Reviewed by Jessie, BSc Biomedical Science · Formulation Lead, Purest Kids
TL;DR — Probiotics are live beneficial bacteria. Prebiotics are the fibres that feed those bacteria. They work as a team: adding good bacteria helps more if you also feed them. Most prebiotics come from everyday foods (onions, bananas, oats, legumes), so for many kids, diet does a lot of the work. Products combining both are sometimes called "synbiotics."
The garden analogy that makes it click
If your child's gut is a garden:
- Probiotics are the seeds — the live, helpful bacteria you're adding.
- Prebiotics are the fertiliser — the specific fibres that feed those bacteria so they can grow and thrive.
Planting seeds in poor soil gives you a weak garden. Fertilising soil with no good seeds doesn't help much either. The two together are what makes the garden flourish — which is exactly why you increasingly see them combined.
Probiotics: the live bacteria
Probiotics are specific strains of live bacteria (and sometimes yeasts) that, in adequate amounts, may confer a health benefit. In children, the better-evidenced uses include supporting the gut during antibiotic courses and certain digestive situations. They're measured in CFU — colony-forming units.
Prebiotics: the food for those bacteria
Prebiotics are types of fibre the human body can't digest itself, but the helpful gut bacteria can ferment for fuel. Common examples include inulin and FOS (fructo-oligosaccharides). The everyday food sources are reassuringly ordinary:
- Bananas (especially slightly under-ripe)
- Onions, garlic, leeks
- Oats and whole grains
- Beans, lentils, and other legumes
For a child eating a varied, fibre-rich diet, a good amount of prebiotic intake happens naturally at the dinner table.
"Synbiotics": the two combined
When a product contains both probiotics and prebiotics, it's sometimes called a synbiotic. The logic is straightforward — you supply the bacteria and the food they need to establish themselves, rather than hoping the child's diet provides enough fuel.
What this means practically
- Food first. Fibre-rich, varied meals deliver prebiotics naturally and feed whatever bacteria are already there.
- Probiotics are situational. They make most sense for specific reasons (e.g. around antibiotics) rather than as a guaranteed daily essential for every healthy child.
- Combining them is sensible when supplementing, because bacteria do better when they're fed.
Where Purest Kids fits
Our Daily Pre+Probiotic Melts Kids are built on this team-up: probiotics plus prebiotics in one daily melt, so the beneficial bacteria arrive with some of the food they need. We still encourage fibre-rich meals as the foundation — a supplement complements a good diet, it doesn't replace one.
Further reading
- ISAPP: definitions of probiotics, prebiotics, and synbiotics
- Canadian Digestive Health Foundation: prebiotics and fibre
- NIH Office of Dietary Supplements: Probiotics
Educational only; not medical advice.