In 1826, the genial French gastronome Brillat-Savarin penned the phrase “Tell me what you eat, and I will tell you what you are.”
Two hundred years later, pathbreaking research suggests that what we eat doesn’t just give us fuel and pleasure but also feeds the trillions of microbes in our gut microbiome, and thus constitutes one of the most consequential interactive exposures we have to our environments.
The science behind microbiome – a term used to describe the genome of all the microorganisms living in and on all vertebrates - is still in its infancy but is already helping unpack mysteries related to diet-related non-communicable diseases such as cancer and diabetes, and even to our moods. It suggests that metabolism may best be understood not as a factory process turning food into dietary energy, but a complex regulatory interface mediated by microorganisms whose function is tantamount to that of a human organ like the heart or liver.
“It’s not only about us,” says Fanette Fontaine, a microbiologist who is producing some benchmark reports for FAO on the subject. “We are walking ecosystems.”
The gut microbiome weighs as much as our brains and hosts about 1 000 different species of bacteria, with high variability as only one-sixth of these are typically found in the majority of individuals.
Thanks to the development of rapid and affordable genomic sequencing technologies, we can now identify the presence and function of a huge array of bacteria, viruses, protozoa and fungi as well as their theater of action. It turns out that many of these creatures, once feared as potentially dangerous invasive germs, perform roles that train our immune systems and influence various brain and bodily functions central to healthy lives.
It’s now clear that some gut microbiomes foster obesity - even when calorie intake wouldn’t predict it - while others correlate strongly to Type 2 diabetes, cardiovascular diseases, asthma, allergies and childhood stunting.