Harvard researchers just discovered not only 54 bacterial species previously unknown to be living in our bodies, but networks of viruses, fungi, and archaea that help in everyday human functioning by providing nutrients and fighting infections.
The study, published in Nature, sought to establish a baseline for the North American "microbiome," or the trillions of microscopic organisms in every corner of your body.
While the study provides us with the best understanding to date on our microbiome, the paper says that "the full complement of extant microbial genes has not yet been sequenced."
Basically, we still don't know exactly what's living inside us.
Harvard researchers collaborated with the Human Microbiome Project, which aims to understand the relationship between human health and this cohort of microorganisms. Using 1,631 body samples from 18 different sites in women and 15 in men, they determined which species make up individual microbiomes on the body (say, the microbes that live in your stomach versus the ones that live in your nostril) and how these microbes communicate with human cells and with each other.
Disordered microbiota have been linked to a host of diseases and conditions, including IBS, Type 2 Diabetes, anxiety and depression, autism, and preterm birth—but we're still years away from harnessing this knowledge for medical treatments.
Lead author Jason Lloyd-Price, postdoctoral fellow at Harvard T.H. Chan School of Public Health, told me that while there's huge potential for individualized therapies targeting the microbiome, they aren't possible until we understand it completely.
"If we're going to craft a therapy targeting the microbiome, we have to take into account the features that makes each individual person's microbiome unique," he said. "This is a microbiome when it's supposedly working in healthy people—so how does it go wrong? Then, we can ask, 'how do we fix it'?"
As one example, an increasing amount of research and testing has recently been put into fecal transplant research.
For severe Clostridium difficile bacterial colon infections, some doctors will insert (often frozen) feces from a healthy person into the intestines of someone with the infection. The microbiota in the healthy poop then fight off the invasive bacteria.
While fecal transplants could be used to help other gut conditions, like IBD, IBS, or metabolic syndrome, treating Clostridium difficile infections is its only legal use. Feces is technically classified as a "drug," so its medical use is strictly regulated. Until there's evidence that fecal transplants treat other conditions as well as Clostridium difficile infections, fecal transplants will remain relatively rare.
"One of the major drawbacks here, of course, is that we're limited to North American population," he said. "We definitely want to see these kinds of things for other populations around the world."
People should naturally care about their microbial "travellers," he said.
"There's a lot to be interested in the human microbiome," he said. "These [microorganisms] are with you for life, and they impact you in numerous ways. We should be be very thankful that they're there, and we should try to nurture them."