Why Gut Health Matters

The gut microbiome — the trillions of bacteria, fungi and viruses living in your digestive tract — influences digestion, immune function, mental health, inflammation and even weight regulation. A diverse microbiome is associated with better health outcomes across virtually every system in the body.

What Actually Works (Evidence-Based)

  1. 1

    Eat 30 different plants per week

    The American Gut Project found that people who ate 30+ different plant foods per week had significantly more diverse gut microbiomes than those who ate fewer than 10. This includes vegetables, fruits, grains, legumes, nuts, seeds, herbs and spices — each counts as one plant. This is more achievable than it sounds: a single meal with onion, garlic, tomato, spinach and two herbs is already 5 plants.

  2. 2

    Eat fermented foods daily

    A 2021 Stanford study found that a diet high in fermented foods increased microbiome diversity and reduced inflammatory markers. Include: yoghurt with live cultures, kefir, sauerkraut, kimchi, kombucha or miso regularly. Start small if you are not used to them — large amounts too quickly can cause temporary bloating.

  3. 3

    Prioritise dietary fibre

    Gut bacteria ferment fibre — it is their primary food source. Without enough fibre, beneficial bacteria populations decline. High-fibre foods: legumes (beans, lentils, chickpeas), oats, vegetables, fruits, wholegrains, nuts and seeds. Aim for 25–30g of fibre per day.

  4. 4

    Reduce ultra-processed foods

    Ultra-processed foods (packaged snacks, fast food, soft drinks, ready meals) are associated with reduced microbiome diversity. They are typically low in fibre and contain emulsifiers and additives that some research suggests disrupt the gut lining.

  5. 5

    Manage stress

    The gut-brain axis is bidirectional — chronic stress negatively affects gut bacteria composition and gut permeability. Exercise, adequate sleep, meditation and reducing chronic stressors all support gut health through this pathway.

  6. 6

    Avoid unnecessary antibiotics

    Antibiotics kill both harmful and beneficial bacteria indiscriminately. A course of antibiotics can reduce microbiome diversity for weeks to months. This is not a reason to avoid necessary antibiotics, but it is a reason not to take them for viral infections (where they have no effect anyway).

About probiotics supplementsThe evidence for probiotic supplements is mixed for healthy people. Food-based sources (fermented foods) appear to have more consistent benefits than most supplements, which vary widely in quality and strain specificity. Specific probiotic strains have strong evidence for particular conditions like IBS — consult a doctor or dietitian for personalised advice.

Frequently Asked Questions

Gut microbiome composition can change noticeably within 3–4 days of significant dietary changes. Meaningful, sustained improvement takes 4–8 weeks of consistent dietary changes. The microbiome is highly responsive to diet — it changes quickly in both directions.
Common signs: frequent bloating, irregular bowel movements, food intolerances, frequent illness (immune connection), fatigue, skin issues like eczema, and mood disturbances. These can have many causes — persistent symptoms warrant a conversation with a doctor.
Direct-to-consumer microbiome tests (like Microba or Viome) provide interesting data but currently have limited clinical utility — the science of precisely interpreting microbiome composition is still developing. They can be a useful motivational tool but should not replace medical advice for genuine gut health concerns.