone that helps regulate metabolism.

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The study had some important limitations. Most notably, the researchers measured beverage consumption every four years using food questionnaires. Although this is a commonly used research method, it relies on the study participants' memory and is therefore less than exact.

In addition, the new research was part of an ongoing study, funded by the National Institutes of Health, that includes only male health professionals, almost all of whom are white. That may limit the relevance of the findings to other groups.

However, the findings do closely resemble those of a similar study in women, known as the Nurses Health Study.

"We already know that sugary beverages are associated with increased obesity, type 2 diabetes, and other metabolic issues," Hu says. "This adds further evidence that sugary beverages are detrimental to our health."

Copyright Health Magazine 2011