Fermented Foods vs Probiotic Supplements
Fermented foods and probiotic supplements are not the same thing. Definitions from an expert panel, what trials of supplements found, safety points, and where evidence is missing.
Content last updated . This page has not been medically reviewed.
Safety first. Supplements can cause side effects and interact with medicines. Read mushroom safety and interactions before you use any mushroom product.
Short answer: a fermented food and a probiotic supplement are different things, and a result for one does not transfer to the other. We did not find a trial that compared fermented foods directly with probiotic supplements for a health outcome. Proper evidence not found for that comparison: we searched PubMed for fermented foods compared with probiotic supplements and read the sources below.
How the sources define the terms
- Fermented foods are defined by an ISAPP expert panel as foods and beverages made through desired microbial growth and enzymatic conversions of food components. [1]
- Probiotics are defined as live microorganisms which, when administered in adequate amounts, confer a health benefit on the host. [2]
- NCCIH notes probiotics can be found in yogurt and other fermented foods, dietary supplements, and beauty products. [3]
So a fermented food may or may not contain live microorganisms, and the definition of a probiotic requires a benefit to be shown. A fermented food counts as probiotic only if it meets that definition. The panel statement that makes this distinction is cited above. [1]
What the research found
| Question | What the source found | Strength of evidence |
|---|---|---|
| Probiotic supplements for irritable bowel syndrome | A network meta-analysis (54 trials of probiotics) found improvement in IBS symptoms, particularly with Bifidobacterium and Lactobacillus strains, but the most effective combination or strain remains unclear. [4] NCCIH describes a 2018 review of 53 studies that could not identify which strains are most likely to help. [3] | Promising but limited; strain specific |
| Fermented foods: yogurt | A systematic review of 108 studies concluded a causal relationship for lactose digestion and tolerance; other links were associations. [5] | Lactose: established; others observational |
| Fermented foods: kefir | A review of 16 trials found limited evidence, safety assessed in only 5 of 18 publications and 12 studies at high risk of bias. [6] | Insufficient evidence |
| Fermented foods: sauerkraut | An 87-person crossover trial found changes in single bacterial species; the authors said the healthy gut microbiome is rather resilient to short-term dietary change. [7] | Insufficient evidence for health outcomes |
| Head-to-head, food vs supplement | Proper evidence not found. | None |
The supplement trials tested specific strains of probiotics; the food studies tested foods that contain many microbes plus milk, vegetables and salt. Different products, different questions.
No universal winner
A clinician, dietitian or pharmacist can say whether either suits a particular person, especially with a health condition, medicines or pregnancy.Frequently asked questions
Are fermented foods probiotics?
Not automatically. Fermented foods are defined by microbial growth and enzymatic conversion; probiotics are live microorganisms shown to confer a health benefit. [1][2]
Do probiotic supplements work?
For irritable bowel syndrome a network meta-analysis found symptom improvement, particularly with Bifidobacterium and Lactobacillus, but could not say which strain is best. [4] Results are specific to the strain and condition.
Which is safer?
We did not find a comparison. NCCIH says harm from probiotics is more likely in people with severe illness or weak immunity. [3]
Can I get probiotics from yogurt?
NCCIH says probiotics can be found in yogurt and other fermented foods. [3] Whether a given yogurt qualifies depends on the product and its label.
Should I stop a medicine or supplement for this?
Never change a prescribed medicine without asking the prescriber or pharmacist. See Medication interactions.
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.
Safety and who should ask a clinician
- Serious illness or weakened immunity. NCCIH says the risk of harmful effects from probiotics is greater in people with severe illnesses or compromised immune systems. [3]
- Premature infants. NCCIH reports cases of severe or fatal infections in premature infants who were given probiotics, and says the FDA has warned health care providers about this risk. [3] See Probiotic safety.
- Possible harms listed by NCCIH: infections, production of harmful substances by the microorganisms, and transfer of antibiotic resistance genes. [3]
- Label accuracy. NCCIH says some probiotic products have been reported to contain microorganisms other than those listed on the label. [3] See Quality testing and certifications.
- Regulation. NCCIH says that, depending on intended use, the FDA might regulate a probiotic as a dietary supplement, a food ingredient or a drug. [3]
- Fermented food cautions are different: biogenic amines (histamine, tyramine) can occur in some fermented foods. [8] MAOI users should ask the prescriber or pharmacist. See Histamine, tyramine and fermented foods.
- Raw or unpasteurized dairy is advised against in pregnancy by a university extension fact sheet. [9]
Limits and uncertainty
References
- Salminen S, et al. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on fermented foods. 2021. PubMed 33398112. Read 2026-10-22.
- Hill C, et al. Expert consensus document. The ISAPP consensus statement on the scope and appropriate use of the term probiotic. 2014. PubMed 24912386. Read 2026-10-22.
- National Center for Complementary and Integrative Health (NCCIH, US). Probiotics: Usefulness and Safety. Read 2026-10-22.
- The efficacy of probiotics, prebiotics, synbiotics, and fecal microbiota transplantation in irritable bowel syndrome: a systematic review and network meta-analysis. 2024. PubMed 38999862. Read 2026-10-22.
- Yogurt, cultured fermented milk, and health: a systematic review. 2021. PubMed 32447398. Read 2026-10-22.
- The effects of kefir consumption on human health: a systematic review of randomized controlled trials. 2023. PubMed 35913411. Read 2026-10-22.
- The impact of regular sauerkraut consumption on the human gut microbiota: a crossover intervention trial. 2025. PubMed 39940045. Read 2026-10-22.
- A review of biogenic amines in fermented foods: occurrence and health effects. 2024. PubMed 38304783. Read 2026-10-22.
- Clemson University Home and Garden Information Center. Food Safety for Pregnant Women and Their Babies. Read 2026-10-22.