Prebiotic Foods vs Prebiotic Supplements: What Whole Foods Provide
What counts as a prebiotic, which foods are named as sources, what trials of isolated prebiotic fibers measured, and where the evidence comparing foods with supplements is missing.
Content last updated . This page has not been medically reviewed.
Quick answer
A prebiotic is defined as a substrate that is selectively used by host microorganisms and gives a health benefit. [1] Foods such as onions, garlic, bananas, chicory root and Jerusalem artichokes contain prebiotics, but ISAPP says typically at low levels. [2] Trials of isolated prebiotic fibers mostly measure changes in gut bacteria, which is not the same as feeling better. Direct comparisons of whole foods against prebiotic supplements for health outcomes: Proper evidence not found (see below). Information only, not medical advice.
Read this first
Prebiotic foods and fibers are fermented by gut bacteria, which can cause gas, bloating and cramps; MedlinePlus advises adding fiber gradually. [3] People with irritable bowel syndrome, bowel narrowing, inflammatory bowel disease, or a bowel blockage should ask a clinician before adding concentrated prebiotics; see fiber and prebiotic cautions. Severe belly pain with vomiting, blood in stool or fever needs urgent care (911 in the US). Pregnancy, children, kidney or liver disease, interactions and surgery are not covered in the sources we read for this topic, so ask a clinician or pharmacist; see medication interactions and supplements before surgery.How the sources define the terms
ISAPP's 2017 consensus statement requires that beneficial health effects be documented for a substance to count as a prebiotic. [1] ISAPP's resource page adds that most studied prebiotics are specific types of fiber, and that not all dietary fibers are prebiotics. [2] So "high in fiber" does not automatically mean "prebiotic", and a food that contains a prebiotic fiber has not necessarily been tested as a prebiotic. For the full definitions see prebiotics, synbiotics and postbiotics defined.What research found
| Question | What the source found | Strength of evidence |
|---|---|---|
| Do chicory-derived inulin-type fructans raise Bifidobacterium? | In 50 trials (2,525 people) at 3 to 20 g a day, abundance rose; trials covered foods and supplements [4] | Biomarker only |
| Do they help bowel function? | Beneficial effects in healthy people in the same review [4] | Promising |
| Do they help chronic constipation? | Inulin, fructo-oligosaccharide and polydextrose graded "insufficient evidence" [5] | Insufficient |
| Does whole-food fiber relate to disease? | Lancet reviews: observational data suggest 15 to 30% lower mortality and disease incidence for the highest fiber eaters vs lowest; trials showed lower body weight, blood pressure and total cholesterol; supplement trials were excluded [6] | Moderate certainty for fiber, food-based |
| Do prebiotic foods beat supplements, or the reverse? | Proper evidence not found | Not available |
In the first row, "biomarker only" means a bacteria count changed; the review does not show that was the cause of any health benefit. [4]
Evidence head-to-head
Proper evidence not found. We searched PubMed for reviews and trials comparing prebiotic-rich whole foods with isolated prebiotic supplements on health outcomes and read none. Amounts of prebiotics in specific foods were also not given in the sources we read beyond ISAPP's "low levels" statement, so we publish no food amounts here. [2]Foods named in the sources
ISAPP names onions, garlic, bananas, chicory root and Jerusalem artichokes. [2] A low-FODMAP review names onion, garlic, shallots and legumes among major high-FODMAP sources, which matters because the same foods can trigger symptoms in some people with IBS. [7] The NHS lists oats, wholegrain bread, brown rice, nuts and fruit among fiber-rich choices, [8] and NICE (IBS guidance) says people with wind and bloating may find oats helpful. [9] See probiotics, prebiotics and fermented foods, oats, legumes and low-FODMAP diet.Supplements: what to know
Prebiotic supplements (inulin, fructo-oligosaccharides, galacto-oligosaccharides) are isolated fibers. The review of chicory inulin-type fructans found bifidogenic effects in healthy people and in several health-impaired groups, but not in people with gastrointestinal disorders. [4] If you have a gut condition, that distinction matters. See prebiotic fibers, inulin and chicory root fiber, prebiotics vs probiotics and quality testing.Frequently asked questions
What is the difference between fiber and a prebiotic?
Most prebiotics are fibers, but not all fibers are prebiotics; a prebiotic must be selectively used by microbes and have documented benefit. [2] [1]
Which foods contain prebiotics?
ISAPP names onions, garlic, bananas, chicory root and Jerusalem artichokes, at typically low levels. [2]
Are prebiotic supplements better than food?
Proper evidence not found. We read no head-to-head comparison on health outcomes.
Do prebiotics cause gas?
Fiber can cause gas when intake rises quickly, according to MedlinePlus. [3] Fiber supplements overall were linked to more flatulence in a constipation meta-analysis. [10]
Are prebiotics the same as probiotics?
No. Prebiotics are substrates that feed microbes; probiotics are live microorganisms. See prebiotics vs probiotics.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Limits and no universal winner
Foods deliver prebiotic fibers together with other nutrients, at typically low levels according to ISAPP, [2] while the trials of isolated chicory fructans used 3 to 20 g a day. [4] We found no source that compares gas or symptom rates between the two approaches, and none that declares one better for health. A dietitian or clinician can help match food choices to your gut symptoms, medicines and conditions.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.