CHICAGO - Could too much sugar be deadly? The biggest study of its kind suggests the answer is yes, at least when it comes to fatal heart problems.

It doesn't take all that much extra sugar, hidden in many processed foods, to substantially raise the risk, the researchers found, and most Americans eat more than the safest amount.

Having a cinnamon roll with your morning coffee, a super-sized sugary soda at lunch and a scoop of ice cream after dinner would put you in the highest risk category in the study. That means your chance of dying prematurely from heart problems is nearly three times greater than for people who eat only foods with little added sugar.

For someone who normally eats 2,000 calories daily, even consuming two 12-ounce cans of soda substantially increases the risk. For most American adults, sodas and other sugary drinks are the main source of added sugar.

Lead author Quanhe Yang of the U.S. Centers of Disease Control and Prevention called the results sobering and said it's the first nationally representative study to examine the issue.

Scientists aren't certain exactly how sugar may contribute to deadly heart problems, but it has been shown to increase blood pressure and levels of unhealthy cholesterol and triglycerides; and also may increase signs of inflammation linked with heart disease, said Rachel Johnson, head of the American Heart Association's nutrition committee and a University of Vermont nutrition professor.

Yang and colleagues analyzed national health surveys between 1988 and 2010 that included questions about people's diets. The authors used national death data to calculate risks of dying during 15 years of follow-up.

Overall, more than 30,000 American adults aged 44 on average were involved.

Previous studies have linked diets high in sugar with increased risks for non-fatal heart problems, and with obesity, which can also lead to heart trouble. But in the new study, obesity didn't explain the link between sugary diets and death. That link was found even in normal-weight people who ate lots of added sugar.

"Too much sugar does not just make us fat; it can also make us sick," said Laura Schmidt, a health policy specialist at the University of California, San Francisco. She wrote an editorial accompanying the study in Monday's JAMA Internal Medicine.

The researchers focused on sugar added to foods or drinks, or sprinkled in coffee or cereal. Even foods that don't taste sweet have added sugar, including many brands of bread, tomato sauce and salad dressing. Naturally occurring sugar wasn't counted.