Allergen avoidance in infancy and allergy at 4 years of age

Is asthma prevention possible with dietary manipulation?

What we know: Primary prevention of asthma should be possible because the recent increase in asthma is due to environmental factors. The major modifiable dietary environmental risk factors for childhood asthma are lack of breastfeeding and low intake of omega-3 fatty acids. Randomised controlled trials (RCTs) have shown that interventions using probiotics, hydrolysed milk formulas, and combined dietary manipulation plus airborne allergen avoidance reduce asthma and/or atopy in newborns. Observational studies have shown a 30%-50% reduction in childhood asthma with exclusive breastfeeding for three months, and similar reductions in children who eat fish regularly (ie, have a high intake of omega-3 fatty acids). What we need to know: Will further RCTs using intervention with probiotics reveal identifiable subgroups of children who respond and children who do not respond? Will supplementation of the diet with omega-3 oil reduce the rate of significant clinical atopic disease, particularly asthma? If so, for how long will supplements need to be given? Will effective primary prevention require multiple intervention strategies? If so, how feasible are these as public health interventions? What are the benefits and harms of allergen-avoidance diets in high-risk women who are breastfeeding? Can protein hydrolysate formulas reduce rates of atopy and/or asthma?

Is prevention of childhood asthma possible? Allergens, infections and animals

What we know: Epidemiological studies have identified a number of factors associated with increased incidence of asthma. These include allergen sensitisation and exposure, reduced exposure to infections and to farm animals in early childhood, and maternal smoking. These factors may represent "true" risk factors for asthma or may be merely associated factors that do not in themselves cause asthma. The "hygiene hypothesis" has been proposed as one mechanism by which infections may protect against asthma. Current recommendations for the primary prevention of asthma include exclusive breastfeeding for the first six months of life, avoidance of maternal smoking during pregnancy and infancy, and reducing the levels of house-dust mite in some environments. What we need to know: What are the mechanisms by which specific risk factors and prevention strategies lead to or protect from asthma? How do genetic and environmental factors interact to increase the risk of asthma?