March 6 (HealthDay News) -- Teenage junk-food addicts aren't doing their bodies any favors, and their lungs are no exception.
Researchers have found that diets lower in fruit, vitamins C and E, and omega-3 fatty acids are associated with lower pulmonary function in adolescents.
Jane S. Burns, a research associate at the Harvard School of Public Health in Boston, said the clinical effects may not be obvious to teens or their doctors. "However, it is a matter for concern, because it suggests these children are not developing their optimal, potential lung function," she said. "Later in life, this may have an effect, as lower lung function is linked with earlier morbidity and mortality."
What's more, several studies have reinforced the importance of fruit and antioxidants in the diet for reducing wheeze among asthmatic children, Burns added.
Adolescence is a period of rapid physical change, so it should be no surprise that teens require additional nutrients to grow, develop and stay healthy.
Potato chips and cookies are OK once in a while, says TeensHealth, a project of the Nemours Foundation. But the best choices are whole or unprocessed foods, such as fresh fruits and vegetables, whole grains, low-fat dairy products, lean meats, fish and poultry.
Christine Karpinski, a sports nutritionist in West Chester, Pa., says that certain nutrients, including those found in fruits and fish, are thought to protect the lungs from cell and tissue damage caused by inflammation.
"The lung contains many inherent antioxidant defenses to combat this," she said. "However, there may be an increased need for these nutrients with asthma."
To find out how diet affects lung function in teens, researchers examined data from more then 2,000 12th-grade students in the United States and Canada. The students took lung-function tests and answered questions about their respiratory health.
Eating less than a quarter of a serving of fruit a day was linked to lower-than-average lung function and a greater incidence of chronic bronchitis symptoms and asthma.
Low intake of omega-3 fatty acids, such as those found in fish, was associated with an increased likelihood of chronic bronchitis symptoms, wheeze and asthma.
Teens who smoked and who had lower vitamin C intake had greater odds of respiratory symptoms than did smokers who had consumed more vitamin C.
"Smoking still remains one of the greatest threats to both respiratory and general health, and health messages geared toward teenagers should also focus on smoking prevention and cessation," Burns said.
"That being said," she added, "adolescents in this country do not consume adequate amounts of important nutrients, which we think has deleterious effects on respiratory health."
The federal government's Dietary Guidelines for Americans, updated in 2005, increased the recommended intake of fruits and vegetables from five servings a day combined to nine servings a day -- or 2 cups of vegetables and 2 cups of fruit, Karpinski noted.
SOURCES: Jane S. Burns, Sc.D., research associate, Harvard School of Public Health, Boston; Christine Karpinski, M.A., R.D., L.D.N., C.S.S.D., board-certified specialist, sports nutrition, Nutrition Edge Inc., West Chester, Pa.; TeensHealth, Nemours Foundation; U.S. Department of Health and Human Services