Teens are notoriously poor eaters. Of course, each teen is different, but it's not uncommon for teens to eat a lot of fast food and to make less than sensible food choices.
Specifically, foods with anti-oxidants and other anti-inflammatory nutrients, including fruit, vitamin E, and omega-3 fatty acids, tend to improve breathing. Teens who don't get them in their normal diets may be more breathless.
The study, done by the Harvard School of Public Health, examined 2,112 12th-grade students from 12 communities around the U.S. and Canada over the course of a year. Most of the teens in the study were white, about a third were overweight and hardly any of them took multivitamins.
It might be overstating to say "An apple a day will keep asthma [and the doctor] away," but it is fair to say that teens would benefit from making healthier food choices.
"A balanced diet is not only good for lung health, but for general health," said Mark J. Rosen, MD, FCCP, President of the American College of Chest Physicians. "Parents and physicians should work together to monitor and maintain healthy diets and lifestyles for children of all ages."