have you ever wondered what it means to be human well it turns out that only a tiny percentage of what you and I are made of is in fact human and we need these non-human bits to survive but we're doing Dreadful things to this hidden majority and it's damaging our health in ways that we are only just discovering it is said that we are 10 parts microb and one part human and that's counting microbial cells as the unit if we count unique genes uh then the difference is a factor of a 100 we are only 1% human in terms of unique genes so you and I are mostly bacteria of some kind we need each other to stay healthy and there's now a name for this part of ourselves the human microbiome is a set of microbial communities that have co-evolved with us and we with them um and have become part of the human landscape it is um an extension of self they provide to us Untold functions that we don't have the means of executing we're born deficient in our ability to digest certain kinds of food food stuffs for example the complex polysaccharides of plants we we can't manage those very well our microbes provide us the means of taking advantage they also help us manage lots of other encounters with the environment one of the things our microbiome does is give us an internal Shield of friendly microbes which protect us against Invasion by some of the nasties out there the good guys try to crowd out the bad ones it's competitive exclusion another term for it is colonization resistance so you know they man the beach head and make it hard for others to uh arrive and find Space so where are these microbes well while most are in our bow they can in fact be anywhere where we're exposed to the outside world so we have them in our mouth in the mouth it's a it's a measly 10 million per per gram but it's it's only measly because in the in the colon we're talking about 100,000 times as many per gram so the microbes in our bow for example help us to recirculate valuable nutrients and in fact assist us to keep our cholesterol down so we need them and they need us but we do some terrible things to our microbiome like assaulted with antibiotics yeah unfortunately for us and for them everything I'm going to tell you about the untour effects of antibiotics has to be balanced against the obvious important benefits but I think for too long we have felt as though you can't do much wrong with an antibiotic so if in doubt pull it out and that clearly is not a good position to be taken we've been asking volunteers to to take an antibiotic even though they didn't really need it we do it for short periods of time we we watch them before we watch them after and we're now doing second exposures a half year later and the bottom line is maybe not surprisingly far more members of the microbial communities of the human body experience a severe um impact they're decimated many more than we thought now in healthy people who might only have an occasional course of antibiotics the microbiome seems to recover quite well that's not so true in people who are sick and weakened as a side effect of antibiotics they can become infected with a germ called clostridium defil which causes hundreds of thousands of deaths worldwide so you're right so claustrum defal is the cause of large numbers of of deaths but even larger numbers of of um illnesses where there is a recovery but but after some cost one solution that some people suggest for this Devastation to our microbiome is probiotics substances which put back the friendly bacteria the evidence on probiotics is um still early uh to interpret but I would say um it's suggestive that there is some potential benefit there as I said before these friendly bugs our microbiome does a lot more than protect us against n the infections they keep our cholesterol down and detoxify poisons so the question is if we damage our microbiome with antibiotic overuse are we causing heart disease and cancer short answer is we don't know because no one has looked for this particular Link in the story We simply don't know so while in the past we've seen bacteria as the enemy and got excited about how we can kill off disease causing germs with antibiotics it's time for a new way of thinking remember we're talking about 99% of what we are