BACKGROUND:

Although several studies have investigated the influence of diet on asthma in schoolchildren, none of them has evaluated how obesity can modify this effect. A study was undertaken to evaluate the association of various foods and a Mediterranean diet with the prevalence of asthma and rhinoconjunctivitis, adjusting for obesity and exercise.

METHODS:

A cross-sectional study was performed in 20 106 schoolchildren aged 6-7 years from eight Spanish cities. Using the ISAAC phase III questionnaire, parents reported chest and nose symptoms, food intake, weight, height and other factors, including exercise. A Mediterranean diet score was developed. A distinction was made between current occasional asthma (COA) and current severe asthma (CSA).

RESULTS:

Independent of the amount of exercise, each Mediterranean score unit had a small but protective effect on CSA in girls (adjusted OR 0.90, 95% CI 0.82 to 0.98). Exercise was a protective factor for COA and rhinoconjunctivitis in girls and boys (the more exercise, the more protection). Obesity was a risk factor for CSA in girls (adjusted OR 2.35, 95% CI 1.51 to 3.64). Individually, a more frequent intake (1-2 times/week and>or=3 times/week vs never/occasionally) of seafood (adjusted ORs 0.63 (95% CI 0.44 to 0.91) and 0.53 (95% CI 0.35 to 0.80)) and cereals (adjusted OR 0.56 (95% CI 0.30 to 1.02) and 0.39 (95% CI 0.23 to 0.68)) were protective factors for CSA, while fast food was a risk factor (adjusted ORs 1.64 (95% CI 1.28 to 2.10) and 2.26 (95% CI 1.09 to 4.68)). Seafood (adjusted ORs 0.74 (95% CI 0.60 to 0.92) and 0.67 (95% CI 0.53 to 0.85)) and fruit (adjusted ORs 0.76 (95% CI 0.60 to 0.97) and 0.71 (95% CI 0.57 to 0.88)) were protective factors for rhinoconjunctivitis.

CONCLUSIONS:

A Mediterranean diet has a potentially protective effect in girls aged 6-7 years with CSA. Obesity is a risk factor for this type of asthma only in girls.