Probiotics are live microorganisms. Prebiotics are what certain beneficial microorganisms use as food, usually types of fiber your own body can't digest. One adds organisms; the other feeds the ones that can use it. Products that combine the two are often described as synbiotics.
The two words differ by a few letters, and that's caused a lot of confusion. Here's the difference, with the official definitions, where each one comes from, and how to tell them apart on a label.
What's the difference between prebiotics and probiotics?
The difference between prebiotics and probiotics is that probiotics are live microorganisms, while prebiotics are what certain microorganisms use as food. Probiotics provide a health benefit when taken in adequate amounts. Prebiotics are substances, mostly fibers, that beneficial gut microbes selectively use. Labels count probiotics in CFU and prebiotics in milligrams or grams.
Prebiotics vs probiotics at a glance
| Probiotics | Prebiotics | |
|---|---|---|
| What they are | Live microorganisms (bacteria, some yeasts) | Substances used by microorganisms, mostly fibers |
| Alive? | Yes | No |
| How labels count them | CFU (colony-forming units) | Milligrams or grams |
| Common supplement forms | Lactobacillus and Bifidobacterium strains | Inulin and other oligosaccharide fibers |
| Food sources | Some yogurts and kefirs with live cultures | Chicory root, onions, garlic, asparagus, whole grains |
What are probiotics?
The International Scientific Association for Probiotics and Prebiotics (ISAPP) defines probiotics as "live microorganisms that, when administered in adequate amounts, confer a health benefit on the host." Three parts of that definition matter: the organisms are alive, the amount matters, and there has to be a benefit shown for that organism.
Most probiotic supplements use strains from two groups, Lactobacillus and Bifidobacterium. Labels list the total count in CFU.
One clarification that trips people up: fermented food and probiotics aren't the same thing. Sourdough bread is fermented, but baking kills the microbes. Many shelf-stable pickles aren't fermented at all; they're made with vinegar. And even when a fermented food does contain live microbes, those organisms may not have been studied for a specific benefit. ISAPP treats "fermented foods" and "probiotics" as separate categories.
What are prebiotics?
ISAPP's 2017 consensus definition describes a prebiotic as "a substrate that is selectively utilized by host microorganisms conferring a health benefit." In plain terms: something your gut microbes can use as food, where that use is selective (it favors certain beneficial microbes rather than feeding everything) and linked to a benefit.
Not every fiber counts. A prebiotic has to meet the "selectively utilized" part.
Inulin-type fibers: chicory root and Jerusalem artichoke
The best-known prebiotics are inulin-type fructans: inulin and fructooligosaccharides (FOS). They pass through the small intestine without being digested and are fermented by bacteria in the colon, including Bifidobacterium.
Two of the richest natural sources are chicory root and Jerusalem artichoke (also called sunchoke). That's why you'll often see one or both in supplement fiber blends.
Food sources
You can also get prebiotic fibers from everyday foods: onions, garlic, leeks, asparagus, slightly underripe bananas, and whole grains such as wheat and barley. If you're new to these fibers, more isn't always comfortable at first. Fermentation in the colon produces gas, so some people notice bloating when they increase intake quickly. Building up gradually is a common approach.
What is a synbiotic?
ISAPP's 2020 consensus defines a synbiotic as "a mixture comprising live microorganisms and substrate(s) selectively utilized by host microorganisms that confers a health benefit on the host." In everyday terms, it's live cultures plus something gut microbes can use, combined in one product. Note the last part of the definition: under ISAPP's wording, the combination itself should be shown to provide a benefit. Simply putting the two in one capsule is how the term is often used in marketing, but it's not the full scientific definition.
Do you need both?
Not necessarily, and food comes first. Many people get prebiotic fibers from a diet rich in vegetables, legumes and whole grains, and live cultures from foods like yogurt or kefir that contain them.
Supplements are a convenience: a defined amount, every day, without having to plan meals around it. If you choose a supplement, read the label for the strains and CFU (for probiotics) and the fiber source and milligrams (for prebiotics).
If you're pregnant or nursing, have a medical condition, are immunocompromised, or take medication, check with your healthcare professional before starting a probiotic or prebiotic supplement.
How Nutriveska uses both
Both of our probiotic formulas combine live cultures with the same 250 mg organic prebiotic fiber blend from Jerusalem artichoke root and chicory root.
- Daily Probiotics for Men & Women: 50 billion CFU from six Lactobacillus and Bifidobacterium strains, plus the prebiotic blend, a 50 mg digestive enzyme blend, zinc and vitamin D3. One capsule daily. It's our daily probiotic with prebiotic fiber for adults.
- Women's Probiotics: 25 billion CFU from five strains, plus the prebiotic blend, 50 mg organic cranberry extract and 400 mg D-mannose. One capsule daily. See the women's probiotic with prebiotic fiber.
Probiotics and prebiotic fiber support digestive balance and a healthy gut microbiome as part of your routine.* Both formulas are gluten-free and third-party tested; Women's Probiotics is also vegan.
FAQ
Should you take prebiotics and probiotics together?
You can, and many products combine them. Whether you need a supplement at all depends on your diet and goals.
What foods are prebiotics?
Good sources of prebiotic fibers include chicory root, Jerusalem artichoke, onions, garlic, leeks, asparagus, slightly green bananas and whole grains.
Is inulin a prebiotic?
Yes. Inulin and related fructooligosaccharides are among the best-studied prebiotics. Chicory root and Jerusalem artichoke are rich sources.
Can prebiotics cause gas?
They can for some people, especially when intake increases quickly, because gut bacteria ferment them. Increasing gradually often helps. If symptoms persist, talk with your healthcare professional.
What is a synbiotic?
A product combining live microorganisms with a substrate that gut microbes selectively use. Under ISAPP's 2020 definition, the combination should be shown to provide a health benefit.
Is yogurt a probiotic?
Only some yogurts. Look for "live and active cultures" on the label. Not all fermented foods meet the definition of a probiotic.
These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.
Sources
- Hill C, et al. The ISAPP consensus statement on the scope and appropriate use of the term probiotic. Nat Rev Gastroenterol Hepatol. 2014;11:506–514.
- Gibson GR, et al. The ISAPP consensus statement on the definition and scope of prebiotics. Nat Rev Gastroenterol Hepatol. 2017;14:491–502.
- Swanson KS, et al. The ISAPP consensus statement on the definition and scope of synbiotics. Nat Rev Gastroenterol Hepatol. 2020;17:687–701.
- Marco ML, et al. The ISAPP consensus statement on fermented foods. Nat Rev Gastroenterol Hepatol. 2021;18:196–208.
- NIH Office of Dietary Supplements. Probiotics: Fact Sheet for Health Professionals.
