Gut Microbiome

Your gut bacteria are a metabolic organ in their own right, and what you feed them decides what they make. The pathway runs as a sequence — prebiotic → probiotic → postbiotic. Prebiotic fibre (inulin, resistant starch, β-glucan) and polyphenols are the substrate; the live cultures in fermented foods (yogurt, kefir, kimchi, sauerkraut, kombucha, miso, tempeh) are the bacteria themselves, dosed in colony-forming units (CFU) rather than milligrams. When those bacteria ferment fibre they produce postbiotics — short-chain fatty acids like butyrate, propionate, and acetate — which fuel the cells lining the colon, tighten the gut barrier, calm inflammation, and signal outward to the immune system and the brain along the gut-brain axis. Fibre diversity and regular fermented foods build the community; a low-fibre, ultra-processed diet and broad-spectrum antibiotics tear it down. There is no RDA for CFU or prebiotic grams, so this pathway scores the one input that does have a target — fibre — and surfaces the live cultures and polyphenols beside it as named contributors.