Certain allergenic foods introduced to an infant’s diet while weaning appear to reduce the chance of developing food allergies. This high quality review, including studies published this year, suggests that historical recommendations to delay the introduction of peanut and other allergenic foods to infant child’s diet in the first year of life may have been mistaken.
The methodological limitations in some studies included in this review, reduce our certainty in the degree of benefit, but as more high quality studies are undertaken the benefits and practicalities of how to introduce these foods are likely to become clearer.
The causes of food allergies are not fully understood and the number of people with food allergies and coeliac disease is rising in the UK. Current NHS advice is that potentially allergenic foods can be introduced one-by-one during weaning to check for any allergic reaction, but advice is under review.
A previous trial in high-risk infants without peanut allergy, included in this review, confirms that regularly eating peanuts from an early age can prevent peanut allergy.
Why was this study needed?
Around 10 people a year die from allergic reactions to foods in the UK. Although not everyone has such serious and dangerous reactions, many people live with the daily stress of managing their food allergies and any reactions they suffer.
Coeliac disease is not an allergy, but is caused by the body identifying gluten in wheat as a threat and attacking it. It causes diarrhoea, pain and discomfort, which can be severe, and affects around 1 in 100 people in the UK.
The number of people with food allergies and coeliac disease is rising – around 6-8% of children have a food allergy – and no-one is exactly sure why. For example, there has been a lot of debate about when to introduce potentially allergenic foods into children’s diets.
This systematic review looked at a range of foods and sought evidence on the link between the introduction of potentially allergenic foods and development of food allergies or coeliac disease.
What did this study do?
This systematic review and meta-analysis included randomised controlled trials and observational studies (such as cohort studies). It investigated whether the timing of introducing potentially allergenic foods affected the likelihood of children developing food allergies or coeliac disease.
For allergies there were 24 intervention studies (13,298 participants) and 69 observational studies (142,103 participants). For coeliac disease there were five intervention studies (5,623 participants) and 48 observational studies (63,576 participants). 26 of the included studies were UK-based.
Most of the included studies did not have a serious risk of bias. There was concern about the number of people dropping out and why that was happening, and how potential confounding factors from observational studies were accounted for in data analysis. There was a serious risk of bias amongst studies looking at eczema and wheeze related to introducing cow’s milk. These risks of bias affect our confidence in the findings for these foods.
What did it find?
- Introducing egg from four to six months was associated with a reduced likelihood of developing egg allergy than later on (risk ratio [RR] 0.56, 95% confidence interval 0.36 to 0.87, 5 trials including 1,915 participants). This could mean 24 fewer people with egg allergy per 1,000 population (assuming that 54 in 1,000 people have this allergy).
- Early peanut introduction from four to 11 months was associated with a reduced chance of developing peanut allergy (RR 0.29, 95% CI 0.11 to 0.74, 2 studies including 1,550 participants). This could lead to 18 fewer cases of peanut allergy per 1,000 population (assuming that 25 in 1,000 people have this allergy).
- Introducing milk early was not associated a milk allergy (RR 0.76, 95% CI 0.32 to 1.78, 2 studies including 1,550 participants).
- The timing of gluten introduction was not associated with the risk of developing coeliac disease (RR 1.22, 95% CI 0.81 to 1.83, 4 studies including 1,822 participants).
What does current guidance say on this issue?
2008 NICE guidelines recommend that babies are breast-fed or given infant formula for the first six months of their lives. When introducing solid foods, advice on the NHS Choices website suggests that foods babies could be allergic to – such as those containing cows’ milk, eggs, wheat, gluten, nuts, peanuts, peanut products, seeds, fish and shellfish – should be introduced in small quantities and one at a time to check for allergy.
People with a family history of eczema, asthma or hay fever are advised to speak to their GP or health visitor before introducing peanuts and peanut products.
What are the implications?
This systematic review was undertaken as part of a wider programme of work to inform UK infant feeding guidance that the Food Standards Agency will produce.
Though these findings broadly support current NHS advice that potentially allergenic foods do not need to be avoided, the new benefits of the introduction of these foods have not yet been fully considered in advice and guidance.
The studies included in this review had some limitations which mean that a broad consideration of a number of other sources of evidence will be required before recommendations to change of practice are made.
Citation and Funding
Ierodiakonou D, Garcia-Larsen V, Logan A, et al. Timing of Allergenic Food Introduction to the Infant Diet and Risk of Allergic or Autoimmune Disease: A Systematic Review and Meta-analysis. JAMA. 2016;316(11):1181-1192.
This work was funded by the UK Food Standards Agency and supported by the National Institute for Health Research Imperial Biomedical Research Centre and the MRC-Asthma UK Centre in Allergic Mechanisms of Asthma. Dr Trivella was supported by Cancer Research UK.
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