Reducing kids' exposure to a variety of allergens, rather than targeting a single 'trigger,' might be a better way to avoid asthma, suggests a review of studies.
While some kids are genetically predisposed to developing the disease, parents might still be able to prevent or delay the onset of symptoms by minimizing exposure to likely allergens.
Review author Tanja Maas said: "Breastfeeding and house dust mite reduction seemed to be the most important interventions," used in the studies. The food interventions focused on hydrolyzed formula as opposed to regular formula. The use of hydrolyzed formula was not shown to have any preventive effect. Breastfeeding, however, seemed to be very effective."
Led by Maas, a researcher of immunological disease at Maastricht University Medical Center, in the Netherlands, the authors analyzed nine studies.
They classified three of the studies as multifaceted, taking more than one approach to asthma prevention. These studies covered both inhalant and dietary types of allergen reduction, while the remaining six studies looked at one type of allergen reduction alone.
Dietary restrictions started in pregnancy or from the child's birth. In studies that included a dietary approach, mothers were encouraged to breastfeed or use special formula and to delay the introduction of solid foods into the child's diet.
Environmental interventions included the reduction of dust mites, pet allergens and exposure to tobacco smoke in the child's immediate environment.
The majority of allergic sensitization probably happens in early childhood or adolescence.
"We see most seasonal allergy sensitization occur by five years of age. Eighty percent of food allergies are present by two to three years of age," said paediatric allergist Harvey Leo, M.D., an assistant research scientist at the Center for Managing Chronic Disease at the University of Michigan.
The review appears in the current issue of The Cochrane Library, a publication of The Cochrane Collaboration.