"It is a known fact that microbes on farms protect children from asthma and allergies. But even non-microbial molecules can have a protective effect. Immunologists have shown that a sialic acid found in farm animals is effective against inflammation of lung tissue. This study opens up a wide variety of perspectives for the prevention of allergies."

https://www.sciencedaily.com/releases/2017/07/170706072101.htm