Diet and Asthma, Allergic Rhinoconjunctivitis and Atopic Eczema Symptom Prevalence: An Ecological Analysis of the International Study of Asthma and Allergies in Childhood (ISAAC) Data

August 2002
Wanda Phipatanakul

Abstract

Purpose of the Study. To provide a global analysis of prevalence rates of wheeze, allergic rhinoconjunctivitis, and atopic eczema in relation to diet, as defined by national food intake data.

Study Population. A total of 721 601 children of 2 age groups (6- to 7- and 13- to 14-year-olds) from 156 collaborating centers in 56 countries from the International Study of Asthma and Allergies in Childhood (ISAAC).

Methods. Symptom prevalence data was collected by video questionnaires assessing asthma symptoms and severity, allergic rhinoconjunctivitis symptoms, and atopic dermatitis symptoms. Using the 1995 food balance sheet and food supply data from the Food and Agriculture Organization (FAOSTAT) Web site, figures were compared of food and nutrient intake among the large number of countries in the ISAAC Phase One.

Food consumption per capita is calculated to determine per capita consumption of macro- and micronutrients as a percentage of total energy consumption. Symptoms of wheeze, allergic rhinoconjunctivitis, and atopic eczema symptom prevalence were regressed against the per capita food intake and adjusted for gross national product to account for economic development.

Results. The 13- to 14-year-old age group showed a consistent pattern of decreases in symptoms of wheeze (current and severe), allergic rhinoconjunctivitis, and atopic eczema, associated with increased per capita consumption of calories from cereal and rice, starch, and vegetable nutrients (vitamin A, E, protein, monounsaturated fatty acids, polyunsaturated fatty acids, and saturated fats).

The video questionnaire data for 13- to 14-year-olds and ISAAC data for 6- to 7-year-olds showed similar patterns for these foods. There was no association between monounsaturated fatty acid and polyunsaturated fatty acid intake. Olive oils showed a negative association with asthma, allergic rhinoconjunctivities, and atopic eczema, while soy oil consumption was associated with all 3 conditions.

Conclusions. A consistent inverse relationship was seen between prevalence rates of 3 allergic conditions and the intake of starch, cereals, and vegetables. If these findings could be generalized, and if the average daily consumption of these foods increased, it is speculated that an important decrease in symptom prevalence may be achieved.

Reviewer’s Comments. This is an interesting study that evaluates a large population of subjects to determine if there is any consistency between dietary intake of certain foods and the development of atopic disease. The authors suggest that perhaps by increasing the daily per capita amount of calories from cereal and rice that the prevalence of atopic disease could be decreased.

Additional study would be required to evaluate if there are certain substances in these foods that may have benefit. Until then, I am not sure that increasing intake of starch, cereals, and vegetables alone will play a significant role in decreasing the prevalence of atopy, and it is likely that other nondietary factors are also of importance.