Probiotics vs Prebiotics: What's the Difference?

Probiotics and prebiotics sound almost the same and are often confused, but they do different jobs. The simplest way to remember it: probiotics are beneficial microbes, while prebiotics are the food that feeds them. Both can support a healthy gut, mostly through everyday foods rather than supplements.

Probiotics: the beneficial microbes

Probiotics are live bacteria (and sometimes yeasts) that, in adequate amounts, may benefit your gut. You'll find them naturally in fermented foods:

• Yogurt with live cultures
• Kefir
• Sauerkraut and kimchi (unpasteurized)
• Miso and tempeh

Probiotic supplements also exist, but effects are strain-specific and not all products are well studied. Food sources are a sensible starting point for most people.

Prebiotics: the food for your microbes

Prebiotics are types of fiber your body can't digest but your gut bacteria can. By feeding beneficial bacteria, they help them thrive. Good sources include:

• Onions, garlic, and leeks
• Oats and barley
• Bananas (especially slightly underripe)
• Legumes, asparagus, and Jerusalem artichoke

Do you need supplements?

For most healthy people, a varied diet with fiber and some fermented foods covers both. Supplements can have a role in specific situations — for example, alongside certain antibiotics or conditions — but that's best discussed with a doctor or pharmacist rather than assumed.

What the evidence says

Research on probiotics is promising but mixed, and effects depend heavily on the specific strain and the person. Prebiotic fiber, as part of overall fiber intake, has more consistent support. The reliable takeaway is to feed your gut with plenty of varied, fiber-rich plants.

Track what helps with PoopID

If you try adding fermented or prebiotic foods, watch the effect. PoopID records your Bristol type and frequency from a photo. See the diet and gut health guide for the full picture.

• Sources:
• NIDDK — Eating, Diet & Nutrition. niddk.nih.gov
• NHS — Probiotics. nhs.uk