Dr. Charu Kaushic
Scientific Director, Institute of Infection & Immunity, Canadian Institutes of Health Research (CIHR)
If you have ever stopped at the refrigerated section in the health food section of your grocery store, you will have seen a wide selection of products like pre-and pro-biotics. Television commercials tout the benefits of these products on your gut health and microbiota. But what exactly is the microbiota, how is that different from the microbiome and why do we need to learn more about it through research?
Humans have an estimated 100 trillion microbes such as viruses, fungi and parasites, but the most predominant microbe living on and within our bodies are the bacteria. Together, these bacteria help form the human microbiota, and the genome of all the bacteria which live within our bodies help form the human microbiome — however, these terms are often used interchangeably. While a large majority of these bacteria reside in the gut, our skin, mouth, lungs, and reproductive and urinary tracts also have distinct microbiotas. Similar to fingerprints, each individual has unique communities of microbiota that are distinct for each person.
The relationship between humans and their microbiome is dynamic and complex. The microbiome begins to develop at birth as the baby passes through the vaginal canal and subsequently through breast milk, and it changes quickly in the early years following exposure to new environmental factors. While it does somewhat stabilize after this point, the microbiome can fluctuate throughout life depending on diet, health, exercise, hormonal balance, and environmental exposures. Many of the bacteria found within the microbiome exist in symbiosis with humans, meaning there is some benefit to both humans and the bacteria. Conversely, there are also pathogenic bacteria that can cause potential harm. Typically, in a healthy state, both symbiotic and pathogenic bacteria co-exist without any concern. However, a disturbance in this fine balance, also known as dysbiosis, can result in disease or illness.
The discovery of this hidden world of bacteria that lives within us and our increased understanding of how they influence our health is arguably one of the most exciting developments in health research in the last two decades. For instance, we now know that a person’s microbiome may influence their susceptibility to certain infections and contribute to illnesses such as diabetes, Crohn’s disease, Alzheimer’s, obesity, and anxiety. This is because the microbiome plays a key role in a diverse range of vital processes, including programming the immune system, controlling inflammation, defending against pathogens, providing nutrients to cells, facilitating metabolism, synthesizing vitamins, and even influencing behaviour by indirectly modulating the central nervous system.
We’re only beginning to understand the widespread impacts of the microbiome. The next phase of research will be exciting as we start to understand why and how different bacteria differentially affect our bodies and how we can manipulate the microbiome to improve human health.
This article was created by the Institute of Infection and Immunity, Canadian Institutes of Health Research (CIHR).