The contact with pets reduces the risk of allergies in children. Why this happens explain the researchers: dogs bring a variety of external bacteria into the house that help strengthen the immune system of children. Without exposure to a variety of bacteria, the immune system does not learn correctly which bacteria are dangerous and which are harmless. This is why many studies show that children born in families with significant exposure to animals have fewer cases of asthma and allergies.
A Canadian study published in Microbiome found that pets help children accumulate two types of bacteria in the gut associated with a lower risk of allergies and obesity . By analyzing stool samples from 746 children, the researchers found that contact with house dogs and cats during pregnancy and early childhood was associated with higher levels of two intestinal microorganisms: Ruminococcus and Oscillospira, linked to a lower probability of develop allergies and obesity respectively.
According to the researchers, the study shows that some bacteria are more common in the intestinal flora of children born in houses where animals live and, in general, it is believed that greater diversity and richness of the intestinal bacterial flora can help protect the child from diseases related to immune system.
However, the same is not true in the case of the elderly : the help of dogs to the immune system is in fact decidedly stronger in youth. The University of Arizona in Kelly recently conducted a study on the elderly (50 to 80 years old) taking into account the effect of contact with dogs. Research showed that after 3 months there had been no changes in the subjects’ microbiomes.