I often tell my patients that health begins in the gut. It is not a metaphor: most of our immune system lives there, in constant dialogue with the microorganisms that share our bodies.
The gut microbiome — the trillions of bacteria, fungi and viruses that populate our digestive tract — is today one of the most fascinating fields in medicine. Far from being mere passengers, these microbes help digest food, produce vitamins and short-chain fatty acids, and continually teach the immune system to tell friend from threat.
When this balance is disturbed — a state we call dysbiosis — the consequences can reach far beyond the gut. Research has linked microbiome alterations to autoimmune disease, allergies, metabolic disorders and even mood, through the so-called gut-brain axis. A compromised intestinal barrier allows molecules through that keep the immune system in chronic alert.
This is why, in my approach, caring for the gut is caring for immunity. A diverse diet rich in plant fibre, fermented foods, less sugar and ultra-processed food, and judicious use of antibiotics are simple yet powerful foundations. Nourishing our microbes is, ultimately, nourishing ourselves.
Selected references
Belkaid Y, Hand TW. Role of the microbiota in immunity and inflammation. Cell. 2014;157(1):121–141.
Valdes AM, et al. Role of the gut microbiota in nutrition and health. BMJ. 2018;361:k2179.
Cryan JF, et al. The microbiota-gut-brain axis. Physiological Reviews. 2019;99(4):1877–2013.
