Bacteria overwhelmingly outnumber eukaryotes and archaea in the human microbiome by 2–3 orders of magnitude [7,8]. We therefore sometimes operationally refer to the microbial cells in the human body as bacteria. The diversity in locations where microbes reside in the body makes estimating their overall number daunting.

Is there more bacteria than cells?

There are more bacterial cells in your body than human cells, but the ratio isn't as extreme as once thought. A 2016 study at the Weizmann Institute of Science in Israel found that our total cell count is 56 per cent bacteria (compared with earlier estimates of 90 per cent).

Do bacterial cells outnumber human cells?

It's often said that the bacteria and other microbes in our body outnumber our own cells by about ten to one. That's a myth that should be forgotten, say researchers in Israel and Canada. The ratio between resident microbes and human cells is more likely to be one-to-one, they calculate.