How many bacteria are in the human body?

A 2016 recount estimated about 38 trillion bacterial cells in a 70 kg man, against about 30 trillion human cells. That is a ratio near 1:1, not the '10 to 1' figure repeated for decades. Most of the bacteria live in the colon and weigh about 200 grams in total. The gut microbiome's genes outnumber human genes more than 100-fold.

Source: Sender, Fuchs & Milo (2016), PLOS Biology and Cell