A "Mediterranean" diet rich in fruits, vegetables and nuts protects against allergic rhinitis and asthma symptoms, suggests research published ahead of print in Thorax.
The researchers assessed the dietary habits, respiratory symptoms, and allergic reactions of almost 700 children living in four rural areas on the Greek island of Crete.
The children were all aged between 7 and 18 years of age.
Skin allergies are relatively common in Crete, but respiratory allergies, such as asthma and allergic rhinitis are relatively rare.
Parents completed detailed questionnaires on their children's allergic and respiratory symptoms and dietary habits.
Whether the children ate a "Mediterranean" diet was measured against a set of 12 foodstuffs, including fruits, vegetables, whole-grains, legumes, nuts, and olive oil.
Eight out of 10 children ate fresh fruit, and over two thirds of them ate fresh vegetables, at least twice a day.
The effect of diet was strongest on allergic rhinitis, but it also afforded protection against asthma symptoms and skin allergy.
Children who ate nuts at least three times a week were less likely to wheeze.
Nuts are a rich source of vitamin E, the body's primary defence against cellular damage caused by free radicals. And they contain high levels of magnesium, which other research suggests, may protect against asthma and boost lung power.
And a daily diet of oranges, apples, and tomatoes also protected against wheezing and allergic rhinitis.
Grapes in particular seemed to protect against current and previous wheezing and allergic rhinitis, even after adjusting for other potentially influential factors.
Red grape skin contains high levels of antioxidants as well as resveratrol, a potent polyphenol, known to curb inflammatory activity, say the authors.
But high consumption of margarine doubled the chances of asthma and allergic rhinitis, the findings showed.