Cow’s Milk Protein Elimination Diet in Breastfeeding Mothers When Cow’s Milk Protein Allergy (CMPA) Is Suspected in the Breastfed Baby: What Do Studies Say?
- Elise Armoiry My Baby Moon
- Dec 2
- 7 min read
Very frequently during consultations, mothers tell me they are following a cow’s-milk-protein-(CMP) elimination diet. Because the baby spits up, you can hear the milk coming back up, the baby “chews,” only sleeps in arms, or has green stools, or cries a lot. Sometimes this diet is started without medical advice and for an extended duration.These very restrictive diets can impact mothers’ mental health, especially after the dietary constraints of pregnancy (during which a gestational diabetes diet may also have been implemented), and lead to early weaning.
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European recommendations were issued in 2024 (1), and a recent study published in July 2024 addresses the topic of CMP elimination diets in breastfeeding mothers (2).
Reminders on the Allergic Reaction
An allergic reaction corresponds to an inappropriate reaction of the immune system to a triggering element (allergen protein) considered “foreign,” though it should normally be tolerated.The immune reaction triggered can be of 3 types:
IgE-mediated reaction: in this case, the allergic reaction is rapid (immediate or within hours after ingestion) with the appearance of symptoms (e.g., hives, eczema, vomiting, diarrhea), sometimes very severe (anaphylaxis: respiratory distress and laryngeal edema, tachycardia, collapse) and requiring an epinephrine injection (3).The likelihood of an IgE-mediated reaction in a breastfed child is estimated at less than 0.1%.
Non-IgE-mediated reaction: in this case, the reaction does not appear immediately but between 6 and 72 hours after ingestion, and the signs are generally digestive: irritability, diarrhea, vomiting, bloody stools, atopic dermatitis (and in rare extreme cases severe eczema and enteropathy) (1,2).
Mixed: IgE-mediated and non-IgE-mediated
In breastfed babies, they may react to a protein found in human milk; the most common allergen is cow’s milk protein (CMP). Other allergens may be involved: soy, eggs, shellfish, peanuts, fish, wheat (4) (these diets are never spontaneously undertaken by mothers even though the prevalence of these allergies is not zero).
Transfer of Cow’s Milk Proteins into Human Milk (2)
The concentrations of allergens (milk beta-lactoglobulin, milk casein, egg ovalbumin and ovomucoid, peanut) in human milk are very low, so their possible allergic impact, or role in preventing atopy, is debated.Before reaching the milk, these proteins have been digested in the maternal intestine, then reach the mammary gland where they create peptides the baby’s body will tolerate.The concentration of beta-lactoglobulin in breast milk varies greatly between women for the same amount of milk ingested, certainly depending on their allergic status and intestinal absorption, and CMP can be found in breast milk up to 10 days after ingestion.There appears to be considerable inter- and intra-individual variability in allergen secretion into breast milk, and in some cases no allergen is found after ingestion.The concentrations found in breast milk are minimal, and one study indicates that in 99% of cases, these concentrations are not sufficient to trigger an allergic reaction. (1-2)
Incidence: It is estimated that 0.5% of breastfed babies are allergic to CMP versus 1% of non-breastfed babies (1).Because human milk contains far less CMP than infant formula, severe reactions are rare.
What Are the Risk Factors and Signs of CMPA in Children?
Risk factors
A family history of allergy (asthma, eczema, hay fever)
Environmental factors (pollution, antibiotic therapy, reflux medications such as PPIs) may also play a role (1).
Signs observed in CMPA (1,2,5-8,10)
Skin reactions: rash, eczema, hives, swelling around the lips or eyes
Rhinitis, otitis, chronic cough
Digestive problems: diarrhea, constipation, colic, pain, vomiting
Irritation, crying, “colic”: there is very often a diagnosis of “reflux” or “internal GERD”: see this article on Gastroesophageal Reflux and the latest HAS recommendations
Note: Green stools or mucus stools are not considered pathological in a baby who is otherwise doing well (1).
Particular Cases of Allergy
Food-protein-induced proctocolitis is mainly seen in breastfed infants: this is a case where blood is observed in stools. It is an inflammation of the colon in contact with food proteins and is not IgE-mediated. In moderate cases, European experts (1) do not recommend an elimination diet in the mother but observation.If a diet is undertaken, it should last 2–4 weeks before a reintroduction trial.In severe cases of prolonged blood in stools, an elimination diet in the mother is possible. The authors indicate that there is no study on cross-allergies with sheep and goat’s milk, but it seems logical to eliminate all animal milks.Bloody stools may also be linked with benign non-allergic infantile proctocolitis (12), and up to 20% of breastfed infants show spontaneous resolution of symptoms such as rectal bleeding without changing the mother’s diet.
Food-protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy, and cow’s milk is one of the main allergens. It presents rapidly (1–4 hours after ingestion) with significant vomiting associated with pallor, sometimes diarrhea and lethargy. This is very rare in breastfed infants.
Eosinophilic esophagitis is also related to CMPA: it manifests as reflux and dysphagia, and symptoms improve with CMP elimination (see our article on GERD).
European specialists (1) indicate that CMPA is frequently overdiagnosed.This overdiagnosis is likely supported by the marketing of infant-formula companies (recently denounced in 2023 by WHO and already in 2018 in the British Medical Journal). (9)
Another possible cause of the signs mentioned are functional digestive disorders, common (25%) in otherwise healthy infants, causing constipation, regurgitation, distress crying, and “colic.” These nonspecific symptoms can lead to an elimination diet, which may sometimes bring improvement (placebo effect, reduction of lactose, natural evolution) and induce false diagnoses (1). Most often, it is a conveniently simple explanation for a complex problem.
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In Clinical Practice as a Lactation Consultant
In addition to the previously mentioned signs described by parents, one may observe:
slow weight gain, or a baby who nurses very, very frequently
a baby diagnosed with gastroesophageal reflux because of intense crying and regurgitation
a baby restless at the breast, who latches and unlatches or clamps the nipple (reflex response due to digestive pain), refuses the breast, or starts crying mid-feed although still appearing hungry.
During the breastfeeding consultation, there are other possible causes for the signs mentioned in suspected allergy:
crying during or after feeding, loose stools, regurgitations may, for example, be seen in cases of oversupply
crying can have many causes, particularly the immaturity of the nervous system before 4 months, the newborn’s intense need for closeness, hunger and insufficient number of feeds (especially if the mother has been told that baby “must finish the breast to get the fatty milk” or “must space feeds 2 hours to digest”) (see this article on GERD)
Diagnosis and Management
Diagnosis:
A diagnosis should be made by a doctor. Self-diagnosis risks causing prolonged elimination diets with risks of nutritional deficiencies.
Management : Cow’s Milk Protein Elimination Diet
An elimination diet will be recommended to the breastfeeding mother by a nutrition professional, meaning a dietitian or a nutrition-focused physician, with observation of symptoms followed by reintroduction of the allergen after 2 to 4 weeks (1) to confirm the diagnosis. This is a dietary treatment, therefore any other professional suggesting elimination is acting outside their scope of practice.
Note: The authors of the article on elimination diets (2) indicate that foods labelled “may contain traces of” are very unlikely to trigger an allergic reaction.If the mother is doing mixed feeding, a special allergy-formula milk will be prescribed. These allergy-specific formulas are not recommended for allergy prevention when supplementing a breastfed baby: this is explained in this article.
In the case of a prolonged elimination diet, supplementation with calcium and vitamin D is recommended, and iodine and B12 supplementation should be considered (1,2).Again, this requires monitoring by a nutrition professional.Iodine needs increase during breastfeeding, and one of the sources of iodine is animal milk. In France, an intake of 200 micrograms per day of iodine is recommended for breastfeeding women. Iodine contributes to the formation of thyroid hormones (11). The main dietary sources of iodine are seaweed in highly variable amounts, iodized salt (not sufficient as the sole source), marine fish, shellfish, egg yolk, and dairy products depending on the animals’ diet. An iodine deficiency could also explain low appetite and slow weight gain in the baby.
Conclusion
Cow’s milk protein elimination diets in breastfeeding mothers are not harmless and can cause nutritional deficiencies in mother and child, as well as early weaning. They are restrictive, generate stress and reduce quality of life. They decrease maternal confidence in breastfeeding, with mothers sometimes feeling they are “poisoning their baby.”Before implementing an elimination diet in a breastfeeding mother, a medical diagnosis must be established, professional follow-up implemented, and reintroduction of CMP performed to confirm the diagnosis and avoid unnecessary prolonged elimination diets.A breastfeeding assessment by an IBCLC lactation consultant can help rule out other causes for nonspecific signs of CMPA.
Disclaimer
This article is intended to provide general information and does not replace medical advice. It is essential to consult a healthcare professional for any questions regarding your personal situation.For personalized breastfeeding support you can make an appointment.
Bibliographie
Vandenplas Y, Broekaert I, Domellöf M, Indrio F, Lapillonne A, Pienar C, Ribes-Koninckx C, Shamir R, Szajewska H, Thapar N, Thomassen RA, Verduci E, West C. An ESPGHAN Position Paper on the Diagnosis, Management, and Prevention of Cow's Milk Allergy. J Pediatr Gastroenterol Nutr. 2024 Feb;78(2):386-413. doi: 10.1097/MPG.0000000000003897. PMID: 38374567.
Gelsomino, M.; Liotti, L.; Barni, S.; Mori, F.; Giovannini, M.; Mastrorilli, C.; Pecoraro, L.; Saretta, F.; Castagnoli, R.; Arasi, S.; et al. Elimination Diets in Lactating Mothers of Infants with Food Allergy. Nutrients2024,16,2317. https:// doi.org/10.3390/nu16142317
Breastfeeding Network:Cows’ Milk Protein Allergy (CMPA) and Breastfeeding
NHS :What should I do if I think my baby is allergic or intolerant to cows' milk?
Carol Smyth. Why infant reflux matters.
BMJ. Overdiagnosis and industry influence: how cow’s milk protein allergy is extending the reach of infant formula manufacturers 2018
Protocole de l'Academy of Breastfeeding Medicine 24 . 2011. Allergic Proctocolitis in the Exclusively Breastfed Infant 10
CDC. Iodine. Consulté le 07/08/2024
Gelsomino M, Sinatti D, Miceli Sopo S. Non-allergic benign infantile proctocolitis: a neglected nosographic entity. BMJ Case Rep. 2021 Oct 19;14(10):e244918. doi: 10.1136/bcr-2021-244918. PMID: 34667039; PMCID: PM
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