Why does this happen, and can it really “boost immunity,” as some claim? We checked what science says.

Childlike curiosity and a lack of inhibitions

Eating nasal discharge is a phenomenon most commonly observed in children. Little ones explore the world with all their senses, including taste, and have not yet developed social norms. In this way, they test what is and is not allowed. In adults, the habit may persist as a reflex—similar to nail-biting or picking at the skin around the nails.

What does nasal discharge contain?

Boogers are not just “dirt.” Nasal discharge consists mainly of mucus (mucopolysaccharides), some proteins, enzymes (e.g. lysozyme, which fights bacteria), immune cells, and whatever the nose “catches” from the air (dust, pollen, microbes). It is a kind of biological filter. So it can be said that the nose acts as a biological filter protecting the respiratory system.

The “mini-vaccine” hypothesis

Canadian immunologist Scott Napper from the University of Saskatchewan became known for stating that eating one’s own mucus could act as a natural vaccine. According to his hypothesis, swallowing mucus containing microorganisms could “train” the immune system, teaching it to recognize potential enemies. It sounds convincing, but it is only a theory—not supported by any clinical studies.

Similarly, research conducted at Massachusetts Institute of Technology (MIT) showed that mucins (proteins found in mucus) may make it harder for bacteria to attach to tooth surfaces. Scientists even suggested that mucus could inspire the creation of bioactive protective coatings—but that is completely different from eating boogers.

What do doctors say?

Experts agree: there is no evidence that eating nasal discharge has a positive effect on immunity. However, there are potential health risks, such as:

  • bacterial infections (Staphylococcus aureus, Streptococcus pneumoniae),
  • damage to the nasal mucous membrane and bleeding,
  • transmission of germs from the hands to the mouth.

Doctors recommend teaching children to use tissues and wash their hands instead of explaining the behavior with “health” arguments.

Although the “mini-vaccine from the nose” hypothesis sounds interesting, science does not confirm its effectiveness. Eating boogers is simply a childhood habit that is worth eliminating over time. The immune system is better strengthened in traditional ways—through sleep, exercise, a healthy diet, and contact with nature, not with one’s own nose. 😄

Scientific sources and publications