Animal sialic acid helps our immune system to keep itself in hand.
Allergy, as is known, arises due to too strong an immune response to completely harmless substances; for example, the immune system suddenly perceives some food proteins as a sign of a dangerous infection and triggers a strong inflammation.
Sometimes immunity comes to the point that even the cells and molecules of the organism itself are considered outsiders – and then the autoimmune reaction begins. In general, autoimmune disorders and allergies are similar in that both there and there the cause of the problem is excessively vigilant immunity, unnecessarily so that everything can end in death.
One of the most famous examples here is asthma. Allergen, which can be ordinary dust, or plant pollen, or particles of animal hair, causes inflammation and spasm of the pulmonary bronchi. In recent years, the number of people with asthma and various allergies in general has been steadily increasing, and this is especially evident in children.
However, another thing is known: children who grow up on farms are much less likely to suffer from allergies and asthma than those who live in cities. Moreover, even those children who live in villages, but not on farms, are more likely to suffer from immune-allergic problems than their peers from farms.
By and large, all this is not new: doctors and biologists have long been discussing the so-called theory of excessive hygiene, the essence of which is that in order for the immune system to work normally, a person needs to spend some time in not very hygienic conditions. That is, the point is not that it is dirtier in a city than in a city, but vice versa – city dwellers are too careful of cleanliness, so our immunity from childhood sees a too limited set of bacteria, and therefore is not able to distinguish between harmless and frankly pathogenic. Roughly speaking, in order to work normally, the immune system must literally gain experience, and this concerns not only bacteria, but also a wide variety of substances.
In an article in the Journal of Allergy and Clinical Immunology, researchers at the University of Zurich write that children from farms suffer from asthma less often due to contact with animals that live on the same farms. And the reason here is not only in microbes, but also in a special substance – N-glycolylneuraminic acid from the group of sialic acids. Bacteria do not have it, but people have lost the ability to synthesize it themselves, but then we can use what animals have. Our body builds N-glycolyl neuraminic acid into other molecules, however, since we cannot do it ourselves, the immune system is able to react to it as something alien.
When the immune system encounters something foreign, it synthesizes the corresponding antibodies that bind to an unfamiliar molecule, and the resulting complex is “examined” by other immune cells. The authors compared the level of antibodies against N-glycolylneuraminic acid in thousands of children aged 5 to 14 years, and it turned out that those who grew up on the farm had higher levels of such antibodies, and they had asthma less often than others. Similar results were obtained in experiments on mice: animals that were threatened with asthma were fed food with the addition of N-glycolyl neuraminic acid, and as a result, the lungs of mice felt much better.
The paradox was that neither the children nor the mice from this acid did not decrease the level of immunoglobulins, which are usually associated with allergic reactions. She acted differently – because of N-glycolylneuraminic acid, the activity of regulatory T-lymphocytes increased, whose task is to control the strength of the immune response. It is T-regulatory lymphocytes that ensure that the immune system responds to the case and to the extent necessary; if necessary, T-regulatory lymphocytes, for example, reduce inflammation.
In other words, N-glycolyl neuraminic acid helps to avoid asthma, acting on the immune “counterweight” inflammation. As we said, we can get it from animals – for example, from fresh milk, or simply periodically contacting with a cow.
In general, from mammals it is not found in platypuses, ferrets, American monkeys, many breeds of dogs are also deprived of it. But N-glycolyl neuraminic acid is in cats, which, it turns out, by their mere presence can be beneficial – in any case, stroking a cat is better than nail biting.