Children who are genetically vulnerable to asthma may be less likely to develop the disease if their exposure to a variety of allergy triggers can be limited, a research review suggests.

Children with a family history of allergies and asthma are at increased risk of developing the conditions themselves. Asthma attacks, which are marked by inflammation in the airways, are often a response to allergens and irritants like cigarette smoke, pollen and dust mites.

The new review looked at nine clinical trials testing ways to prevent asthma in genetically susceptible children. Researchers found that efforts to shield children from multiple allergens at once helped lower the odds of their developing asthma.

In contrast, prevention that focused on only one allergy trigger at a time was ineffective, the investigators report in the Cochrane Database of Systematic Reviews, part of the Cochrane Library.

The implication for parents is that it is best to try to limit high- risk children’s exposure to all potential allergens in the environment, according to lead researcher Dr. Tanja Maas of the Care and Public Health Research Institute in Maastricht, the Netherlands.

That, she told Reuters Health, includes keeping children’s surroundings clear of tobacco smoke, furry pets and dust mites. The latter can be controlled by regular household cleaning and keeping the home free of dust traps like curtains, pillows and “cuddly” toys, Maas noted.

Breastfeeding for as long as possible may also be important, according to the researcher. In fact, there was evidence that breastfeeding and dust-mite avoidance were the two most effective measures against asthma development - though those results are not definitive.

It’s not clear why breastfeeding may help prevent later allergies and asthma, but it may be related to its benefits on immune system development, and because it delays the introduction of cow’s milk proteins into babies’ diets.

SOURCE: Cochrane Database of Systematic Reviews, online July 8, 2009.