Beneficial gut bacteria thrive on dietary fibre, which they ferment to produce those vital short-chain fatty acids mentioned earlier. Foods rich in prebiotics—essentially food for your good bacteria—include onions, garlic, leeks, asparagus, bananas, oats, and Jerusalem artichokes. Fermented foods like yoghourt, kefir, sauerkraut, kimchi, and kombucha introduce live beneficial bacteria (probiotics) directly into your system, helping to maintain microbial diversity.