Getty Images, stock Pizza is not all bad, but fewer than 1 percent of American teens have ideal diets, plus they don't exercise enough, according to new research.

A stunning 80 percent of U.S. teenagers are eating diets that put them on a clear path to heart disease, researchers reported on Monday.

They’re eating too much fat, salt and sugar and not eating enough fruits and vegetables, the American Heart Association study found. Just 1 percent ate what the Heart Association considers a perfectly healthy diet.

Plus they don’t exercise enough, says Christina Shay of the the University of Oklahoma Health Sciences Center, who led the study.

“The far less-than-optimal physical activity levels and dietary intake of current U.S. teenagers, is translating into obesity and overweight that, in turn, is likely influencing worsening rates of high blood pressure, high cholesterol and blood glucose at these young ages,” Shay said in a statement.

It’s no secret that Americans, and especially teens, eat poor diets. What concerns the Heart Association and doctors is that people may not realize how little slack there is for teenagers to get away with this. The seeds of heart disease are sown in childhood, these experts advise.

“Autopsy findings reported more than a century ago identified fatty streaks in the large arteries of children as young as 6 years of age,” Shay’s team wrote in their report, published in the journal Circulation.

More recent studies have found evidence of early heart disease in children.

The researchers surveyed 4,600 teenagers taking part in a large national study. The teens answered detailed questions about their eating and exercise habits and also underwent medical exams. The team looked for their blood pressure, cholesterol and blood sugar levels, as well as weight and diet and exercise.

Fewer than 80 percent scored well on diet. Just 1 percent met the ideal guidelines of 4.5 or more cups a day of fruits and vegetables, two servings of fish a week, 3 ounces a day of whole grains, less than 1,500 mg of salt a day and no more than 450 calories worth of sugar-sweetened drinks a week.

Only 45 percent scored acceptably on five or more of the factors. Only 44 percent of girls and 67 percent of boys reported idea physicial activity levels. Just two-thirds had ideal weights.

A third already had unhealth cholesterol levels or were on the way there, the report found. The good news came on blood pressure – 90 percent of the girls and 78 percent of the boys had healthy blood pressure. And 66 to 70 percent had never tried smoking.

Heart disease is the No. 1 killer in the United States. The Heart Association says 80 percent of cases can be prevented with healthy habits.

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