Cow’s Milk Antigens Content in Human Milk: A Scoping Review

Abstract

The functionality of breast milk in terms of immunity is well-known. Despite this, a significant proportion of breastfed infants exhibit sensitization to different potentially allergenic proteins and clinical reactivity (including anaphylaxis) early in life and before the introduction of complementary feeding for the first time. The potential induction of early oral tolerance to overcome early allergic sensitization through exposure to allergens in breast milk also remains controversial and not yet well-established. The objective of this scoping review is to provide a critical appraisal of knowledge about the content of cow’s milk antigens in human milk. The amount of dietary derived milk antigens found in human milk and the analytical methodologies used to detect and quantify these antigens, the allergic status of the mother, the stage of lactation, the time of sampling (before or after ingestion of food), and the impact of human milk allergen on the infant were the outcomes that were assessed. Allergy risk was explored in all reviewed studies and could help to better elucidate its role in the context of allergic disease development. According to the included literature, we can conclude that there are mainly fragments derived from bovine proteins in human milk, and the presence of potentially allergenic molecules is greater in the milk of mothers with an allergic tendency. A clear relationship between maternal diet and allergen content in breast milk could not be firmly concluded though. Also, infants receiving milk from human milk banks, where donor milk is pasteurized for preservation, may be subject to greater risk of allergy development, especially for β-lactoglobulin.

Non-IgE mediated food allergies in breastfed children: A clinical challenge

“…This publication found the presence of β-lactoglobulin, a bovine milk protein, in human breastmilk at similar levels previously published by Høst and Halken (range 0.9 – 150 µg/L) [ 9 , 10 ]. Interestingly, they found that in some breastmilk samples, β-lactoglobulin was detected up to 7 – 10 days after stopping the consumption of cow’s milk [ 9 ]. This review found a significant correlation between high levels of β-lactogobulin in breast milk to clinical manifestations such as diarrhea, vomiting, colic, or eczema, which are all typical non-IgE mediated symptoms [ 11 , 12 ].…”

“…At the heart of the debate of non-IgE mediated allergy in breastfed infants, is the question to whether maternally consumed food allergens can lead to symptoms. A recent scoping review found 27 studies assessing bovine milk protein in breastmilk that included data on the type of sampling method, the sampling time, the lactation stage, maternal allergy status, and, most importantly, the impact on the infant [ 9 ]. This publication found the presence of β-lactoglobulin, a bovine milk protein, in human breastmilk at similar levels previously published by Høst and Halken (range 0.9 – 150 µg/L) [ 9 , 10 ].…”

“…A recent scoping review found 27 studies assessing bovine milk protein in breastmilk that included data on the type of sampling method, the sampling time, the lactation stage, maternal allergy status, and, most importantly, the impact on the infant [ 9 ]. This publication found the presence of β-lactoglobulin, a bovine milk protein, in human breastmilk at similar levels previously published by Høst and Halken (range 0.9 – 150 µg/L) [ 9 , 10 ]. Interestingly, they found that in some breastmilk samples, β-lactoglobulin was detected up to 7 – 10 days after stopping the consumption of cow’s milk [ 9 ].…”

“…This was argued by Munblit et al [ 14 ] in 2020, who, based on a theoretical calculation, suggested that only 1 in 600 breastmilk samples, would contain sufficient β-lactoglobulin to elicit a reaction in 1% of the most sensitive patients with CMA. Indeed, in the publication by Franco et al [ 9 ] this point was also considered with only a few samples from three studies reaching a level of β-lactoglobulin ≥ eliciting dose for 1% (ED01) of allergic individuals, and in no case did the samples contain beta-lactoglobulin in concentrations ≥ ED05 [ 12 , 15 , 16 ]. The probability therefore, according to this publication, of having enough β-lactoglobulin in breastmilk to trigger an allergic reaction has been estimated at 1 : 2,893 [ 9 ].…”

“…Indeed, in the publication by Franco et al [ 9 ] this point was also considered with only a few samples from three studies reaching a level of β-lactoglobulin ≥ eliciting dose for 1% (ED01) of allergic individuals, and in no case did the samples contain beta-lactoglobulin in concentrations ≥ ED05 [ 12 , 15 , 16 ]. The probability therefore, according to this publication, of having enough β-lactoglobulin in breastmilk to trigger an allergic reaction has been estimated at 1 : 2,893 [ 9 ].…”