According to the fascinating book Gut by Giulia Enders, researchers in Heidelberg, Germany, used cutting edge technology to discover that there are three types of gut bacteria and, therefore, three different types of human gut.
These three types (or families as Giulia calls them) are:
and they are distributed amongst Europeans, Asians and Americans whatever their gender or age.
Giulia recounts that some practitioners of Traditional Chinese Medicine were visiting Heidelberg when this discovery was made. They highlighted how modern medicine was now supporting classical Chinese medical theory, which has always divided people into three groups, depending upon how they react to certain medicinal plants – like ginger.