Before you bite into that Big Mac, take a deep breath—because deep breaths could be harder to come by if you're indulging in fast food more than three times a week. New research from New Zealand, published in Thorax: An International Journal of Respiratory Medicine, has found an association between high fast-food intake and asthma among children.
The researchers compiled survey data on food intake for 319,196 13- to 14-year-olds and 181,631 6- to 7-year-olds, and compared that with diagnoses for asthma, eczema, and nasal allergies.
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In both cases, eating fast food more than three times a week was associated with a higher prevalence of asthma, while eating fruits and vegetables at least three times a week was associated with lower rates. In the teenagers, asthma was also associated with higher consumption of butter, margarine, and pasta, though to a lesser degree than with fast food.
"What this study says is that we kind of are what we eat," says Todd Mahr, MD, chair of American Academy of Pediatrics' section on allergy and immunology and a doctor with a private practice at Gundersen Health System in LaCrosse, WI. Dr. Mahr wasn't involved with the study. "I don't want parents thinking if we eat fast food three times a week, Johnny's going to develop asthma," he says, but he adds that it's an intriguing study that should get doctors and parents alike thinking more about how a child's diet affects his or her respiratory health—an association not many people make.
There is plenty of evidence to suggest that children suffering from obesity are at a higher risk of developing asthma, Dr. Mahr says. The two conditions are thought to be linked because both are characterized by high levels of inflammation. But this study controlled for obesity and still saw an association between high fast-food intake and asthma. The authors point to previous studies showing an association between increased asthma risk and trans fats (which are known to promote inflammation) as well as sugar—and there's no shortage of either in fast food. And they suggest that it's the antioxidants and other biologically active compounds in fruits and vegetables that protect against allergic diseases, like asthma. But Dr. Mahr says those studies are too preliminary to explain what might be going on here.
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In his own practice, he's seen patients whose asthma or non-food-related allergies improve when he has them consult a nutritionist, he says. "More doctors and researchers are looking at the environment as a whole," he says. "We've looked at smoking, we've looked at off-gassing volatile organic compounds [chemicals emitted by glues, furniture finishes and other household products], and now people are looking into diet. We're starting to realize that everything that goes into the body may have an effect on a person."
The bottom line? Feeding your children, and yourself, a healthier diet isn't going to hurt, and it may prevent diseases you wouldn't normally associate with food—whether it's asthma or a bad case of hay fever.