The human microbiome

The human body is traditionally considered to be made up of some 10,000,000,000,000 cells, the basic building blocks of all life. But your body, if it is typical, has living in (or on) it, ten times more microorganisms (mostly bacteria) than cells. Although we are used to thinking that bacteria cause disease and need to be eradicated using antibiotics, it is now widely accepted in the scientific community that the microorganisms that have established themselves permanently in your body, your normal microbiota or flora, rather than causing problems may actually serve a useful purpose. As a simple example, E. coli bacteria living in the large intestine produce vitamin K and some of the B vitamins which can then be absorbed into the bloodstream and utilised by the body. Amongst the general public, the perceived importance of gut bacteria underlies the current trend of ingesting probiotics in the form of various drinks or yoghurts. Medical professionals are also increasingly likely to recommend taking probiotic pills in conjunction with, or after, a course of antibiotics, to help restore normal gut flora.

The Human Microbiome Project was established in 2008 by the US National Institutes of Health to identify the microorganisms that are found in both healthy and diseased humans and to “explore the relationship between disease and changes in the human microbiome”. In mid-2012, they announced that based on samples from over 200 men and women, they had established a reference database containing what is considered to be a normal human microbiome. Subsequent research has uncovered links between abnormal microbiota and problems as diverse as chronic sinus infections, intestinal ailments and obesity. The documentary “The Autism Enigma”, aired in Australia on ABC’s Four Corners last year, explored the idea that diet and antibiotic use may have disturbed the normal gut flora in some children with autism. In the future, maybe treatment of disease may focus on re-establishing normal flora in an affected part of the body using some sort of probiotic strategy, as well as, or even instead of, the traditional antibiotic strategies.

And if you’ve ever wondered how our hunter-gatherer ancestors managed without dentists, it has now been shown that, due to their different diet, they had different bacteria in their mouths and therefore, fewer problems with decaying teeth.