Nutrition and Health | Milk Allergy

Abstract

Allergy means an altered or abnormal immunological reaction. The allergen may reach the tissues by direct contact with the skin or mucous membranes or through the bloodstream after absorption. Allergy to milk proteins is one of the main food allergies and affects mostly but not exclusively infants, while it may also persist through adulthood and can be very severe. Population-based studies on the incidence of milk allergy (MA) have reported that the incidence varies widely from 0.3 to 7.5%. Symptoms of MA can appear immediately or start several hours or even days after the intake of moderate to large amounts of milk or its products or infant formula. A wide spectrum of clinical manifestations has been recorded with MA. Diagnosis of MA can be achieved by skin or blood tests. Milk contains more than 20 proteins (allergens) that can cause allergic reactions. The most common milk allergens are caseins and β-lactoglobulin (β-Lg). Although β-Lg is a major whey protein fraction in the milk of dairy animals, human and camel milks are free of β-Lg. Several trials have been made to reduce the allergenicity of cow milk proteins by heat or partial enzymatic treatment. Allergies to milk proteins of non-bovine mammals have also been documented due to cross-reactivity between cow milk proteins and their counterpart in other species. Genetic polymorphisms of milk proteins play an important role in eliciting different degrees of allergic reactions. For example, goat milk lacking α-s1-casein, which is the main casein in cow milk, is less allergenic than goat milk with α-s2-casein, which is more typical for many goat breeds. Several studies have reported that goat or even soy milk can be used as alternatives in cases of cow MA and they can be considered hypoallergenic. However, therapeutic benefits vary with the degree of severity of the allergy and may be only around 60% of all cases, since other studies revealed allergenicity to occur also for any of those other milks. Recently, an absence of immunological similarity between camel and cow milk proteins was reported. Therefore, camel milk may be suggested as a new protein source for the nutrition of children allergic to cow milk and can be used as such or in a modified form.