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. Skin allergies are relatively common in Crete, but respiratory allergies, such as asthma and allergic rhinitis are relatively rare.

For the study, parents completed detailed questionnaires on their children’s allergic and respiratory symptoms and dietary habits. The children were all aged between 7 and 18 years of age. 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 study found that 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 defense against cellular damage caused by free radicals, and they contain high levels of magnesium, which other research suggests might protect against asthma and boost lung power. The study also found that 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.

The findings also found foods that can negatively impact breathing. High consumption of margarine doubled the chances of asthma and allergic rhinitis, the study showed.