What's the difference between probiotics and prebiotics?

Probiotics are live beneficial bacteria (yoghurt, kefir, fermented foods, supplements). Prebiotics are fibres that feed those bacteria (onion, garlic, banana, oats, legumes). Both support gut microbiome diversity, though specific health claims are often overstated.

Everyday sources cover both: curd, buttermilk, idli and dosa batter, and kanji for probiotics; onion, garlic, banana, oats, dal and whole grains for prebiotics.

For most healthy people a varied high-fibre diet does more for the microbiome than any supplement. Supplements are most justified for specific situations like antibiotic-associated diarrhoea.