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COUNTRY LIFE IN BC • JANUARY 2019
According to new research by scientists at the American College of Allergy, Asthma and Immunology, cow’s milk is the most common food allergy in children under five years of age. More than
by MARGARET EVANS
2% of all US children under five and 53% of infants under one year have a cow’s milk allergy. The good news is that most children outgrow
this allergy as they advance into their teen and adult years, and are able to enjoy this essential food product. In fact, the rate of milk allergy drops from 53% to 41% for children one to two years old, 34% for those aged three to five and 15% for youth aged 11 to 17. The one-year study surveyed 53,000 parents from October 2015 to September 2016. An important difference exists between a milk
allergy and intolerance. According to the Mayo Clinic, a milk allergy is when the immune system identifies certain milk proteins as harmful, triggering the production of immunoglobulin (IgE) antibodies to neutralize the protein. Healthy Families BC says on its website that when milk products are eaten, the antibodies cause an inflammatory response in the skin, respiratory tract, gastrointestinal system, or the cardiovascular system. A cow’s milk allergy carries the risk of other allergic diseases such as atopic dermatitis or allergic asthma. By contrast, lactose intolerance is caused by low
levels of the enzyme lactase responsible for breaking down lactose, a sugar found in milk. Symptoms of this intolerance are limited to the digestive tract. Lactose-free milk has lactase added
Increasing green fodder could decrease allergies Research
Milk allergies affect two to three percent of infants but most outgrow it by three years
to neutralize the lactose and eliminate digestive trauma.
But there might be a solution to milk allergy, too, and it could all come down to the abundance of the amount of green fodder that cows eat. Like North American children, about 3% to 5% of
European children suffer milk allergies. The onset of symptoms occurs most frequently during the first year of life, when up to 7.5% of infants become sick. However, the majority of them outgrow the milk allergy by adulthood. In early 2018, research conducted by the interuniversity Messerli Research Institute of Vetmeduni Vienna, Meduni Vienna and the University of Vienna found that an allergic reaction to milk could be prevented by two components of cow’s milk interacting together. The key, the scientists write, lies in the milk
protein beta-lactoglobulin (Bos d 5) which represents up to half the whey fractions and 12% of whole cow’s milk protein, making it the allergen eliciting most IgE-initiated reactions in allergic people. Bos d 5 is part of a family of proteins known as the lipocalins. If infants become allergic to cow’s milk, their bodies produce specialized immune cells called Th2 lymphocytes. They fight milk proteins as part of the immune system, including Bos d 5. “This special protein family [lipocalins] is
characterized by molecular ‘pockets’ that can take in small molecules like retinoic acid, which is a metabolite of vitamin A,” says Karin Hufnagl with the University of Veterinary Medicine, Vienna, and lead author of the report published in Scientific Reports. “Our study showed that an ‘empty’ milk protein
supports the activation of Th2 lymphocytes and so initiates an allergic chain reaction,” says Hufnagl.
However, if it pockets the retinoic acid, then the immune cells react moderately, without an allergic immune reaction. “An adequate loading of the milk protein could
thus prevent small children or even adults from becoming sensitized and expressing a milk allergy,” summarizes study leader Erika Jensen-Jarolim. The key to this equation is an adequate supply of vitamin A in the cows’ feed. “A sufficient supply of vitamin A to cows could counteract [the] effect in which a harmless food protein is converted into a milk allergen,” says Hufnagl. However, it is uncertain whether the same
positive effect of natural vitamin A demonstrated in the study is also achieved through dietary supplements. “Artificial supplementation of a diet with vitamins
may not achieve the same effect as natural agents and will likely result in inadequate loading of the milk allergen,” says Hufnagl. “It is therefore necessary to supply vitamin A to an appropriate extent during the keeping or feeding of the animals. This can be achieved, for example, by increasing the supply of green fodder.” Hufnagl says corresponding follow-up studies must still be carried out. A child’s reaction to milk, whether it be an intolerance or an allergy, is always something to be taken seriously and requires testing and confirmation by an allergist. A food allergy of any kind can have a huge effect on a family’s budget, lifestyle and even safety. Families need to have a full understanding of the far-reaching implications that an allergy to milk can have in terms of the wide- ranging food items made with milk and milk products.
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