Primary prevention
Current evidence does not support an antigen avoidance diet for high-risk women during pregnancy.[26][27]
Maternal antigen avoidance during lactation may reduce the likelihood of an infant developing eczema, or reduce the severity of eczema should it develop, but larger studies are necessary.[27]
Ante- and perinatal maternal supplementation with omega-3 polyunsaturated fatty acids (n-3 PUFA) may reduce prevalence of sensitisation to egg in children up to 12 months old; however, postnatal supplementation with n-3 PUFA has not been shown to prevent allergic disease.[28][29][30]
In infants at high risk for developing allergy, there is no need to avoid complementary food introduction beyond 4 months of life.[31] In 2017, a US National Institute of Allergy and Infectious Diseases expert panel published revised guidance for preventing peanut allergy in infants at high risk (i.e., those with severe eczema, egg allergy, or both).[23] The expert panel concluded that, subsequent to the findings of the LEAP (Learning Early About Peanut allergy) study, age-appropriate peanut-containing foods can be introduced to the diet of these infants as early as 4 to 6 months of age (with the caveat that peanut-specific IgE measurement, skin prick test, or both be strongly considered before introducing peanut to determine if it should be introduced and, if so, the preferred method of introduction).[23] LEAP, a randomised trial that investigated strategies for preventing peanut allergy in infants with severe atopic dermatitis or egg allergy (i.e., infants at high risk for developing peanut allergy), found that 1.9% of those who had peanut introduced in the first 4 to 11 months of life developed peanut allergy, compared with 13.7% of those who avoided peanut during the first 60 months of life.[32] A 12-month follow-up study (LEAP-ON) found the benefits of early peanut consumption to be long-lasting.[33]
In the EAT (Enquiring about Tolerance) study, the introduction of peanut and egg into the diet of exclusively breastfed infants from the general population (i.e., not selected based on risk of developing food allergy) between 3 and 6 months of age was shown to be protective against the development of peanut and egg allergy in those who adhered to the diet.[34] The early introduction of cows' milk, sesame, whitefish, or wheat was not protective. Adherence to each of the six allergenic food-containing diets proved difficult in the study.[34]
UK guidance recommends that infants should be exclusively breastfed up to 6 months of age, after which complementary foods (including peanut and egg) can be introduced, alongside continued breastfeeding, in an age-appropriate form, and when convenient for infant and family.[35]
Secondary prevention
There is evidence that breastfeeding for at least 4 months, compared with feeding formula made with intact cows' milk protein, prevents or delays the occurrence of atopic dermatitis, cows' milk allergy, and wheezing in early childhood. However, there are no apparent advantages to exclusive breastfeeding beyond 3 to 4 months for prevention of atopic disease.[26]
In studies of infants at high risk of atopy (and who were not exclusively breastfed for 4 to 6 months), there is a lack of evidence that the onset of atopic disease may be prevented by the use of hydrolysed formulas compared with intact cows' milk formula.[26][31][105]
World Allergy Organization (WAO) guidelines make no recommendation regarding the use of probiotic therapy for food allergy prevention, noting that there are very few studies in this clinical setting.[106] WAO guidelines suggest that prebiotics may be used in non-exclusively breastfed infants for food allergy prevention, but not in exclusively breastfed infants.[107] However, these recommendations are based on limited evidence. European guidelines have concluded that there is no evidence to support the use of prebiotics or probiotics for food allergy prevention.[31]
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