&gt;doesn&#x27;t have the entire picture<p>I think it&#x27;s pretty early days still in figuring what&#x27;s going on. Until fairly recently they only had a pretty hazy guess what bacteria were in you. Apparently less than 1% of gut bacteria can be cultured outside the body.<p>Things are changing recently with cheap gene sequencing and big data analytics. I think they basically take a sample, mush it up, run it through a gene sequencer and use computer algorithms try to make some sort of sense of the data. The Human Microbiome Project (2008-2013) calculated there are more than 10,000 microbial species in humans. Quite a lot to look at.