LONDON -- Eating fast food three or more times a week was linked to a higher risk of severe asthma and eczema in children, researchers have found.
Teens who ate three or more weekly servings had a 39 percent increased chance of developing severe asthma, while younger children had a 27 percent higher risk, according to a study of 319,000 teens in 51 countries and 181,000 children ages 6 and 7 in 31 countries. The research, led by scientists at the University of Auckland in New Zealand, was published in the British medical journal Thorax.
The study didn't prove that eating more fast food caused the increase in the conditions, which both can be linked to the overreaction of the body's immune system. Because fast food was the only category shown to have an association with the disorders, the results suggest that such a diet may cause asthma attacks or eczema outbreaks, the authors said. Fast foods contain high levels of trans fatty acids, which are known to affect immune reactions, they said.
"The positive association observed here between fast food intake and the symptom prevalence of asthma, conjunctivitis and eczema in adolescents and children deserved further exploration, particularly in view of the fact that fast food is increasing in popularity around the world," the authors said in the published study. They included scientists in New Zealand, Australia, Spain, Germany and Britain.
Conversely, eating three or more servings of fruit a week showed a protective effect, reducing flare-ups of the three conditions, the study found. The data came from developed countries including Canada as well as developing countries such as Nigeria and Brazil.
An almost fourfold increase in childhood obesity in the past three decades, twice the asthma rates since the 1980s, and a jump in the number of attention-deficit disorder cases are driving the growth of chronic illnesses, according to a 2007 study by researchers at Harvard University. An association between asthma and obesity supports the theory that sedentary behavior diminishes lung function, they said.