The human microbiome is a vast array of microbes and microorganisms that live on and in our bodies, creating a community of symbiotic, commensal and pathogenic bacteria, all of which call our bodies home. These various communities exist in unique, complementary combinations, inhabiting everything from our skin to our genitals, our mouths and eyes and, of course, our intestines.
For every one human gene we have in our bodies, there is likely an associated bacterial gene within our microbiome. More than 100 trillion microorganisms live in our gut, mouth, skin and other mucosal surfaces of our bodies. These microbes have numerous beneficial functions relevant to supporting life such as digesting food, preventing disease-causing pathogens from invading the body, and synthesizing essential nutrients and vitamins. With the advancement of genomic technologies, the capacity of this second genome to influence health and disease can now be harnessed.
While study of what is now known as the human microbiome can be traced as far back as Antonie van Leeuwenhoek (1632–1723), recent advances in genomics and other areas of microbiology have spurred a resurgence of interest. That interest has uncovered evidence of associations between the microbiome and disease across a diverse range of conditions including skin diseases like eczema and psoriasis, GI tract diseases such as Crohn’s disease, inflammatory bowel disease, and ulcerative colitis, urogenital conditions like bacterial vaginosis, and recurrent infections like C. difficile. The role of the microbiome in maintaining health is also a keen area of interest, with substantial work being done to understand the impact of alterations in the infant microbiome on lifelong health and how our individual micro biomes may directly influence our weight and mental health.