# Gut Health Supplements: 8 Ingredients Graded by the Evidence

Source: https://jilllebofsky.com/gut-health-supplements/
By Claire Hadley, Reviews Editor. Updated October 28, 2026. Facts checked October 28, 2026.

**Quick answer:** The gut health supplements with the best human evidence are soluble fiber such as psyllium, enteric-coated peppermint oil for IBS, and specific probiotic strains taken during antibiotics. In children on antibiotics, probiotics cut diarrhea from 19% to 8% across 33 trials. Prebiotics, collagen and bone broth have little support, and people with weak immunity should avoid probiotics unless a doctor advises them.

We ranked gut health supplements by ingredient type and graded each one on human trials. We read two NCCIH fact sheets, the 2020 American Gastroenterological Association (AGA) probiotic guideline, two Cochrane reviews, three meta-analyses or trials on fiber, prebiotics and glutamine, and NIDDK and FDA pages.
The short answer: soluble fiber such as psyllium, enteric-coated peppermint oil for IBS, and specific probiotic strains taken with antibiotics have the best support, while prebiotics, collagen and bone broth have little. In children on antibiotics, probiotics cut diarrhea from 19% to 8% across 33 trials.[5]
Gut health supplements at a glance
What they areFiber, live microbes (probiotics), food for microbes (prebiotics), herbal oils, enzymes and amino acids sold to ease digestive symptoms[1]
Main uses studiedAntibiotic-related diarrhea, IBS symptoms, constipation, lactose intolerance[1][11]
Fiber targetAdults need 22 to 34 grams of fiber a day from food and supplements combined[12]
Best evidenceSoluble fiber for IBS (14 trials), probiotics with antibiotics (31 trials), peppermint oil for IBS (10 studies)[6][4][7]
RegulationFDA does not approve supplements for safety or effectiveness before they are sold[2]
Who should avoid probioticsPeople with severe illness or a weak immune system, and premature infants, unless a doctor directs it[1]

Evidence grades from Cochrane reviews, the AGA 2020 probiotic guideline, NCCIH, NIDDK and published trials.
How did we grade these gut health supplements?
Each ingredient type got one of four evidence grades, based on human trials for gut symptoms. We did not score brands. The grade says how much pooled human research backs a specific use, so one ingredient can rate well for one problem and poorly for another, as probiotics do.[1]

Moderate: several pooled trials show a small, consistent effect.
Limited: some trials, but they are small, few or low quality.
Weak: pilot studies only, reviews found no benefit, or we found no controlled human trials on gut symptoms.
Avoid: no evidence of benefit plus a safety problem for that group.

The table below lists the main studies behind the grades. Our wider method is on the how we review supplements page.
Key studies behind the gradesStudyWho and how manyDose and lengthResult
Moayyedi, 2014 meta-analysis14 trials, 906 adults with IBSFiber supplements vs placeboSoluble fiber helped (1 in 7 improved); bran did not[6]
Goldenberg, 2017 Cochrane31 trials, 8,672 adults and children on antibioticsProbiotics alongside antibioticsC. diff diarrhea 1.5% vs 4.0%, about 60% lower[4]
Guo, 2019 Cochrane33 trials, 6,352 children on antibioticsProbiotics, 5 days to 12 weeks follow-upDiarrhea 8% vs 19%[5]
2022 review cited by NCCIH10 studies, 1,030 people with IBSPeppermint oil capsules vs placeboBetter overall symptoms and less pain, more mild reflux[7]
Wilson, 2019 meta-analysis11 trials, 729 adults with IBS or similarPrebiotics vs placeboNo difference: 54% vs 63% responded[8]
Zhou, 2019 trial106 adults with IBS after a gut infectionGlutamine 5 g three times daily, 8 weeks79.6% vs 5.8% improved; one trial only[9]

1. Psyllium and other soluble fiber: IBS and regularity
Soluble fiber, such as psyllium, is the best-supported daily gut supplement for IBS: grade Moderate. A 2014 meta-analysis of 14 trials with 906 adults found that about 1 in 7 people given soluble fiber improved who would not have on placebo. Wheat bran showed no benefit.[6]
NIDDK lists fiber supplements as an option for IBS with constipation when diet changes are not enough.[10] Adults need 22 to 34 grams of fiber a day, so a supplement only tops up what you eat. Add it a little at a time and drink plenty of liquids so your body adjusts.[12]
Best for: people with IBS or slow, hard stools who eat little fiber. Skip bran-based products if IBS is your reason for buying.
2. Strain-specific probiotics with antibiotics: diarrhea risk
Probiotics taken during a course of antibiotics are the best-studied probiotic use: grade Moderate. A 2017 Cochrane review of 31 trials with 8,672 people found C. difficile diarrhea in 1.5% of the probiotic groups and 4.0% of the control groups, a drop of about 60%.[4]
The benefit was clearest when baseline risk was above 5%: 3.1% vs 11.6%. Overall, 42 people needed to take a probiotic for one to benefit, and 12 in the high-risk trials.[4] In outpatients, a 2017 review of 17 studies (3,631 people) linked probiotics to about half the chance of antibiotic-associated diarrhea.[1]
The AGA's 2020 guideline names specific choices for people on antibiotics: Saccharomyces boulardii, or set combinations such as L. acidophilus CL1285 with L. casei LBC80R.[3] Strain matters, so match the label to those names.
3. Enteric-coated peppermint oil: IBS cramping and pain
Enteric-coated peppermint oil capsules may ease overall IBS symptoms and belly pain: grade Moderate. NCCIH cites a 2022 review of 10 studies with 1,030 people that found peppermint oil beat placebo, though it caused more side effects, mostly mild reflux and indigestion.[7]
The American College of Gastroenterology's 2021 guideline recommends peppermint oil for overall IBS symptoms, and NIDDK lists coated peppermint oil capsules among options for IBS pain.[7][10] The coating helps the oil pass the stomach, which lowers the chance of heartburn.
Best for: adults with diagnosed IBS whose main complaint is cramping. Peppermint oil alone may make indigestion worse, so it is a poor pick for reflux.[7]
4. Lactase enzyme: gas and bloating after dairy
Lactase is the one digestive enzyme with clear official backing, for lactose intolerance only: grade Limited. NIDDK says lactase tablets taken before dairy, or drops added to milk, can help some people manage symptoms by breaking down lactose.[11]
We did not find trials we could read on broad "digestive enzyme" blends for everyday bloating, so they are not graded here. NIDDK also says to check with a doctor first, because young children and pregnant or breastfeeding women may not be able to use lactase products.[11]
Best for: people whose gas, bloating or loose stools follow milk, ice cream or soft cheese.
5. L-glutamine: IBS that started after a gut infection
L-glutamine has one strong-looking trial in a narrow group, which is not enough for a higher grade: Limited. In a 2019 trial, adults with diarrhea-type IBS that began after a gut infection took 5 g three times a day or placebo for 8 weeks.[9]
Of 54 people on glutamine, 79.6% improved by the trial's measure, against 5.8% of 52 on placebo. Side effects were low and similar in both groups. The authors themselves called for larger trials to confirm it.[9]
Best for: people with that specific history, after a doctor has ruled out other causes. The trial says nothing about glutamine for general gut health.
6. Prebiotics (inulin, FOS, GOS): feeding gut bacteria
Prebiotics raised friendly bacteria counts in trials but did not improve symptoms: grade Weak. A 2019 meta-analysis of 11 trials with 729 adults with IBS or similar bowel problems found 54% responded on prebiotics and 63% on placebo, with no real difference.[8]
Inulin-type fructans, common in gut powders, made flatulence worse. Doses of 6 g a day or less did slightly better on gas than larger doses.[8] If a product lists chicory root or inulin and you get bloated, that may be why.
7. Bone broth and collagen: gut lining claims
Bone broth and collagen powders are graded Weak because we found no controlled human trials on gut symptoms. A PubMed search turned up lab and organ studies, not trials in people with digestive complaints. Claims that they "heal" the gut lining have no human trial behind them that we could find.
Collagen powders are sold as supplements, and FDA does not review them for effectiveness before sale, so any gut claim on the label is the maker's own.[2] Broth is fine as food; just do not expect it to settle symptoms.
8. Probiotics if you are seriously ill or immunocompromised: avoid
Probiotics carry real infection risk for some groups, so they are graded Avoid unless a doctor directs their use. NCCIH says harm is more likely in people with severe illness or a weakened immune system, and FDA warned in 2023 about severe, sometimes fatal infections in premature infants given probiotics.[1]
The Cochrane review that supports probiotics with antibiotics limited its safety finding to people who were not immunocompromised or severely weak.[4] If you are on chemotherapy, have a central line, or take drugs that suppress immunity, ask your care team first.
Do probiotics work?
Certain probiotic strains help with certain problems, mainly diarrhea linked to antibiotics. NCCIH notes that a strain that helps one condition does not mean another strain, even of the same group, will do the same.[1] The strongest data are for diarrhea linked to antibiotics in adults and children.[4][5]
For constipation, a 2014 review of 14 studies (1,182 adults) found some benefit, mostly with Bifidobacterium lactis.[1] For IBS, a 2018 review of 53 studies (5,545 people) could not draw firm conclusions or pick the best strains.[1] The AGA goes further: for IBS, Crohn's disease and ulcerative colitis, it recommends probiotics only within clinical trials.[3]
Do probiotics help with bloating, and which probiotic is best for bloating and gas?
No probiotic strain has strong enough evidence to be called the best for bloating and gas. Bloating is a core IBS complaint, and the AGA advises against probiotics for IBS outside research studies because the trials disagree.[3] NIDDK says researchers are still studying them for IBS.[10]
For gas, start by finding the trigger. If dairy is the cause, lactase may help.[11] If you have IBS, soluble fiber and peppermint oil have more pooled trial support than any single probiotic.[6][7] Watch for inulin in probiotic blends, since it worsened flatulence in trials.[8]
Prebiotics vs probiotics: what is the difference?
Probiotics are live microorganisms; prebiotics are fibers that feed microbes already in your gut. NCCIH defines prebiotics as nondigestible food parts that selectively boost helpful microbes, and synbiotics as products that combine the two.[1]
The evidence differs too. Probiotics have moderate-quality support for antibiotic-related diarrhea.[4] Prebiotics increased bifidobacteria in IBS trials, but people did not feel better than on placebo.[8]
How do you check a probiotic label for strain and CFU?
A useful probiotic label names the full strain, the CFU count at the end of shelf life, and the amount per serving. FDA requires a Supplement Facts panel with serving size and the amount of each dietary ingredient, but FDA does not check that the product works before it is sold.[2]
What to check on a probiotic labelLabel itemWhat good looks likeWhy it matters
Genus and speciesSaccharomyces boulardii, Lactobacillus acidophilus, Bifidobacterium lactisDifferent types have different effects[1]
Strain codeLetters and numbers after the species, such as CL1285 or LBC80RAGA advice names exact strains[3]
CFU per dayA stated number in billions; trials in children found 5 billion or more a day worked betterLower doses showed less effect in that review[5]
Count "through expiration"Count promised at the end of shelf life, not at manufactureThe dose you swallow is what counts; ask the maker if unclear
Added prebioticInulin or chicory root listed or absentInulin worsened gas in IBS trials[8]
Disease claimsNone. Words like "treats IBS" are a red flagA product meant to treat a disease is legally a drug[2]

Some probiotic products have been found to contain microbes that were not on the label, so a brand that publishes outside test results is a safer bet.[1]
What should you look for in a greens and probiotic powder?
Treat a greens and probiotic powder as two products in one tub, and check each part on its own. For the probiotic part, use the label table above: named strain, CFU per serving, and whether that strain matches a studied use.[3] We found no trials of blended greens powders for gut symptoms.
Look for a "proprietary blend" that hides amounts, since you cannot compare it to any trial dose. Check for inulin or chicory, which can add gas.[8] Count the fiber per scoop against the 22 to 34 grams adults need daily.[12]
What are the signs probiotics are working?
The only reliable sign is that the specific symptom you bought it for gets better, compared with a written baseline. Note stool frequency, pain and bloating for a week before you start, then keep the same notes while you take it.
NIDDK says people with IBS may have to try a few treatments to find what works, ideally with a doctor.[10] If nothing changes, stop and talk to your doctor before trying another product. NCCIH warns not to let probiotics delay a visit to your health care provider.[1]
Which gut health supplement fits your situation?
Match the ingredient to the problem, because each one was tested for a different symptom. Use this decision table as a starting point for a talk with your doctor or pharmacist.
If this is your situation, consider this firstIf you haveConsider firstGrade
Diagnosed IBS, mostly crampingEnteric-coated peppermint oil[7]Moderate
IBS with constipation, low fiber intakePsyllium or another soluble fiber[6]Moderate
A course of antibiotics coming upS. boulardii or an AGA-named strain mix[3]Moderate
Gas or bloating after dairyLactase tablets or drops[11]Limited
IBS with diarrhea that began after a stomach bugAsk about L-glutamine[9]Limited
Weak immune system or serious illnessNo probiotic unless your doctor says so[1]Avoid

Who should avoid probiotics and other gut supplements?
People with weakened immunity, severe illness, or premature babies should not use probiotics without a doctor's direction. Possible harms include infections, harmful substances made by the microbes, and transfer of antibiotic resistance genes.[1] Probiotics are also not advised for children with acute infectious gastroenteritis.[3]
Peppermint oil can cause heartburn, nausea and dry mouth, and should never be applied to an infant's face.[7] Lactase may not suit young children or pregnant or breastfeeding women.[11] Adding fiber too fast can cause gas and cramps, so go slowly.[12] If you take medicines, ask a pharmacist, because supplements can interact with drugs.[2]
See a doctor promptly if gut symptoms are new, severe or getting worse. NCCIH advises against using probiotics as a reason to put off that visit.[1]
What do doctors use first for gut problems?
For IBS, doctors usually start with diet and lifestyle changes, then medicines and talk therapies, with supplements as add-ons. NIDDK lists more fiber, avoiding gluten, or a low FODMAP eating plan, along with more activity, less stress and better sleep.[10]
Prescription options include loperamide or rifaximin for diarrhea-type IBS, and linaclotide or lubiprostone for constipation-type IBS. Cognitive behavioral therapy and gut-directed hypnotherapy also have a place.[10] For lactose intolerance, the first step is cutting back on lactose.[11] More digestion guides are in our probiotics and digestion section.
Practical checklist before you buy

Write down the one symptom you want to change and track it for a week first.
Match the ingredient to that symptom using the decision table above.
For probiotics, find the full strain name and the CFU count through expiration.
Skip proprietary blends that hide amounts per ingredient.
Check for inulin or chicory root if gas is already a problem.[8]
Choose enteric-coated capsules for peppermint oil.[7]
Ignore any label that says it treats or cures a disease.[2]
Read how we pick sources in our editorial policy.

Bottom line
Most gut health supplements on the shelf have thin evidence, but three ingredient types hold up: soluble fiber, enteric-coated peppermint oil for IBS, and named probiotic strains taken with antibiotics.[6][7][4] Prebiotics, collagen and bone broth sit at the bottom.[8]
For most people, a slow increase in fiber is the better first step than a probiotic, because it is cheap, NIDDK recommends it, and soluble fiber has pooled trial support for IBS.[12][6] Save probiotics for a specific reason, such as an antibiotic course, and check with a doctor if your immune system is weak.

## Frequently asked questions

### Do probiotics work?

Some strains work for some uses. The best evidence is for diarrhea linked to antibiotics, where Cochrane reviews found fewer cases with probiotics. For IBS, reviews could not name a reliable strain, and the AGA advises probiotics for IBS only within clinical trials.

### Are daily gut health supplements necessary?

Most people do not need one. Adults should get 22 to 34 grams of fiber a day, mostly from food. A fiber supplement can fill a gap. Other products make sense only for a specific problem, such as an upcoming antibiotic course or diagnosed IBS.

### Are probiotics FDA approved?

No. Probiotics sold as dietary supplements do not need FDA approval before they are marketed. FDA cannot approve supplements for safety or effectiveness before sale, and a product that claims to treat a disease is legally a drug.

### Can I take a probiotic and a fiber supplement together?

Many people do, and they serve different roles: fiber adds bulk, while a probiotic adds live microbes. Add fiber slowly with plenty of fluids to limit gas. If you have a weak immune system, ask your doctor before starting any probiotic.

### How many CFU should a probiotic have?

There is no single right number. In children on antibiotics, a Cochrane review found doses of 5 billion CFU or more a day worked better than lower doses. For other uses, match the strain and dose to the trial behind that use.

## Sources

1. [Probiotics: Usefulness and Safety](https://www.nccih.nih.gov/health/probiotics-usefulness-and-safety). NCCIH, current
2. [FDA 101: Dietary Supplements](https://www.fda.gov/consumers/consumer-updates/fda-101-dietary-supplements). U.S. Food and Drug Administration, current
3. [AGA Clinical Practice Guidelines on the Role of Probiotics in the Management of Gastrointestinal Disorders](https://gastro.org/clinical-guidance/role-of-probiotics-in-the-management-of-gastrointestinal-disorders/). American Gastroenterological Association, 2020
4. [Probiotics for the prevention of Clostridium difficile-associated diarrhea in adults and children (Goldenberg et al.)](https://pubmed.ncbi.nlm.nih.gov/29257353/). Cochrane Database of Systematic Reviews, 2017
5. [Probiotics for the prevention of pediatric antibiotic-associated diarrhea (Guo et al.)](https://pubmed.ncbi.nlm.nih.gov/31039287/). Cochrane Database of Systematic Reviews, 2019
6. [The effect of fiber supplementation on irritable bowel syndrome: a systematic review and meta-analysis (Moayyedi et al.)](https://pubmed.ncbi.nlm.nih.gov/25070054/). American Journal of Gastroenterology, 2014
7. [Peppermint Oil: Usefulness and Safety](https://www.nccih.nih.gov/health/peppermint-oil). NCCIH, current
8. [Prebiotics in irritable bowel syndrome and other functional bowel disorders in adults (Wilson et al.)](https://pubmed.ncbi.nlm.nih.gov/30949662/). American Journal of Clinical Nutrition, 2019
9. [Randomised placebo-controlled trial of dietary glutamine supplements for postinfectious irritable bowel syndrome (Zhou et al.)](https://pmc.ncbi.nlm.nih.gov/articles/PMC9549483/). Gut, 2019
10. [Treatment for Irritable Bowel Syndrome](https://www.niddk.nih.gov/health-information/digestive-diseases/irritable-bowel-syndrome/treatment). NIDDK, reviewed 2017
11. [Treatment for Lactose Intolerance](https://www.niddk.nih.gov/health-information/digestive-diseases/lactose-intolerance/treatment). NIDDK, reviewed 2018
12. [Eating, Diet, and Nutrition for Constipation](https://www.niddk.nih.gov/health-information/digestive-diseases/constipation/eating-diet-nutrition). NIDDK, current

General information from JillLebofsky, not medical advice.