Researchers in Sydney, Australia, have just published the results of a five-year study into dust mites and infant diets, and whether such factors could trigger asthma and other allergic responses in children. Published in the Journal of Allergy and Clinical Immunology, the study was designed specifically to test house dust mite (HDM) avoidance and dietary fatty acid modification as interventions to prevent asthma and allergic disease in children with a family history of asthma and wheezing. The research involved tracking newborn children with a family history of asthma from their birth to the age of five. Unfortunately, it was found that avoiding house dust mite allergens from birth does not prevent the onset of asthma, eczema or atopy in high-risk children. And modifying a child's diet to increase the consumption of omega-3 fatty acids (found in high concentrations in oily fish) was also found to be ineffective in preventing the onset of asthma.
Parents in the study testing house dust mite avoidance were instructed to use both physical and chemical methods to reduce their child's exposure to HDM allergens, including changes to bedding materials and the addition of a benzyl benzoate-containing solution to the wash at regular intervals. While the HDM avoidance strategy resulted in a reduction of allergen concentrations in the house, it did not reduce the rate of asthma, wheeze or atopy.
The dietary intervention was intended to increase the proportion of omega-3 fatty acids consumed in a diet and reduce the content of omega-6 fatty acids. Parents were provided with cooking oils and margarine high in omega-3 fatty acids to use in food preparation and food oil capsules were added to the child's formula or to solid foods from the age of 6 months. While this change in diet did alter blood levels of fatty acids, the rate of asthma, wheezing, eczema or atopy did not differ between the groups who did and did not participate in the changed diet.
"We have shown it's possible to implement feasible strategies to reduce HDM allergen concentrations in a child's bed and create a sustained alteration in the ratio of fatty acids during the first five years of life," said Dr Guy Marks, the lead researcher. "However as special treatment of children's beds and giving fish oil supplements to very young children with a family history of allergic disease seemed to have little benefit for the prevention of asthma and atopy, at least in the short term, we now need to consider other possibilities."
But parents can at least take some comfort from the fact that their cleaning regime (or lack of it) is not to blame for their child's illness. "The study results help remove some of the blame parents often take on for not doing enough to prevent their child getting asthma," said Marks, in conclusion.
Source: Journal of Allergy and Clinical Immunology
