The properties of donkey milk appear to make it suitable for infants who are allergic to cow’s milk, according to Italian scientists.
It had a set of neutraceutical properties that also made it suitable for those recovering from illness and the elderly, the researchers said.
Silvia Vincenzetti and his University of Camerino colleagues, in a review published in the journal Beverages, said donkey milk could be considered a good and safer alternative, compared to other types of milk, for infants affected by cow’s milk protein allergy, when breastfeeding was not possible.
“Interestingly, donkey milk has low allergenicity, mainly due to the low total casein amount, and the content of some whey proteins that act as bioactive peptides,” they said in their paper, which cited 79 scientific studies.
The amount of lysozyme, an antibacterial agent, is similar to human milk, they noted.
Donkey’s milk contained several proteins with anti-microbial and anti-viral functions. For example, its levels of α-lactalbumin, which shows antiviral, antitumor, and anti-stress properties, was very close to that of human milk.
Donkey milk could therefore be considered to have nutraceutical properties that made it suitable not only for growing infants, but for all ages, especially for convalescents and for the elderly.
Milk, they said, was a natural beverage which met the nutritional needs of infants. Fats varied widely between different species both in their concentration and chemical composition, from less than 1% in donkey milk to more than 50% in aquatic mammals.
Regarding carbohydrate content, lactose concentrations varied from 0.7% to about 7% among the different mammal species.
Milk protein content ranged from 1% to 24% by milk weight depending on the mammalian species.
There are two major categories of milk proteins that are defined by their chemical composition and physical properties: caseins and whey proteins. The caseins, which account for about the 80% of milk proteins in ruminants, are responsible for the transport of calcium and phosphate, and for the formation of a clot in the stomach for efficient digestion.
The ratio of casein/whey proteins differs among species — in human milk, the ratio is about 40/60 and in mare’s milk it is around 50/50, while in cow, goat, sheep, and buffalo’s milk it is about 80/20. These differences reflect the nutritional and physiological requirements of the newborn of these species
Vincenzetti and his colleagues said the prevalence of adverse reactions to food is higher in children (6–8% in the early years of life) than in adults (2.4%)
Studies in various countries showed that about 2.5% of children in the first year of life had allergic reactions to cow’s milk, which made it the main cause of allergies in children.
Cow’s Milk Protein Allergy (CMPA) centers around an abnormal immunological reaction to cow milk proteins.
The causes of allergies to cow’s milk were many, they said, some rooted in its different levels and ratios of important constituents when compared to human breast milk.
Once CMPA was established, the therapy, as in all food allergies, consists of excluding cow’s milk and products containing its allergenic proteins.
“When breast milk is insufficient or unavailable, it is indispensable to choose an alternative milk formula.
In the case of infants affected by CMPA, the elimination of the allergen usually led to the disappearance of the symptoms. However, some patients may also show the allergic reaction if a substitute for cow’s milk is used, thus indicating multiple food allergies.
Multiple food allergies were difficult to treat, they said.
Donkey milk, with its low allergenic properties, has been appreciated for its benefits and versatility as a food for newborns since ancient times. “But only recently, scientific research has proven its importance in human nutrition.”
This was especially so for the elderly, as well as infants affected by CMPA.
“When it is not possible to breastfeed, and especially in the case of CMPA, it is necessary to find a safe and valid alternative milk that meets the needs of the infant.
“The various kinds of alternative milk are certainly valid and ensure good child growth, however, sometimes they are characterized by an unpleasant taste and a high cost.”
Further, in the case of multiple food allergies, they may themselves cause unwanted allergic reactions.
“Donkey milk is considered a milk similar to human milk, especially regarding its protein composition. Therefore, as well as breast milk, it is able to respond to all the food needs of the newborn. Donkey milk is also an important food in the geriatric field and in cases of calcium deficiency.
“Some studies have shown that donkey milk … may be the treatment of choice in children with food allergies in early life, who often do not respond to other therapies.
“Unlike other breast milk substitutes, characterized by nutritional deficiencies and induction of allergic reactions, this natural food proves to be able to nourish infants at low risk of allergenicity and also allows for the development of a normal and complete immune system.
“With this in mind, we can consider donkey milk not simply as a food, but as a nutraceutical. We consider it to be used not only in early childhood nutrition, but also as a supplement in the diet of adults and the elderly,” they found.
The review team traversed the qualities of donkey’s milk when compared to human breast milk, noting its many similarities and some differences. It was notable for its clinical tolerability, palatability, and nutritional adequacy for children affected by a cow’s milk allergy.
It provided antibacterial substances, digestive activity molecules, growth factors, and hormones.
Its hypoallergenic properties could be explained by the results of clinical studies showing the structural similarities between human and donkey milk proteins.
However, its low lipid content, and consequently its low energy value, also needed to be considered, which could limit the use of this kind of milk for feeding children affected by an allergy to cow’s milk.
“For this purpose, more clinical studies designed to evaluate the nutritional efficiency of donkey milk in the first years of life should be encouraged,” they said, noting that there were too few existing reported case studies.
The review team comprised Vincenzetti, Stefania Pucciarelli and Valeria Polzonetti, from the School of Bioscience and Veterinary Medicine at the University of Camerino, and Paolo Polidori, from the university’s pharmacy school.
Role of Proteins and of Some Bioactive Peptides on the Nutritional Quality of Donkey Milk and Their Impact on Human Health
Silvia Vincenzetti, Stefania Pucciarelli, Valeria Polzonetti and Paolo Polidori.
Beverages 2017, 3(3), 34; doi:10.3390/beverages3030034