Drugging the gut microbiome

We now know that each of us is, in some respects, more microbe than human. Each human body is colonised by as many as 100 trillion microbes: rather more, in fact, than our own cells, and contributing about 2kg to an adult’s body weight. There are microbial colonies on and around many organs but the gut, and particularly the colon (or large intestine) carries the greatest microbial load. The greatest proportion of these are bacteria and viruses, but the colonies also include large numbers of parasites and single-celled eukaryotes. The bacterial fraction is the best understood: we know so little about 80% of the viruses that inhabit our guts that they have been collectively termed ‘viral dark matter’.

Before the genome era, however, we understood less still about the bacteria in our guts. One of the most remarkable features of the human gut microbiome is its diversity. It is clear that if we are to target the microbiome successfully we first need to understand the microbial chemistry that plays a vital role in digestion and in sustaining a healthy, fully functioning immune system. The simplest way of improving your microbiome is by altering your diet, and some companies are figuring out ways of providing dietary advice in a precise and even personalised way. It is possible to target the microbiome with small-molecule drugs, however, if it is done indirectly with compounds that inhibit the enzymes found in gut bacteria.