The Role of Complementary Feeding in Food Allergy Prevention

Allergies & Immunity

19 min watch

Complementary feeding plays a critical role in the prevention of food allergy, and the evidence in this area has evolved considerably over the past decade. Historically, the advice to parents of infants at high risk of allergy was to delay the introduction of allergenic foods including peanut, egg, and tree nuts until after the first year of life. However, large well-designed clinical trials have shown that delaying introduction can increase the likelihood of developing food allergy, whereas early, exposure during a defined window of immune development promotes oral tolerance.

Author(s):

Rosan Meyer

“The Learning Early About Peanut Allergy” (LEAP) study, published in 2015, demonstrated that in high-risk infants—defined as those with severe eczema and/or egg allergy—the introduction of peanut-containing foods between four and eleven months of age lead to a prevalence of peanut allergy at 60 months of age to 1.9% in the consumption group versus 13.7% in the avoidance group. This level or reduction has been maintained at 12 years of age.[2] After this cam the “The Enquiring About Tolerance” (EAT) study which explored the early introduction of multiple allergens, including peanut, egg, cow’s milk, sesame, whitefish, and wheat from after three months of age in a general breastfed population. Although adherence was a challenge, per-protocol analysis suggested a reduced risk of allergy with early introduction, particularly for peanut and egg.[3]

Furthermore, there is conflicting data on the early exposure of cow’s milk formula and whether this leads to the development of this allergy or whether this is preventative. [4] The timing and whether this is repeatedly ingested, seems to be key in this debate.[5]

International guidelines have shifted accordingly and are summarised in Table 1 below.

Beyond allergens, a diverse diet in the first year appears to support a healthy gut microbiota, which may contribute to tolerance development. Breastfeeding should be encouraged until around six months where possible and continued alongside solids thereafter; ongoing breastfeeding during allergen introduction may confer additional tolerance benefits.[6] Adequate intake of nutrients such as vitamin D and omega-3 fatty acids, as well as prebiotic fibre, may also support immune regulation, although the evidence in these areas is still emerging.
In summary, complementary feeding is no longer simply about meeting nutritional needs but is also a powerful tool for allergy prevention. Early and regular exposure to common allergenic foods, within the developmental window of four to six months, is both safe and effective, particularly for high-risk infants. Healthcare Professionals should be confident in providing parents with practical, evidence-based guidance on how and when to introduce these foods, reinforcing that once introduced, regular ingestion is essential for maintaining tolerance. The shift from avoidance to early introduction represents one of the most significant changes in infant feeding advice in recent decades, with the potential to reduce the burden of food allergy in the next generation.

EAACI Guidelines 2021

UK Guidelines 2018

AAAAI Guidelines 2021

ASCIA Guidelines 2019

Suggests introducing well-cooked hen's egg, but not raw egg or uncooked pasteurized egg, into the infant diet as part of complementary feeding.

In populations where there is a high prevalence of peanut allergy, suggests introducing peanuts into the infant diet in an age-appropriate form as part of complementary feeding.

Infants with eczema and/or an existing food allergy may benefit from the introduction of foods containing egg and peanut from 4 months alongside other complementary foods

Introduce peanut-containing/egg or egg containing products to all infants, irrespective of their relative risk of developing peanut allergy, starting around 6 months of life, though not before 4 months of life.

Introduce peanut and egg in the first year of life in all infants, regardless of their allergy risk factors.

References

Soriano, V.X., et al., Complementary and Allergenic Food Introduction in Infants: An Umbrella Review. Pediatrics, 2023. 151(2).
Du Toit, G., et al., Follow-up to Adolescence after Early Peanut Introduction for Allergy Prevention. NEJM Evid, 2024. 3(6): p. EVIDoa2300311.
Perkin, M.R., et al., Randomized Trial of Introduction of Allergenic Foods in Breast-Fed Infants. N Engl J Med, 2016. 374(18): p. 1733-43.
Ulfman, L., et al., Relevance of Early Introduction of Cow's Milk Proteins for Prevention of Cow's Milk Allergy. Nutrients, 2022. 14(13).
Herman, K., et al., Prevention of IgE-Mediated Food Allergy: Emerging Strategies Through Maternal and Neonatal Interventions. J Allergy Clin Immunol Pract, 2024.
12(7): p. 1686-1694.
Venter, C., Immunonutrition: Diet Diversity, Gut Microbiome and Prevention of Allergic Diseases. Allergy Asthma Immunol Res, 2023. 15(5): p. 545-561.