If you think the teenagers in your life have been eating a lot of unhealthy food – you're probably right.

U.S. adolescents get about two-thirds of their calories from ultra-processed food, and the more they eat, the worse they score on important measures of heart health, a new study says.

Nutritionists started using the term "ultra-processed food" about a decade ago. The study used a diet classification system called NOVA that sums it up as "snacks, drinks, ready meals and many other products created mostly or entirely from substances extracted from foods or derived from food constituents with little if any intact food."

Experts say not all processed foods are unhealthy. Some can still have nutritional value.

The ultra-processed food category includes chips, cookies, candy, soft drinks and ready-to-heat products such as pizza, instant soup, hot dogs and chicken nuggets. In short – a list of wrappers you might find on the floor of a teenager's room.

"Ultra-processed foods are typically high in sugar, sodium (and) trans and saturated fats, are energy-dense and are low in fiber and micronutrients," said lead researcher Dr. Zefeng Zhang, an epidemiologist at the Centers for Disease Control and Prevention in Atlanta. A high-sodium diet is associated with high blood pressure. Eating trans fats and saturated fats has been associated with increased risk for heart disease.

Zhang led research reported last year showing that U.S. adults get more than half of their daily total calories from ultra-processed foods, with a corresponding decrease in heart health. The new work focused on adolescents.

Researchers looked at 5,565 people ages 12 to 19 taking part in a large national survey. Their diet was compared with how they fared on a list of heart-health categories known as the American Heart Association's Life's Simple 7. It includes measures of weight, high blood pressure, diabetes and more.

The results showed adolescents eat even more ultra-processed food than adults: nearly 66% of their calories came from such foods, compared to about 55% for adults.

The adolescents' choices correlated with worse heart health. For every 5% increase in the number of calories they got from ultra-processed food each day, their score on a 12-point scale of heart health declined by 0.13 points.

Put another way, Zhang said, "higher consumption of ultra-processed foods might increase the risk of developing cardiovascular disease in the long-term among adolescents."

The research, presented this month at the AHA's virtual Scientific Sessions conference, is considered preliminary until published in a peer-reviewed journal.

Dr. Amanda Marma Perak, an assistant professor of pediatrics and preventive medicine at Northwestern University Feinberg School of Medicine in Chicago, said the findings were striking – adolescents consumed 42% to 88% of their calories from ultra-processed food.

"That leaves very little room for all of the healthy foods that provide nutrients teenagers really need – vegetables and beans, fruits, whole grains, unprocessed meats and fish, and plain low-fat milk and yogurt," said Perak, who was not involved in the study.

Part of the problem, Zhang said, is that it's easy for anyone to overeat foods that are engineered to be tasty. "People may eat more of these foods, even when they are no longer hungry. In addition, since ultra-processed foods often lack fiber, these foods may not make people feel as full as less-processed foods would."

Perak, who is also a pediatric preventive cardiologist at the Ann & Robert H. Lurie Children's Hospital of Chicago, had simple advice for adolescents: "Eat real food" – things that look as close to the way they did in nature as possible.

Healthy alternatives can still be convenient as well as delicious. For example, she said, instead of a packaged granola bar, a teen could choose unsalted nuts and a piece of whole fruit as a snack. "That's just as easy to grab and eat on the go, but much more filling and nutritious."

Parents can help by involving kids early in preparing meals and snacks. "Help them learn how to use real foods to make simple meals that you can eat together as a family, and make sure you as parents are eating real food and modeling that for your kids," Perak said.

Keep healthy foods on hand for teens to easily grab, she said, and "if the family's going to have dessert, then make it yourselves from real food ingredients."

But responsibility for the problem shouldn't fall just on teens and their parents, Perak said.

"We as a society need to do better with making the healthy choice the easy choice, the affordable and accessible choice no matter what neighborhood you live in," she said. "And we need to do better protecting our vulnerable kids from the heavy marketing of ultra-processed food."

Find more news from Scientific Sessions.

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