Separating Signal from Noise
The gut microbiome is one of the most researched areas in human health. It is also one of the most overhyped. Understanding what the evidence actually supports — versus what is marketing — is genuinely difficult.
What We Know With Confidence
- Fibre diversity drives microbiome diversity. Eating 30+ different plant foods per week is among the most evidence-backed dietary targets.
- Fermented foods (kefir, kimchi, sauerkraut, live yoghurt) measurably increase microbiome diversity in randomised trials (Wastyk et al., 2021, Cell).
- Antibiotic use significantly disrupts the microbiome; recovery takes 6–12 months and may be incomplete.
- Ultra-processed food consumption is negatively correlated with microbiome diversity in large cohort studies.
What's Still Uncertain
Probiotic supplements have weak evidence for healthy people. The microbiome is highly individual, making general supplement recommendations poorly supported. Claims about the gut-brain axis are promising but mechanistically complex.
The Practical Bottom Line
Eat more plants, more variety, and more fermented foods. These interventions have the best evidence-to-cost ratio of any gut health strategy. Our Anti-Inflammatory Food Scorer helps you track how well your daily diet supports this goal.