MONDAY, Jan. 10 (HealthDay News) -- Teens whose diets include lots of sugary drinks and foods show physical signs that they are at increased risk for heart disease as adults, researchers from Emory University report.

Among 2,157 teens who took part in the National Health and Nutrition Examination Survey, the average amount of added sugar eaten in a day was 119 grams (476 calories), which was 21.4 percent of all the calories these teens consumed daily, the researchers noted.

"We need to be aware of sugar consumption," said lead researcher and postdoctoral fellow Jean Welsh.

"It's a significant contributor of calories to our diet and there are these associations that may prove to be very negative," she said. "Sugar-sweetened soft drinks and sodas are the major contributor of added sugar and are a major source of calories without other important nutrients."

Awareness of the negative effects of added sugar may help people, particularly teens, cut down on the amount of sugar they consume, Welsh added.

"Parents and adolescents need to become aware of the amount of added sugar they are consuming and be aware that there may be some negative health implications if not now, then down the line," she said.

The report is published in the Jan. 10 online edition of Circulation.

Welsh's team found that teens who consumed the most added sugar had 9 percent higher LDL ("bad") cholesterol levels, and 10 percent higher triglyceride levels (another type of blood fat), compared with those who consumed the least added sugar. Teens who took in the highest amount of added sugar also had lower levels of HDL ("good") cholesterol than those who consumed the least amount of added sugar.

In addition, teens who consumed the highest amount of added sugar showed signs of insulin resistance, which can lead to diabetes and its associated risk of heart disease, the researchers found.

The American Heart Association has recommended an upper limit for added sugars intake, based on the number of calories you need. "Most American women [teens included] should consume no more than 100 calories of added sugars per day; most men, no more than 150 calories," the association states.

One caveat to these findings is that because of the way the study was done it is not clear if added sugars caused the differing cholesterol levels, only that they are linked. In addition, the data are only for one day and may not reflect the teen's usual diet, the researchers noted.

Commenting on the study, Dr. David L. Katz, director of the Prevention Research Center at Yale University School of Medicine, said that "this study does not prove that dietary sugar is a cardiac risk factor in this population, but it strongly suggests it."

The paper has three important messages, he said. First, dietary sugar intake in a representative population of teenagers is nearly double the recommended level.

Second, the higher the intake of sugar, the greater the signs of cardiac risk, including elevated LDL ("bad") cholesterol and low HDL ("good") cholesterol. Third, the apparent harms of excess sugar are greater in overweight than in lean adolescents.

"Sugar is by no means the sole dietary threat to the health of adolescents, or adults," Katz said. "But we now have evidence it certainly counts among the important threats to both. Reducing sugar intake by adolescents, to prevent them becoming adults with diabetes or heart disease, is a legitimate priority in public health nutrition," he said.

More information

For more information on dietary sugar, visit the American Heart Association.