Timing of allergenic food introduction to the infant diet and risk of allergic or autoimmune disease: A systematic review and meta-analysis

Lerodiakonou D, Garcia-Larsen V, Logan A et al. (2016) JAMA 316: 1181-1192. http://jama.jamanetwork.com/article.aspx?articleid=2553447

In a nutshell

This large, comprehensive review found that early introduction of egg (from 4 to 6 months) or peanut (from 4 to 11 months) to infants was associated with a reduced risk of developing egg or peanut allergy.

Background

The prevalence of food allergies in the UK has doubled in the last decade (Allergy UK). This systematic review and meta-analysis was funded by the UK Foods Standards Agency to inform UK infant feeding recommendations regarding introduction of allergenic foods.

Study objective

To evaluate whether timing of introduction of allergenic foods (milk, egg, fish, shellfish, tree nuts, wheat, peanuts and soya) to the infant diet influences risk of developing allergic (wheeze, eczema, allergic rhinitis, food allergy, allergic sensitisation) or autoimmune (type 1 diabetes, celiac disease, inflammatory bowel disease, juvenile rheumatoid arthritis, psoriasis and vitiligo) disease.

Study design

The scientific literature was searched using systematic methods for intervention and observational studies published in the last 70 years that examined the relationship between infant age (up to 1 year) at introduction of allergenic food and the development of allergenic or autoimmune disease (at any age). Data from eligible studies was extracted and collated for meta-analysis. Risk of bias and the quality of the evidence (i.e. whether the evidence is convincing) were assessed using well-established methods.

Key results

The search identified 146 eligible studies on timing of introduction of allergenic foods, of which 93 evaluated allergic outcomes and 53 autoimmune outcomes. There were no studies on psoriasis or vitiligo. 

  • There was moderate quality evidence from five trials that egg introduction at 4 - 6 months of age was associated with a 44% reduced risk of egg allergy, compared to later egg introduction.
  • There was moderate quality evidence from two trials that peanut introduction at 4 -11 months of age was associated with a 71% reduced risk of peanut allergy, compared to later peanut introduction.
  • Timing of introduction to egg or peanut was not associated with reduced risk of allergy to other foods.
  • There was some suggestion that fish introduction before 6-9 months of age was associated with reduced allergic sensitisation and rhinitis, compared to later fish introduction, but the evidence was found to be of low or very low quality.
  • No evidence was found for an association between timing of introduction of other allergenic foods (milk, shellfish, tree nuts, wheat and soya) and risk of allergic disease.
  • No evidence was found for an association between timing of introduction of any allergenic foods and the risk of autoimmune disease.

Authors’ Conclusions

‘In this systematic review, early introduction of egg or peanut to the infant diet was associated with lower risk of developing egg or peanut allergy. These findings must be considered in the context of the limitation in the primary studies.’

Limitations

This comprehensive systematic review and meta-analysis on timing of introduction of allergenic foods used robust methodology. However, the evidence-base identified in relation to each specific allergenic food was found to limited to a small number of studies and there was significant variation in study methodologies and populations. While the evidence available on timing of egg and peanut introduction and allergy risk was found to be fairly convincing, more studies are required to confirm the findings and to determine the exact pattern and quantity of intake that results in the biggest reduction in allergy risk.

Relevance

The old advice to avoid peanut consumption during pregnancy, breastfeeding and early childhood no longer stands and since 2009 the Department of Health has recommended that high allergenic foods can be introduced from 6 months (n.b. nuts in their whole form should not be given to young children as they are a choking hazard). For infants at a high risk of foods allergy (e.g. those with a family history or with eczema), the advice is for parents to talk with a health professional before introducing allergenic foods into the diet. The data from this study raises the question of whether earlier introduction of allergenic foods might be beneficial for some infants and this will be considered by UK Food Standards Agency and the Scientific Advisory Committee on Nutrition in their on-going reviews of UK infant feeding guidance.