Diet might play an important role in the development of asthma. Eating at fast-food outlets and having a low intake of vegetables and milk have been linked in a new study to an increased incidence of childhood asthma.
Professor Anthony Seaton (department of environmental and occupational medicine, Aberdeen university) and colleagues in Saudi Arabia compared risk factors for asthma in 114 patients with a history of asthma in the previous 12 months, with 202 controls. The study was carried out in Saudi Arabia in rural and urban locations. In rural locations, a traditional diet of vegetables, fruit, rice, milk, chicken and lamb is followed but in urban locations, an influx of western-type frozen and prepared foods in supermarkets and restaurants has occurred, the researchers say.
The results showed that family history of asthma, atopy and eating at fast-food outlets were significant risk factors for wheezy illness. Looking at dietary factors in detail, children with wheezy illness ate significantly less fibre, vitamin E, magnesium, calcium, sodium and potassium than controls. Vegetable consumption was an important factor, with children who ate less than two portions a day being 2.8 times more likely to have wheezy illness. Consumption of less than two "portions" of milk per day was associated with a risk ratio of 2.4.
The authors comment that this is the first study to investigate total diet as a risk factor for childhood asthma. Dietary factors are associated with a two- to three-fold increase in the risk of having symptoms, they say, adding that a change in diet may largely explain the increase in prevalence of these conditions in developed countries.
The researchers recommend that intervention trials should be considered. However, they caution that these should be based on an increase of fruit and vegetable consumption rather than supplementation because "a move away from the combination of different nutrients in the balanced diet with which we have evolved, rather than the exclusion or inclusion of particular micronutrients, has been responsible for the observed changes in disease prevalence" (Thorax 2000;55:775-9).

Eating fast food has been linked to increased incidence of childhood asthma