Cow milk proteins likely trigger of broader immune response with MS

A significantly higher immune response against proteins found in cow milk is evident in people with multiple sclerosis (MS), likely because of similarities between milk proteins and proteins in the human central nervous system (CNS, the brain and spinal cord), a study reported.

No such differences were seen between patients and healthy adults with almond and other plant-based milks or with sheep milk, but the researchers cautioned against assuming that plant-based milk alternatives are “automatically a better choice.”

Rather, they “suggest screening of blood from MS patients for antibodies against different types of milk and milk antigens [proteins that trigger an immune response] in order to establish a personalized diet regimen.”

The study, “The prevalence of IgG antibodies against milk and milk antigens in patients with multiple sclerosis,”  was published in the journal Frontiers in Immunology.

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High antibody levels against cow milk proteins seen in patients’ blood

MS is a complex neurodegenerative disease thought to arise from a combination of genetic and environmental factors.

Diet has been suggested as a potential factor that modulates the immune response in people with MS. In particular, cow milk and dairy products may enhance the inflammatory responses seen in the disease.

Researchers believe this is due, at least in part, to similarities between proteins in cow’s milk and those in a person’s central nervous system. When the immune system reacts against milk proteins, some antibodies also react to CNS proteins and damage nerve cells.

Most studies have focused on cow’s milk, however, so whether other animal- and plant-based milks might trigger similar inflammatory responses is not known.

Researchers in Germany analyzed blood samples from 35 MS patients and 20 healthy adults as controls. Women made up the majority of both groups, whose mean age was in the late 30s.

Specifically, the scientists measured blood levels of antibodies against nine different sources of mammalian and plant-based milk.

Animal milks tested were cow, goat, sheep, and A2 milk (a variety of cows’ milk that mostly lacks a form of the beta-casein protein called A1). Plant-based sources were almond, coconut, cashew, hazelnut, and oat milk.

MS patients had significantly higher levels of antibodies against cow milk, followed by goat milk, when compared with controls. Healthy adults had a significantly higher immune response against A2 milk than did patients.

No differences between these groups were seen regarding sheep milk or the various plant-based milks.

High levels of antibodies to beta-casein, an abundant milk protein

Further analyses focused on determining which proteins caused the exacerbated immune reaction to cow milk. Results found high levels of antibodies against beta-casein, one of the most abundant proteins in cow’s milk, in people with MS.

A statistical analysis also suggested a potential correlation between high antibody levels against beta-casein and more severe disability, as measured with the Expanded Disability Status Scale (EDSS).

While present at low levels in blood, anti-alpha-lactalbumin antibodies drove the greatest reactivity against cow milk. However, antibodies targeting beta-lactalbumin, another cow milk protein, showed the greatest reactivity against brain tissue samples, the researchers reported.

Based on these findings, they proposed that the immune response to cow milk proteins is the result of a cross-reactivity to proteins found in the brain and spinal cord.

“We hypothesize that consumption of animal-based milk antigens that share sequence or structural homology [similarities] with human tissue-specific proteins can result in mimicry-induced misfires of the immune system in susceptible individuals,” the scientists concluded.

Additional studies into this area are needed, including into the potential impact of disease-modifying MS therapies on patients’ immune response to milk antigens, they added.