When should solids be introduced to reduce the risk of allergy?

The current recommendation of delaying solids till 6 months continues to be challenged.  ESPGHAN  recommends introducing solids between 17 weeks (4 months) and no later than 26 weeks ( 6 months), depending on the infants developmental needs (1). This position is supported by a recent paper authored by Australian and New Zealand doctors who also question current recommendations in the context of the rising rates of food allergies in early childhood (2).

This paper makes the following points in support of introducing solids from around 4 months while maintaining breast feeding for at least 6 months:-

• Despite the belief that delaying solids till 6 months will reduce the risk of allergies (because of the increased permeability and immaturity of the infant’s gut mucosa), rates have increased.
• Prevention of allergy depends on acquiring immune tolerance, an early developmental process occurring in response to regular exposure of a food allergen or antigen. It coincides with the growth of healthy gut bacteria which influence the immune response. Continued breast feeding while introducing new foods may also promote tolerance. The ‘critical window’ for allergen/antigen exposure for development of immune tolerance is between 4-6 months. Exposure before or beyond this time may decrease tolerance. 
• Infants at high risk of allergies may require more regular and larger doses of food allergens to induce immune tolerance.
• Any benefit from early food allergen avoidance appears to be in the first 3-4 months.  There is little evidence that avoiding foods beyond this age reduces allergy risk.
• There is no strong evidence to support the association between early solid feeding and the development of asthma, eczema and food allergy.
• Breastfeeding exclusively to 6 months may compromise growth and development and may affect food and taste acceptance. It has also been linked to iron, iodine, zinc and other nutrient deficiencies

References:

1. Agostini C, Decsi T, Fewtrell M  et al. Complementary Feeding: A Commentary by the ESPGHAN Committee on Nutrition.  J Pediatr Gastroenterol Nutr 2008;46(1):99-110

2. Prescott SL, Smith P, Tang M et al. The importance of early complementary feeding in the development of oral tolerance: concerns and controversies. Paediatr Allergy Immunol 2008. Online article DOI: 10.1111/j.14399-3038.2008.00718.x