The bodies of humans and most animals are populated by highly complex and genetically diverse communities of microorganisms. The majority of these microbes reside within the intestines in largely stable but dynamically interactive climax communities that positively interact with their host.
Researchers have found that stress can alter the balance of bacteria by changing the composition, diversity and number of intestinal bacteria. The communities of bacteria become less varied, and there are greater numbers of potentially harmful bacteria, such as Clostridium.
When the researchers reduced the number of bacteria in the intestines of laboratory mice using antibiotics, they found that some of the effects of stress on the immune system were prevented leading them to suggest that not only does stress change the bacteria levels in the gut, but that these alterations can, in turn, impact our immunity.
Because gut bacteria have been linked to diseases like inflammatory bowel disease, and even to asthma, a future goal of the study is to determine whether alterations of gut bacteria is the reason why these diseases tend to be worse during periods of pressure.