Life> Health

Mediterranean diet may not protect against asthma

(Agencies)
Updated: 2010-07-19 09:08

Countries on the Mediterranean might enjoy low asthma rates, but their typical diet shouldn't take the credit, suggests a new study.

"At the moment, we cannot give definitive advice about any protective effect of diet on asthma," said study co-author Dr. F.J. Gonzalez Barcala of the Hospital de Pontevedra in Santiago de Compostela, Spain. "But we are sure that more research is needed on the topic."

People have speculated that a diet rich in fish, fruits and vegetables, which is typical of countries surrounding the Mediterranean Sea, could help explain why asthma is so much less common in these places compared to other parts of the world. For example, less than 10 percent of Spanish 13- and 14-year-olds have the chronic lung disease, compared to nearly a quarter of similarly aged British kids.

Mediterranean diets vary, the study authors note, but generally involve more monounsaturated fats than saturated fats, lots of fish, vegetables, fruit, nuts, and grains, and minimal milk and dairy.

Studies have found that people who eat such diets tend to be healthier. But based on earlier conflicting studies and the inherent difficulty of linking diet to health, Gonzalez Barcala and his colleagues had suspicions that the protective effect of asthma wasn't as clear as it seemed.

The team set out to study nearly 15,000 children in their home Mediterranean country. They looked at the diets and asthma rates of Spanish boys and girls aged 6 to 7, and 13 to 14. Each kid was categorized into one of four groups reflecting the extent to which they reported adhering to the Mediterranean diet.

About 40 percent of the younger kids and 20 percent of the older kids had suffered from asthma at some point in their lives. The region studied is known to have particularly high asthma rates relative to the rest of Spain, Gonzalez Barcala noted in an email to Reuters Health.

With the exception of the 6- to 7-year-old girls, no relationships could be found between diet and asthma after accounting for obesity and family lifestyle. And among this group of young girls, greater adherence to the Mediterranean diet actually appeared to increase the risk of asthma.

This unexpected result was likely due to children -- or their parents -- altering their diet because they knew they had asthma, rather than the diet triggering the disease, the researchers report in the journal Pediatric Allergy and Immunology.

Even if diet is truly not a factor, researchers shouldn't stop looking to Mediterranean countries for clues about asthma, noted Dr. Richard Hooper, of the University of London, who has separately studied the link between asthma and diet.

"Asthma is much more common now than it was two generations ago, and that must have something to do with our environment or the way we live our lives," he told Reuters Health by email. "Identifying populations which have somehow avoided the asthma epidemic could help us identify what those factors are, but it's often difficult to tease out the competing explanations."

"For example, your diet may give clues to other lifestyle choices you make," Hooper added. "Across national borders, of course, there may be large cultural differences that go beyond diet."