Exploring Allergies to Milk and Milk Alternatives
Posted by Leanne Kodsman on
A (cow's) milk allergy is one of the most common allergies in the United States, but for individuals with this allergy, it can be tricky to know what type of alternative would make for an acceptable, non-allergenic substitute. A new study, recently published in the Journal of Dairy Research, investigates the general allergenicity and antigenicity of different mammalian milks and plant-based milk substitutes in an effort to identify which option(s) would likely be the safest alternative for otherwise healthy individuals who are allergic to proteins found in cow's milk.
A cow's milk allergy is not uncommon. In fact, it is ranked among the "Big 8" - a set of foods that account for more than 90% of food-related allergic reactions in the United States. The other top allergenic foods, if you're curious, include peanuts, tree nuts, eggs, wheat, soy, fish, and shellfish. All of these foods contain unique proteins that can trigger a strong, IgE-mediated allergenic response by the body's immune system in allergic individuals. Between 2% and 5% of children are estimated to be affected by an allergy to cow's milk. While many children outgrow this allergy, for some individuals it can persist into older childhood, adolescence, and even adulthood.
A new report, "Immune reactivity against a variety of mammalian milks and plant-based milk substitutes," was recently published in the Journal of Dairy Research and looks to identify the least-reactive milks among a population of 500 unique, healthy individuals. The milks analyzed include variations of cow, goat, sheep, camel, and human varieties as well as soy, almond, and coconut plant-based milk substitutes.
500 different single donor human serum samples were obtained from Innovative Research for this study.
Lactose Intolerance vs. Cow's Milk Protein Allergy
"Lactose intolerance" and "milk allergy" are often confused, as they are commonly used colloquially in much the same way. An allergy to milk, however, is quite different from lactose intolerance even though the two can sometimes result in similar symptoms.
Lactose is a sugar present in cow's milk, and lactose intolerance happens when an individual's body cannot digest this sugar appropriately. This typically occurs due to a lost or reduced ability to produce the enzyme lactase, which is the primary enzyme responsible for breaking down lactose. Unlike an allergy, this intolerance is not an immune response.
A milk allergy, on the other hand, occurs when the immune system responds to various components that are found in milk as though they were harmful. There are two main types of allergies to cow's milk: the first is an IgE-mediated response, where the immune system sees the proteins in milk as pathogens and responds by releasing chemicals like histamine; the second is a non-IgE-mediated, or delayed, response.
With an IgE-mediated reaction, symptoms frequently begin within minutes of consuming milk. These symptoms look similar to other common allergic reactions and can range from a stuffy nose to anaphylaxis. With a non-IgE-mediated reaction, however, symptoms are more likely to mirror those of lactose intolerance and present with cutaneous (hives, rashes, itching...) and/or gastrointestinal (nausea, abdominal pain...) symptoms.
Allergenicity and Antigenicity of Mammalian Milks
To determine the general rate of allergic response to the different kinds of milk being tested, the research team used a selection of 500 unique single donor human serum samples from Innovative Research. These donors were from a cross-spectrum population from age 18 to age 65. The team tested these samples for immunoglobulin response, looking at IgA, IgE, and IgG as measured by enzyme-linked immunosorbent assay (ELISA).
The team found human milk to be the least reactive, followed by camel, sheep, goat, and cow (in that order). For individuals identified to have an allergenic response to cow's milk, the researchers measured the response to several different forms, including organic, non-organic, A1, and A2. They did not see a difference in reactivity among the different types of cow's milk - if an individual was allergic to one form, they were observed to be reactive to all forms. This cross-reactivity was not unexpected, though, as the varied types of cow's milk still contain many of the same major proteins.
Cow, goat, and sheep milk have many similarities when it comes to their respective caseins and alpha-lactalbumin. The researchers note that for 92% of individuals with an allergenic response to cow's milk, there is an allergenic response to goat and sheep milks, as well. Camel milk has a different casein and smaller immunoglobulins as compared to cow, goat, and sheep milks. This difference seems to make camel milk less allergenic in general. An individual with an allergenic response to cow's milk has a 50% chance of reacting to both camel and human milks, as well.
Allergenicity and Antigenicity of Plant-Based Milk Substitutes
Someone who is allergic to one type of mammalian milk is likely to react to other types of mammalian milks (with the possible exception of camel and/or human milks). Many individuals with an allergy to cow's milk will look to plant-based milk substitutes as an alternative. But are these any less likely to result in an allergenic response?
To find out, the researchers looked at reactivity to soy, almond, and coconut milk substitutes to determine the general allergenicity and antigenicity of these common alternatives.
In general, the overall allergenicity of the plant-based milks was lower than that of the mammalian milks. However, for some reactive individuals, there is still a very strong allergenic response. While coconut milk looks to be the least allergenic/antigenic, in some individuals, the reaction to coconut milk could be as strong as that to almond, soy, sheep, goat, or cow's milk.
There were some individuals who demonstrated reactivity to both mammalian milks as well as plant-based milks, but this immune response is not because of any similarity in antigens. Instead, this is due to the allergenicity of the plant-based products overall.
How to Avoid Allergenic Response
From this research, it's not possible to say that one type of milk is best, or that for an individual with an allergy to cow's milk, plant-based alternative milks are a safe alternative when it comes to avoiding allergic reaction. While there are some favorable results seen with the plant-based milk substitutes (mainly a lower instance of reactivity across the entire population studied), it seems that there still exists a percentage of individuals who demonstrate a strong allergenic response to these milks.
In general, blood tests for IgA, IgE, and IgG antibodies is the most accurate way to determine which milks should be avoided.
Further Reading & References:
Immune reactivity against a variety of mammalian milks and plant-based milk substitutes. Aristo Vojdani, Chris Turnpaugh, and Elroy Vojdani. Journal of Dairy Research, August 2018
Innovative Research was established in 1998 after the realization that dependable, high-quality, and affordable research materials were hard to come by. Starting with core products like human plasma and serum, Innovative Research has grown to be a trusted supplier of all lab reagents, including human biologicals and ELISA kits. Today, we manufacture and supply over 3,000 high-quality human and animal biologicals including plasma, serum, tissues, and proteins.