THURSDAY, June 3 (HealthDay News) -- Children who eat three or more hamburgers a week may raise their odds for asthma and wheeze, a new study suggests.

However, eating the so-called "Mediterranean diet" -- rich in fruits, vegetables and fish -- could cut kids' respiratory risk, the researchers say.

"Our results support previous reports that the adherence to a Mediterranean diet, which is characterized by a high intake of fruit, vegetables and fish and a low intake of meat, burger and fizzy drinks, may provide partial protection against asthma in childhood," said lead researcher Dr. Gabriele Nagel, from the Institute of Epidemiology at Ulm University in Germany.

The report is published in the June 3 issue of Thorax.

For the study, Nagel's team collected data on about 50,000 children from 20 rich and poor countries. Parents were asked about their children's typical diet and whether they had asthma or not. In addition, almost 30,000 of the children were tested for allergies.

While diet did not appear to influence allergies, it was associated with the risk of asthma and wheeze, the researchers found.

Children in both rich and poorer countries who ate a lot of fruit had lower rates of wheeze.

Eating lots of fish seemed to protect children in rich countries, and a diet high in cooked green vegetables protected children in less developed countries from wheeze, Nagel's group found.

Fruits and vegetables are rich in antioxidant vitamins and biologically active agents, and the omega 3 fatty acids prevalent in fish have anti-inflammatory properties, which might explain these findings, the researchers said.

"Overall, a Mediterranean diet was associated with a lower lifetime prevalence of asthma and wheeze," Nagel said.

On the other hand, children who ate a lot of burgers had a higher lifetime prevalence of asthma and wheeze, the researchers found. The finding was especially true for allergy-free children from more affluent countries.

But the burger finding could be a marker for other lifestyle factors that could boost a child's for asthma, the researchers note. Meat in general was not seen to increase the risk of wheeze, the study found.

Pulmonologist Dr. Michael Light, a professor of medicine at the University of Miami Miller School of Medicine, agreed that diet can influence asthma.

"The data is fairly consistent that antioxidants and unsaturated fatty acids play a role in the big picture," Light said. "This doesn't mean if you change your diet today you are going to cure your asthma. All the study is saying is that one of the explanations for asthma is probably related to diet," he said.

Echoing these findings, results of a study presented May 16 at the American Thoracic Society International Conference in New Orleans showed that fatty meals were linked to impaired lung function.

In that study, Australian researchers tested people with asthma before and after a high-fat meal or after a low-fat meal. They found that the high-fat meal increased inflammation and reduced lung function.

"If these results can be confirmed by further research, this suggests that strategies aimed at reducing dietary fat intake may be useful in managing asthma," the study's lead author, Lisa Wood, a lecturer in biomedical sciences and pharmacy at the Hunter Medical Research Institute in New Lambton, said at the time.

More information

For more information on asthma, visit the U.S. National Institutes of Health.