Cow’s milk is the most common source of allergenic reaction to milk proteins as it is consumed the most. This study compared the milk allergy profiles of cow, goat, camel and donkey milk. The allergens, incidence of allergy, cross-reactivity, and if suitable for milk allergic patients were assessed. Studies substantiating the allergenic variability were reviewed in respect to milk protein allergenicity to produce an analysis of suitability for establishing hypoallergenic substitutes.
The main proteins involved in allergy, the contents of these proteins in these milks and their respective allergenic reactions, were given. Also the consideration of lactose intolerance in respect to milk allergy is to be noted, the reactions are different but are often confused with milk allergy.
Cow’s milk protein allergy (CMPA) is the most prevalent allergy seen in infants in fact, it is the most prevalent allergy in food, 2-6 % of the children are affected worldwide, this mainly due to the IgE-mediated reactions to the caseins and the whey proteins such as β-lactoglobulin (β-LG). The present study has undergone an updated milk allergy profile after researching recent literature (2023-2025) regarding protein cross-reactivity, protein homology, and clinical tolerance . These shows the cross-reactivity of cow’s and goat’s milk is very high (90-92%), low with camel (10-20% ) and very low with donkey milk (<10%) The main differences are the complete absence of the provocation of allergy with β-LG with both camel and donkey milk and the lower level of αs1-casein in goat’s milk. Also the overall looking at the protein sequence homology: cow-goat milk caseins ~ 88% , cow-camel milk ~60-70% and cow-donkey milk ~50%.
Summary of Milk Allergies:
Milk proteins that elicit an immune response (most often caseins—αs1, αs2, β and κ-casein and whey proteins—β-lactoglobulin, α-lactalbumin) cause milk allergies. This is an immune response to some of the proteins of milk and is different than lactase deficiency that causes lactose intolerance, which is simply an inability to digest milk. Cow’s milk allergy presently affects 2-6% of infants and 0.5-1% of adults with varying manifestations from mild (urticaria, eczema) to severe (anaphylaxis). Goat’s, camel’s and donkey milk are often substitutes for cow’s milk because of the differences in proteins, but sensitivity to these milks by patients varies in different individuals (potential cross reactions from milk vary), and tests are necessary to avoid potential risk of anaphylactic reaction.
COW’S MILK ALLERGY PROFILE:
Cow’s milk has a very high concentration of allergenic proteins, and therefore milk allergy is largely due to protein found in milk. The important allergens are:
• Caseins (80% of total protein constituent~26-28 g/L): αs1-casein (12-15 g/L), αs2-casein, β-casein and κ-casein. All are very immunogenic and difficult to digest with strong antibody formation and have more stable structures, so facilitate IgE-mediated hypersensitivity.
• Whey-proteins (20%~6-7 g/L): β-lactoglobulin (3-4 g/L) and α-lactalbumin (1-1.5 g/L). These are the major allergens, with β-lactoglobulin being the most potent as it is absent in human milk and this will make sensitization more assiduous.
Cow’s milk has a high level of casein and β-lactoglobulin and milk is not suitable for most allergic patients unless treated by desensitization therapy. Cow’s milk has the maximum incidence of allergy of all milks up-to 6% of infants affected, usually this will resolve by 5-6 years of age, but persists in some adults for many years. Symptoms include reactions of skins-atopic dermatitis, digestive tract reactions (vomiting, diarrhea), respiratory tract reactions (wheezy chaste) and rarely anaphylaxis.
Goat Milk Allergy Profile:
Goat milk has a similar protein profile to cow milk, with some clear differences impacting allergenicity.
• Caseins (~78% of protein, ~25-274g protein/L): Goat milk has lower αs1-casein (0.2-11% vs. 38% cow milk) which produces softer curds and may impact allergenicity for some, but the β-casein and κ-casein have similarities to cow milk which produces high cross reactivity.
• Whey Proteins (~22%, ~6 g/L): Contains β-lactoglobulin and α-lactalbumin which are slightly different in form to cow milk but retain the allergenic potential.
The prevalence of goat milk allergy is lower than cow milk but still not insignificant, since 40-90% of CMA patients cross-react due to similarities of the proteins found (such as 80-90% sequence similarities in caseins). It might be tolerable to those who have mild CMA due to lower levels of αs1-casein, but not hypoallergenic in its effect to most other patients. Symptoms resemble those of cow milk allergy, and include atopic dermatitis, gastrointestinal symptoms. Studies suggest camel milk is a poor substitute in most cases for CMA patients, with only a small subset tolerating it any better.
Camel Milk Allergy Profile:
Camel milk is currently being increasingly studied in regard to its hypothesized hypoallergenic effects, and is of particular value to those that reside in the arid regions of the earth where it is a staple part of the diet.
• Caseins (73% of protein, ~22-25g protein/L): These have a higher β-casein content (65-70%) and a lower αs1-casein content than cow milk, and differ in structure in such a way that IgE antibodies have less ability to attach to them. Cameline caseins show 60-70% homology with cow caseins which gives these proteins low cross reactivity.
• Whey Proteins (27% of protein ~7-8g protein/L): Important to note is the fact that camel milk is devoid of β-lactoglobulin, a major cow milk allergen. The α-lactalbumin in camel milk shows lesser homology with that of cow milk (50-60%), thus also reducing its ability to cause sensitization.
Camel milk shows great promise for CMA patients, with studies showing low cross reactivity (10-20% in CMA cohorts) and better tolerance rates, especially in children. Clinical trials show that 80-90% of CMA patients tolerate camel milk without symptoms occurring. This is probably due to the fact that camel milk has no β-lactoglobulin, and a different profile of casein protein. Allergic reactions to camel milk can occur in cases (i.e. mild urticaria) in highly sensitized individuals. The high pH of camel milk and the small size of the milk fat globules also add to its digestibility, and may be of particular aid to those that are lactose intolerant, although this is entirely separate from that of allergy.
Donkey Milk Allergy Profile:
Donkey milk is by far the closest in composition to that of human milk. Hence, it is the leading hypoallergenic milk:
• Caseins (~50%, ~5-9 g protein/L): It is very low in casein content (0.9-1.1 g protein/L), with little or no αs1-casein and with unique peptide structures, which minimize allergenicity. The homology with cow milks caseins is low (~50%).
• Whey proteins (~50%, ~5-9 g protein/L): The lysozyme (1.0 g protein/L) and lactoferrin content is abundant, showing no β-lactoglobulin and having a more immunogenic α-lactalbumin due to its less similarity in amino acid composition (lower homology than cow milk).
This results in a different profile than cow milk, which produces less immune responses to the donkey milk. Also it has the least amount of allergenic potential also, since trials have shown 90% – 95% tolerance of donkey milk in CMA patients including those with severe allergy symptoms. Since it has such low protein content in addition to the absence of β-lactoglobulin, it is a preferred product in new borns, infants, children and adult CMA patients.
The properties of milk being hypoallergenic are all definitely shown for various clinical uses in “desensitization” or as a base for making up formulas to be fed to infants. The symptoms exhibited, if any are little (i.e. slight rash), as clinically determined, and the objections to use under cross-reactivity with cow milk is virtually nil (<10%). If one is lactose intolerant (6.3% in donkey milk but also in camel milk) the high content of lactose itself (6.3%) in donkey milk may be problematic. But this is of no consequence to the hypoallergenic properties.
Considerations and Recommendations:
• Cow’s Milk: Avoid in all CMA patients since its highly allergenic. Desensitization or baked milk trials could possibly be done under medical supervision at an appropriate point in time.
• Goat Milk: Unfortunately goat milk continues to be an unsuitable alternative to mass use in CMA patients. Cross-reactivity between goat and cow milks make it a poor choice in most cases. However there are those with milder allergies who do well on goat milk products. Tolerance must be determined clinically.
• Donkey’s Milk: Donkey milk can certainly be a milk of first choice in clinical use in severe CMA cases especially babies or those with multiple allergies. Whereas due to immature commonness in treatment, its price and unavailability would preclude its wide spread use, it would certainly suffice in clinical institutional usage.
• Camel’s Milk: Certainly an excellent hypoallergenic milk and may be very good alternative in treatment of children with it’s hypoallergenic properties. However, the problem is in its availability. It is generally not common other than in hot countries. It is also expensive. Suitable for many CMA patients but requires individual testing .
Some Additional Points:
Lactose-intolerance is a data independent of milk allergy, except through the process of intolerance and malabsorption intolerant being the malabsorption, and preferably due to lactose. Donkey milk has this rate (6.3% lactose content) being the greatest, with cow and goat respectively 4.7%, camel 4.3-4.46% lactose). Camel and donkey milks may well be better tolerated by those lactose-intolerant children due to smaller fat globules which are more easily digested than in cow’s milk, however this has nothing to do with the hypoallergenic properties of the milk, which are in no way impaired. In terms of use all milks, especially at first, should be prescribed by an allergist who knows how better to treat certain conditions when different alternatives are approached. There are great individual variables in the use of various products for milks. Clinical tests with either skin prick tests or oral tests for tolerance show clear results.
Conclusion:
Cow’s milk has the greatest allergy potential, due mainly to the caseins and abundant amounts of β-lactoglobulin. Goat milk, while less allergenic for some patients still continues to show cross-reactivity. Camel’s and donkey’s milks are excellent hypoallergenic milks, the donkey’s being the purest to human’s and being the most tolerable of them, the camel next in order due to the absence of β-lactoglobulin.
They are therefore essential in the dietary needs for treatment of CMA patients’ diets, particularly those susceptible and sensitive to allergic manifestations and consequently they should be remembered that milks must be prescribed carefully due to the several variable responses made by individuals, preferences have to be made to the use of these milks on the advice of doctor and allergist, since there is still much in doubt in the results achievable and it is not always clear in its instances due to lack of commonness of use against the great bulk of test observations.