The bacteria living on and within you make up your microbiome, and this can weigh up to 6 pounds! While commonly ignored in the past, science is beginning to class this collection as effectively an additional organ, able to significantly impact on your health and wellbeing.
The bulk of these live within your intestines, contributing to digestion among other things. Recent research has found they actually produce neurochemicals along with a multitude of other molecules that are absorbed through our gut (some of these are same transmitters we use, such as dopamine, serotonin and GABA). In fact, prevalence of certain species has been linked to depression, anxiety and other metabolic disorders.
New evidence and ongoing research is suggesting that many conditions may be associated with differences in gut microbiome populations, and as such can be treated potentially with less invasive procedures. This field may still be in its infancy, but as we learn more, it may prove to be integral to overall health - and a key player when it goes wrong.