Rob Knight of University of California San Diego is a big player when it comes to the science of the gut microbiota. Yet by studying the microbial world living in and on human beings he says he has come to feel very, very small. In “Follow Your Gut”, the TED Book he co-authored with science writer Brendan Buhler about the science of the microbiome, Knight says, “The emerging facts about this tiny world serve as a rebuke to our egos.” That is, many of the things we thought humans had a grip on—from disease risk to certain behaviours—may be more under the control of our microbes.
Knight teamed up with Buhler to write “Follow Your Gut” as a follow-up to his 2014 TED talk, “How our microbes make us who we are”. The book seems to be a necessary complement to the talk: it allows readers to explore these ideas at a more comfortable pace than when they are packed into a seventeen-and-a-half minute lecture.
“Follow Your Gut” aims to give a complete overview, in broad strokes, of what we know about the gut microbiota. Short enough to be read in a single sitting, but long enough to develop analogies and explanations, this compact guide is Knight’s gift to the public. Throughout the book, Knight and Buhler manage to seamlessly introduce concepts in a way that makes sense even to those who are unfamiliar with the conventions of science. This friendly microbe of a book covers how we get our microbiome, how the microbiota affect both the body and the brain, different ways to ‘hack’ your microbiome, how antibiotics damage it, and then some thoughts about where all this is going in the future.
The book begins with a walk-through of the body, explaining the microbes at each site, and then focuses in on the gut. Knight emphasizes what we know about how infant guts become colonized by bacteria, and includes a now-famous personal story of surreptitiously swabbing his infant daughter with her mother’s vaginal microbes after birth by emergency caesarean section. (A recently published paper explored the use of a similar ‘vaginal seeding’ procedure in caesarean-born infants.)
Brief sections explain the links between microbes and several diseases and conditions (including obesity), as well as the gut-brain axis. The authors then use a ‘lawn’ analogy to explain four promising ways to change and protect the microbiome: prebiotics (fertilizing the lawn), probiotics (reseeding the lawn), fecal transplants (laying down new sod), and vaccines (preventative lawn maintenance). The vaccine idea is particularly novel. Knight argues that once scientists identify the bacteria responsible for triggering certain conditions—perhaps even something like depression—we could take advantage of the specificity of vaccines to protect ourselves from the bacterial culprit or culprits.
Knight emphasizes growing documentation of harm from antibiotics: he says they are so ubiquitous that they are incorporated into many medical procedures (like those surrounding the birth of a child) without always being disclosed. He argues that their harm may not be negligible. An illustration in the book shows a plane dropping antibiotics as bombs, decimating microbes both bad and good.
The book ends on the same point as Knight’s TED Talk: the need to develop “a kind of microbial GPS—a guiding body of knowledge that will tell us where we are, as well as where we want to go and how to get there.” We still have a lot to learn in order to reach this goal, and Knight is one of the scientists leading the charge.