Current suggestions

The following suggestions for pre and postnatal feeding of infants who may be genetically predisposed to asthma are based on the evidence discussed in this paper, and current NHMRC and WHO guidelines for the general population.

1 Antigen avoidance diets during pregnancy should be avoided as they may have an adverse effect on maternal and/or foetal nutritional status.

2 Mothers should be advised to breastfeed exclusively for the first 6 months of life.

3 If a mother is unable or does not wish to breastfeed, suggest a partially hydrolysed formula for the first 6 months of life. Such formulas are available from most pharmacies and supermarkets.

4 Consider suggesting that pregnant women consume foods or supplements containing omega-3 fatty acids and Lactobacillus, that breastfeeding women consume foods or supplements containing Lactobacillus and that infants aged 6 months or more are given supplementary omega-3 fatty acids.

5 After 6 months of age other foods may be gradually introduced into a baby’s diet. Likely allergens such as cow’s milk and other dairy products, soya products, nut-containing spreads (such as peanut butter) and fish should not be introduced in the first year.

It is important to note that even if these suggestions are carried out, there is still a significant risk that high-risk infants will develop asthma.

Primary prevention, diet and asthma

The increase in the prevalence of allergy-related asthma over the last two decades, and recognition that the increase may have resulted from environmental changes,^1-3have highlighted the need for further investigation of primary preventive strategies in high-risk infants (eg infants with a family history of atopic disease or asthma).³

Early allergic sensitisation has been associated with later development of asthma.^2-4 Dietary measures are therefore being investigated with the aim of learning more about modifiable factors involved in the “atopic march” from sensitisation to food allergens (associated with food allergy and eczema) to sensitisation to aeroallergens (with subsequent development of asthma and allergic rhinitis).

Allergen avoidance

Dietary interventions have largely focussed on avoidance of food allergens (eg exclusive breastfeeding, maternal avoidance of allergens during lactation and use of hydrolysed formulae). These approaches have shown some reductions in the development of atopy^5-10 and of asthma.^11-19 However, it remains uncertain whether the onset of asthma is prevented or merely delayed.

Polyunsaturated fatty acids and probiotics

Recent findings suggest that, as well as allergen avoidance, dietary supplementation may have a role in preventing or delaying the onset of asthma.

The role of polyunsaturated fatty acids in the development of atopic diseases and in diminishing the inflammatory response is being examined.^20-26
Studies have also highlighted the involvement of the intestinal microflora in the development of atopic disease and the potential for probiotics to provide protection.^27-31

These areas require further investigation but have shown some promising initial results.^32-34

It is important to make the distinction between the use of dietary measures for the primary prevention of asthma and their use in secondary prevention of symptoms in people with established asthma.