IBS and Medicinal Mushrooms: What Was Measured, What Actually Helps, and What About Imodium

In brief5 points · 1-minute read

• Reishi, lion's mane, cordyceps and turkey tail have never been tested in an IBS trial, and no such trial is registered on ClinicalTrials.gov.
• Peppermint oil, psyllium, low-dose amitriptyline in 463 patients and the low-FODMAP diet are what the evidence supports; we sell none of them.
• Polyols triggered symptoms in 20 IBS patients but not 21 healthy controls in a Monash trial, and 19 of 64 subjects reacted to 25 grams of trehalose.
• Loperamide is cleared by CYP3A4, an enzyme reishi inhibited in rat microsomes; the combination was never measured in humans, so ask a pharmacist.
• The mannitol and trehalose content of our extracts was not measured, so this page never calls them low-FODMAP, and never calls mushrooms forbidden either.

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In irritable bowel syndrome (IBS), “natural treatment” is the first Google autocomplete — and the medicinal mushrooms offered for it are lion’s mane (Hericium erinaceus), reishi (Ganoderma lucidum, the lingzhi of Chinese medicine), turkey tail and cordyceps. The honest answer: no human trial in IBS has tested a medicinal mushroom — none completed, none registered. What was measured — peppermint oil, psyllium, low-dose amitriptyline, low-FODMAP — we do not sell. Whether mushrooms suit an irritable bowel — here.

The kinds of evidence that do exist, from closest to a person to furthest away: network meta-analyses of thousands of patients on the drugs and diets we do not sell; a randomized human trial in which a food of the polyol family — the family mushrooms belong to — triggered symptoms specifically in IBS patients; a loading test of the mushroom sugar in 64 subjects; a retrospective analysis of a five-ingredient blend, sponsored by its manufacturer, with no control group; microbiome trials in healthy volunteers that measured not one symptom; a double-blind trial from 1985 on lion’s mane in the stomach, which has no abstract; and one mouse study on a compound from reishi, whose effect vanished when antibiotics were given. On “mushroom × IBS in humans” — there is nothing at all. This page is written around what you actually ask, and it starts from what does work.

Do medicinal mushrooms help with IBS — what was actually tested?

Nothing — in humans. Not one trial, randomized or pilot, has tested reishi, lion’s mane, cordyceps or turkey tail in people with irritable bowel syndrome; and the ClinicalTrials.gov registry holds none either — the search returns a single trial, on barley beta-glucan. What exists is one mouse study, one uncontrolled blend, and the microbiome of healthy volunteers.

To understand how unusual that is, it helps to know the scale. In the Rome Foundation Global Study — 73,076 respondents in 33 countries, led by a researcher from Ben-Gurion University — 40.3% of internet-survey respondents met the criteria for at least one disorder of gut-brain interaction; IBS by Rome IV definitions was found in 4.1% in the internet survey and 1.5% in the household survey, and by the broader Rome III definitions — 10.1% and 3.5%. Women are at higher risk. This is a condition that touches millions, with an entire supplement market — and nobody has tested a mushroom in it. Not because they tested and found zero: they simply did not test.

And so this page does not start from the mushrooms. It starts from what was measured and works, moves on to what you actually ask — whether mushrooms suit IBS at all, whether they are low-FODMAP, whether they can be combined with Imodium or mebeverine — and only then reaches what the market sells. That order is deliberate: when a seller of mushroom extracts first tells you what works among the things he does not sell, there is reason to believe him on the rest.

What was measured, in which system — and what came out?

The table sorts your questions by what was measured, and in which organism. Four mushroom rows hold mice, a blend and healthy volunteers — not IBS patients. Only the drug and diet rows, which we do not sell, have meta-analyses. One row — can mushrooms make it worse — is the only human measurement pointing where the market does not.

What actually helps IBS according to the research — and which of it do we not sell?

All of it. In a network meta-analysis of 51 randomized trials in 4,644 patients, peppermint oil and low-dose amitriptyline ranked first for symptom relief (RR 0.63 and 0.66 for treatment failure); psyllium is the only fiber that works (RR 1.53 for response); the low-FODMAP diet is the only one that reduced bloating (RR 0.55). We sell none of them.

Peppermint oil. Two meta-analyses on roughly the same trials, two conclusions: the 2022 update from Ford’s group — 10 trials, 1,030 patients, NNT 4 for global improvement, but “more adverse events” (RR 1.57) and “very low” quality of evidence; and a 2019 meta-analysis from Johns Hopkins — 12 trials, 835 patients, global improvement RR 2.39, adverse events 9.3% versus 6.1% and not significant, NNT 3. The foundation is from 2008 in the BMJ: 4 peppermint trials in 392 patients, RR 0.43 for persistent symptoms. Antispasmodics. In the same 2008 work — 22 trials in 1,778 patients, RR 0.68; consistent for otilonium (0.55) and hyoscine (0.63). Fiber. Only the soluble kind: psyllium RR 0.78 in 2008; in a 2014 meta-analysis (14 trials, 906) soluble fiber NNT 7, and bran “neither helps nor harms”; and in the 2026 update in Gastroenterology (30 trials, 1,904 patients) — clinical response 52% versus 44%, and psyllium RR 1.53. Low-dose amitriptyline. The largest trial in the world, ATLANTIS, in the Lancet in 2023: 463 patients across 55 primary-care practices in England, 10 mg titrated up to 30 mg, 6 months — the IBS-SSS severity score fell 27.0 points more than on placebo (p=0.0079); “safe and well tolerated”. This is a “low-dose gut-brain neuromodulator”, not a treatment for depression — the depression dose is far higher. Diet. A 2025 network meta-analysis of 28 trials in 2,338 patients: low-FODMAP RR 0.51 for global improvement (24 trials), RR 0.61 for pain, and the only diet that reduced bloating against a regular diet; no diet changed bowel habit. Probiotics. 82 trials, 10,332 patients, and only 24 at low risk of bias: moderate certainty for Escherichia strains only; for everything else — “low to very low”. Anyone typing “IBS probiotics” should hear that before buying — a probiotic without a strain name is a word, not a treatment.

Those are the numbers. We do not recommend a drug and we do not set a dose — that belongs to the physician; we write them because they are what was measured, and because they are the bar every other supplement has to be measured against. Medicinal mushrooms were never measured against it at all.

Is there research on reishi in IBS?

One — in mice, from 2026. Ganoderic acid A, a triterpene isolated from reishi, was given to mice with an IBS-like state induced by bacterial infection and stress; it improved motility, reduced visceral sensitivity and strengthened the gut barrier — and antibiotics abolished the benefit entirely. Humans with IBS: 0 studies. Human colitis: 0. Human microbiome, randomized: 0.

What the market claims. “Reishi calms the nervous system and IBS is gut-brain”, “reishi is anti-inflammatory”, “reishi balances the microbiome”. Three claims, and not one of them measured in a person with IBS.

What exactly was measured. The only study in the world in which “reishi” and “irritable bowel syndrome” appear in the same record: C57BL/6 mice, infection with Citrobacter rodentium plus water-avoidance stress, and then ganoderic acid A — not a reishi extract, one compound from within it. The result: restored motility, regulation of enteric neurons, less visceral hypersensitivity, less colonic inflammation, a stronger epithelial barrier. The mechanism the authors propose: microbiome remodeling → tryptophan-metabolizing bacteria → indole-3-aldehyde → the AhR receptor. And the decisive sentence: antibiotic treatment completely abolished the benefit — meaning the effect depends on the mouse’s gut bacteria. Dose and number of mice are not stated in the abstract, and so they are not stated here.

Why it does not carry over to a person. A mouse with an induced infection and stress is not a person with IBS; an isolated compound is not an extract; and the microbiome of a laboratory mouse is not yours. And beyond that — the next step, a human trial, was not done: not in IBS, not in colitis, and not even one randomized trial on the effect of reishi on the human microbiome (the search returns three records — a protocol, and reviews — and no trial). What was measured on reishi in humans and the digestive system: constipation in 4% and nausea — in the chapter on side effects. What to ask the doctor. Not “does reishi help” — but “which of my drugs go through CYP3A4”, because that is the only enzyme where reishi-in-a-dish and an IBS drug meet (the chapter on drugs).

Does lion’s mane help with IBS?

Not measured — not in humans, and not even in an animal IBS model. The only record is a 2024 retrospective analysis of 123 patients who received a blend of probiotics, lion’s mane, PEA and seaweed for one month, with no control group and no lion’s-mane-only arm — and three of the authors work for the manufacturer.

This is the mushroom of the English search — “lions mane ibs” returns ten autocompletes — so let us go through what exists, up close. The 2024 analysis: 123 IBS patients, one capsule a day of a commercial preparation, 4 weeks. The Bristol scale rose in constipation from 1.5 to 3.3 and fell in diarrhea from 6.5 to 4.3; pain on a VAS scale fell from 6.7 to 2.8 (p<0.001). The numbers look impressive, which is why it matters to say what is missing: no control group, no placebo, no arm that received lion’s mane alone — and the authors themselves write that “controlled trials are needed”. In IBS, control groups respond at high rates: in the 2020 network meta-analysis, 44% of patients in the control arms of the fiber trials responded. A before/after analysis with no control cannot separate the mushroom, the probiotics, the PEA and time. The same company published a similar analysis in 2026 in 54 patients with diverticulosis — not IBS — with the same limitation.

Beyond that — nothing. A search for lion’s mane with IBS, visceral sensitivity, functional dyspepsia or functional bowel disorders returns that record alone; an animal IBS model with lion’s mane — 0. The only human evidence on lion’s mane and the digestive system is a 2021 pilot in 13 healthy adults who took a powder for 7 days, without a control: bacterial diversity rose, and no symptom was measured. And what was measured in humans on lion’s mane and the digestive system goes the other way: in a 49-week trial, four subjects dropped out because of abdominal discomfort, nausea and rash. “Lion’s mane for IBS” is a marketing sentence with not a single measurement behind it — neither for nor against. If lion’s mane interests you for concentration rather than for the gut — the lion’s mane and brain fog page lays out what was measured there.

“Lion’s mane is good for the stomach” — what does that mean for someone with IBS?

Nothing. The stomach and the irritable bowel are two organs and two conditions. The evidence on lion’s mane and the stomach: a 1985 double-blind trial in chronic atrophic gastritis with no PubMed abstract and no quotable number; ethanol ulcers in rats; and H. pylori in a dish. Reviews from 2023 and 2025 call this “preliminary evidence” and ask for more.

The claim “lion’s mane is good for digestion” was born in the stomach, and from there it leaked into the bowel. The source of the claim is a Chinese trial from 1985 — “A double-blind study of effectiveness of hericium erinaceus therapy on chronic atrophic gastritis, a preliminary report” — of which all that remains on PubMed is the title and the methodology classification: number of participants, dose and outcome are not available, and so they are not written here. Even after 40 years, that is what there is: a 2023 review in the World Journal of Gastroenterology writes of “therapeutic potential” in gastritis, and a 2025 letter from the same group sums up “preliminary clinical data” and adds explicitly that “further evidence is needed before proposing the mushroom as a complementary approach”. In rats, an aqueous extract shrank an ethanol-induced stomach ulcer and preserved protective enzymes; in a dish, extracts and isolated compounds from lion’s mane inhibited H. pylori at concentrations of 6.25 to 400 micrograms per milliliter. An ulcer in a rat and a bacterium on a plate are not IBS — a condition of the large bowel and the gut-brain axis, with no ulcer and no bacterium. Whoever carries “good for the stomach” over to “good for IBS” is moving a finding between two organs without asking whether anyone measured.

Turkey tail and cordyceps — is there anything at all?

Zero, for both. Cordyceps with IBS or visceral sensitivity — 0 records, not even in animals; and “does cordyceps cause diarrhea” — not measured: 7 human cordyceps trials reported adverse effects, and none measured digestive symptoms as an outcome. Turkey tail with IBS — 0; what exists is one randomized trial on the microbiome of 24 healthy volunteers.

Turkey tail. The only randomized trial in the world of turkey tail on the human microbiome, from 2014: 24 healthy volunteers were assigned to PSP (the polysaccharopeptide from the mushroom), to amoxicillin or to an untreated control; 22 completed 8 weeks with 7 stool samples. PSP “led to clear and consistent microbiome changes, consistent with prebiotic activity” — and in the same abstract: “baseline microbiomes tended to remain stable and overshadow treatment effects”. The dose was not stated, and no symptom was measured. In a dish, on human stool, a turkey tail extract raised Bifidobacterium and Lactobacillus and lowered Clostridium. That is the whole file — and what we do say about turkey tail and the gut we wrote on the “is turkey tail good for the gut” page. In Hebrew, incidentally, “turkey tail for” returns zero autocompletes — nobody is asking yet.

Cordyceps. A search for cordyceps with IBS, visceral sensitivity or visceral pain — 0 records, in any organism. In English people ask “does cordyceps cause diarrhea” and “does cordyceps cause constipation”; a search for randomized human trials of cordyceps with diarrhea, the digestive system or adverse effects returns 7 records — meta-analyses in lung cancer, in dialysis and in kidney transplantation — and not one of them measured digestive symptoms as an outcome. The answer to the question is “not measured”, not “no”. In the 2023 safety database of 1,816 adverse-event reports, cordyceps appears in one report — upper gastrointestinal bleeding together with sertraline — which we detailed on the cordyceps safety page.

Mushrooms and “balancing the microbiome” — what was measured in humans?

Changes in bacterial composition — in healthy volunteers, with no symptom measured. Turkey tail in 24 healthy adults, shiitake in 52 with high cholesterol, button mushrooms in 32, lion’s mane in 13 for 7 days. A change in stool composition is a marker, not an outcome; and in the button-mushroom trial mushrooms caused more digestive symptoms in the first days.

“They balance the microbiome” is the claim that connects mushrooms to IBS on every sales page, so let us check what stands behind it in humans. Turkey tail: the 2014 RCT described above — changes that were “clear and consistent”, which the baseline “overshadowed”. Shiitake: 52 adults with high cholesterol received 10.4 grams a day of a beta-glucan-enriched blend (3.5 grams of beta-glucans) or placebo, 8 weeks, double-blind — the microbiome changed differently from placebo, and zero change in lipids, in cytokines and in oxLDL; “consumption was safe”. Lion’s mane: 13 healthy adults, 7 days, no control — alpha diversity rose; “a physiological adaptation to 7 days of supplementation”. Button mushrooms: 32 healthy adults, crossover trial, mushrooms or meat twice a day for 10 days — more Bacteroidetes, fewer Firmicutes, higher stool weight with undigested mushrooms in the stool, and “the mushroom diet led to more overall digestive symptoms on days 1 and 2”. In a dish, on human stool, lion’s mane beta-glucan raised butyrate. And in an ex vivo system with the stool of 8 IBS patients — a commercial laboratory, no patient took anything — a mushroom blend raised propionate, and triacetin raised butyrate “with less gas production than the blend”; the authors note that “fibers generally increase gas production and may worsen IBS symptoms”.

The honest summary: in humans, mushrooms change the composition of the bacteria in the stool — like any fiber. Nobody has measured whether that change eases an IBS symptom, and the one consequence that was measured — fermentation, gas, symptoms in the first days — is the direction an irritable bowel does not need. The broader background on mushrooms and gut health and on mushrooms and the digestive system we wrote separately.

Are mushrooms low-FODMAP — and can lion’s mane cause diarrhea or bloating?

Three measured facts, one honest answer. Polyols — mannitol and sorbitol, in “certain vegetables” — triggered symptoms in 20 IBS patients and not in 21 healthy controls, independently of absorption. 19 of 64 subjects did not tolerate a 25 gram trehalose load, the mushroom sugar. A measured FODMAP value for lion’s mane: not published on PubMed, nor for our extract.

This is the door through which people reach this page in English — “is lion’s mane low fodmap”, “can lion’s mane give you diarrhea”, “why are mushrooms bad for ibs” — and no sales site answers it, because the answer does not sell. Polyols. The 2014 Monash trial, randomized double-blind placebo-controlled: 21 healthy controls and 20 IBS patients received challenges of 10 grams of sorbitol, mannitol or glucose. Mannitol absorption was actually better in the IBS patients (80% versus 43%, p=0.02) — and yet symptoms rose significantly after both polyols in IBS patients only, and independently of malabsorption. The authors’ conclusion: restricting polyols “may be effective”. The abstract writes that mannitol is “higher in certain vegetables”; the word “mushrooms” is not in it, and Monash’s values for mushrooms are not indexed on PubMed — they exist in the app only, so we will not quote a number from them. Trehalose. The mushroom sugar, which is not part of FODMAP: in 1999, 64 subjects received an oral load of 25 grams of trehalose, and 19 of them experienced “clear symptoms”; in 2 a deficiency of the enzyme trehalase was found. The mechanism the authors describe: low enzyme → trehalose reaches the colon → draws water (diarrhea) → gas if the bacteria ferment it; “trehalose maldigestion can cause symptoms similar to lactose intolerance”. And lion’s mane is full of it: a 2023 NMR analysis of four mushrooms found that “trehalose was the dominant carbohydrate in most samples”, alongside sugar alcohols — in fruiting body and mycelium alike; the quantitative values are not in the abstract. And on the plate. The 2018 button-mushroom trial — more digestive symptoms in 32 healthy adults on days 1–2.

And what about the extract? Here we will say what nobody says: an extract is not a whole mushroom — extraction in hot water and alcohol changes the profile of the small sugars — but we have no measurement of the mannitol or trehalose content of our extracts, and so we will not write “FODMAP-free”. What can be said: “not measured; whole mushrooms contain polyols and trehalose; in some people with IBS they trigger symptoms; whoever tries — starts with a small dose and listens to the gut”. “Mushrooms are forbidden in IBS” is the other side of the same trap: 19 of 64 did not tolerate a large dose of trehalose, and 45 did; the button-mushroom symptoms were on days 1–2 only. “Can worsen in some” — not “forbidden”, and not “safe”.

What digestive side effects were reported in trials of reishi and lion’s mane?

They exist, unquantified. Lion’s mane: in a 49-week trial of enriched mycelium, four subjects dropped out over abdominal discomfort, nausea and rash; short trials reported “no adverse effect”, with digestive symptoms not listed separately. Reishi: a 1,374-user survey — constipation 4%, dry mouth 5%; Cochrane — nausea; a meta-analysis — RR 1.67 for any adverse effect, not significant.

For anyone whose gut is already sensitive, this is the practical chapter. Lion’s mane. The only figure with a number: a 49-week double-blind trial in mild Alzheimer’s disease, 3 capsules of 350 mg erinacine A-enriched mycelium a day — “except for four subjects who dropped out because of abdominal discomfort, nausea and skin rash, no other adverse effects were reported”; the total number of participants was not stated, so there is no percentage; the manufacturer, Grape King Bio, is the first author; and it is mycelium, not fruiting body. In 30 adults with mild cognitive impairment, 3 grams a day for 16 weeks — “laboratory tests showed no adverse effect”, with no separate report on digestion. In 41 young adults — “limited null and negative findings were also observed”, without detail. In 30 women who ate lion’s mane cookies, in 77 people with overweight and in a 12-week cognition trial — adverse effects were not reported in the abstract at all. A search for human lion’s mane trials that write “gastrointestinal” in the abstract in a safety context — 2 records. In other words: there is a signal (dropouts over the gut and nausea), and there is no denominator. Reishi. A 2024 survey of 1,374 cancer patients: 9.1% reported an adverse effect — dry mouth 5%, constipation 4%, insomnia 3%, itching 3%, vertigo 3% — and on the other side 55% reported that “nausea improved”; self-report, no control. The 2016 Cochrane review: one study recorded “nausea and insomnia” as minimal adverse effects. The 2015 Cochrane review: a risk ratio of 1.67 for any adverse effect after 4 months, a confidence interval crossing 1, “no serious effects”. Anyone who starts a supplement and whose gut reacts — that is a measurement on themselves worth more than all the literature; stop, and tell the doctor. The broader list we gathered on the who shouldn’t take lion’s mane and who shouldn’t take reishi pages.

Taking Imodium, mebeverine, amitriptyline or linaclotide — what is known about combining them with mushrooms?

No study has tested a mushroom with any IBS drug — 5 search results, 0 relevant. Loperamide (Imodium) is broken down in human microsomes by CYP3A4 and CYP2C8, and reishi inhibited CYP3A in rat microsomes — theory, not measurement. Mebeverine (Colofac) is cleared by esterases, linaclotide is barely absorbed, amitriptyline runs through CYP2D6 and CYP2C19 — no shared enzyme.

Imodium (loperamide). In 2004, in human liver microsomes, the breakdown of loperamide was catalyzed by CYP2B6, 2C8, 2D6 and 3A4; ketoconazole, a CYP3A4 inhibitor, inhibited it by 90%, and quercetin, a CYP2C8 inhibitor, by 40%. The authors: “co-administration of these P450 inhibitors may cause interactions — the clinical significance requires study”. Reishi, in 2007, inhibited CYP1A2, CYP3A and CYP2E1 in rat microsomes; and in mice, a reishi triterpene extract lowered the expression of CYP1A2 and CYP3A4 in the colon tissue itself — meaning the CYP axis exists in the gut too, not only in the liver. This is the only theoretical link on the page, and all it is: an enzyme reishi blocked in a dish also breaks down loperamide. In humans — 0 measurements. The wording we can stand behind: the enzyme that breaks down Imodium was inhibited in the test tube by reishi; in humans that was not measured — a question for the pharmacist. Not “reishi raises Imodium levels”. And incidentally, the only place on PubMed where reishi and loperamide meet is a constipation model in mice — where loperamide is the toxin that creates the model, not a co-administered drug.

Mebeverine (Colofac). Rapidly broken down by blood esterases to mebeverine alcohol and veratric acid — not by cytochrome enzymes. Reishi was not tested against esterases; there is no theoretical link, and no measurement. Linaclotide (Linzess). A peptide that is barely absorbed: stable in the stomach, converted in the small intestine to an active metabolite, with 3–5% of the dose excreted as active peptide in the stool — low systemic exposure, no liver and no CYP. Low-dose amitriptyline (Elavil). According to the 2016 CPIC guideline, it is affected by CYP2D6 and CYP2C19 genotype — not the enzymes reishi inhibited in the dish; no direct theoretical link, and no study. In the 2023 safety database, the case with amitriptyline (delirium) was with another plant, not a mushroom. Otilonium, hyoscine, peppermint oil, rifaximin — 0 studies with mushrooms, and we did not gather their metabolic pathways, so we will write nothing about them. The common line: “not tested” for every drug; a theoretical link for one (Imodium); and anyone on a regular medication tells the doctor or pharmacist about every supplement. The wider picture we gathered on the drug interactions page, and exactly the same axis — amitriptyline, CYP, and what reishi did in the dish — on the fibromyalgia page.

IBS and anxiety — and where are the mushrooms in this?

“IBS anxiety” is the fourth Google autocomplete in Hebrew, and it makes sense: IBS is defined as a disorder of gut-brain interaction, and the second-ranked drug for it is a neuromodulator. But there is not one trial — of reishi or of lion’s mane — in which anxiety was the primary endpoint, and none was done in people with IBS.

What was measured on the mushrooms and mood, and why it does not reach here: 30 women who ate lion’s mane cookies for 4 weeks — depression and anxiety scores fell from baseline, and against placebo significance was reached on two questionnaire items only; 77 people with overweight and depression, anxiety or sleep disorders, 8 weeks of lion’s mane on a diet — depression, anxiety and sleep improved, but with no placebo arm in the abstract; 41 young adults, 28 days — a drop in subjective stress that reached p=0.051, not significant. On reishi and anxiety — a placebo-controlled trial in which anxiety is the primary measure does not exist, and everything that does exist we detailed on the reishi for stress and anxiety page. The link between the gut and the head is real and is treated — low-dose amitriptyline in 463 patients is the example — but a mushroom tested on mood in another population is not an IBS treatment, and was never tested as one.

What to eat and what not to — do mushrooms belong on an IBS plate, and what about “home remedies”?

The only diet with moderate-certainty evidence is low-FODMAP: RR 0.51 for overall improvement in 24 trials, and the only one that reduced bloating. Mushrooms contain polyols and trehalose, and in some patients they trigger symptoms — so low-FODMAP handles them with care. Of the “home remedies”, one was seriously tested: peppermint oil, 10 trials, NNT 4. Mushrooms — not tested.

“What to eat” and “what not to eat” are two strong searches in Hebrew, and “grandma’s remedies” is the third. On the plate, the 2025 network meta-analysis tested 11 diets in 28 trials: a starch- and sucrose-reduced diet ranked first (RR 0.41) on the basis of only two trials; low-FODMAP fourth (RR 0.51) on the basis of 24 trials, with moderate certainty against a regular diet — the strongest evidence in the field — and it is the only one that reduced bloating (RR 0.55); the British guideline diet (BDA/NICE) tenth. No diet changed bowel habit. And where do mushrooms fit in? As a food with polyols and trehalose — the FODMAP chapter answers: it was measured, and some people react; start with a small amount, and if a pattern shows in the diary — that is a matter for the dietitian or the gastroenterologist, not for a page. Of the “home remedies”, the one that passed the test of trials is peppermint oil: RR 0.43 for persistent symptoms in 2008, NNT 4 in 2022, with the caveat “more adverse events” in one of the meta-analyses. Medicinal mushrooms did not pass that test — because nobody ever submitted them to it.

What we actually measure in our bottle

After a whole page of “not measured”, you deserve to know what was measured — and about what exactly. We grow the mushrooms ourselves, on a farm in the Galilee: fresh fruiting body, not mycelium grown on grain — like the one in the 49-week trial you read about above — and not imported powder whose name on the sack cannot be verified. The mushroom goes from harvest straight to extraction, with no drying step in between; as far as we know, we are among the few in the world who work this way. The extraction is triple, and its alcohol stage runs for 7 weeks. Extraction ratios on a fresh-mushroom basis: lion’s mane 1:2, reishi 1:3 and turkey tail with reishi 1:3. Alcohol in the finished extract: 32%.

And the numbers are not ours to set. We sent the finished extracts for testing at TÜV Austria, and what came back is the beta-glucan percentage on a dry-matter basis — and alongside it alpha-glucan, meaning starch, which was not detected in any of them. Alpha-glucan not detected is the chemical proof that there is no grain in the bottle. To understand why that matters, it helps to know the market’s three-step ladder: mycelium grown on grain, where beta-glucan is usually below 7% and most of the weight is the grain’s starch; imported dried fruiting body, whose quality depends on who dried it and when; and fresh fruiting body from the farm, which is what we do. And on a page about IBS we also have to say what we did not measure: the mannitol and trehalose content of the extracts — we have no figure, and so we will not write “low-FODMAP”. Why beta-glucan and not “total polysaccharides” — we explained separately.

All our tests are public, and anyone who wants to read the report themselves will find our explanation of how to read a COA. Kosher certification — Mateh Yehuda Rabbinate, Rabbi Gad Atias. That is what we know how to measure and prove about what is in the bottle. What it will do for your irritable bowel was not measured — so it is not written.

What this page does not say — and what we do not claim

We do not claim that reishi, lion’s mane, turkey tail or cordyceps ease IBS, reduce abdominal pain, bloating, diarrhea or constipation, or “balance the microbiome” in a way that changes a symptom — at any dose and in any form; none of them has been tested in humans with IBS. We do not claim that our extracts are “low-FODMAP” — we did not measure. We do not claim the opposite either — that mushrooms are forbidden in IBS: the evidence is that polyols and trehalose trigger symptoms in some people, not in everyone. We do not claim that reishi raises Imodium levels in the blood — that was not measured; and we do not claim the combination is safe — that was not measured either. We do not claim that “probiotics help” — the certainty is low for almost every strain. And we do not deal here with disability benefits, insurance or diagnosis — IBS is diagnosed by a physician after other conditions have been ruled out, and we have no expertise in that. What we do say: IBS is managed by a family physician or a gastroenterologist, with a dietitian when needed; anyone taking Imodium, mebeverine, amitriptyline, linaclotide or any regular medication — talks to the doctor or pharmacist before any supplement, including ours. Under DSHEA, a dietary supplement may not claim to diagnose, treat, cure or prevent any disease. We sell mushroom extracts, and we are telling you explicitly not to buy them for IBS.

The bottom line

Medicinal mushrooms have not been tested in humans with IBS — not in a trial and not in a registry. What exists: one mouse, one blend with no control, and the microbiome of healthy people. What was measured and works — peppermint oil, psyllium, low-dose amitriptyline, low-FODMAP — we do not sell. What was measured on mushrooms and IBS goes in the opposite direction: polyols and trehalose trigger symptoms in some patients, and their content in our extract was not measured. On Imodium: a theoretical link through CYP3A4, zero measurement — a question for the pharmacist. And if someone sells you a mushroom “for IBS” — send them this page, and go to a gastroenterologist.

Frequently asked questions

Does lion’s mane help with IBS?

Not measured — not in humans and not even in animals. The only record is a 2024 retrospective analysis of 123 patients who received a blend of probiotics, lion’s mane, PEA and seaweed, with no control group and no lion’s-mane-only arm, and three of the authors work for the manufacturer. Nothing in the result can be attributed to the mushroom. A trial of lion’s mane alone in IBS: 0.

Is lion’s mane low-FODMAP?

No measured value has been published on PubMed, and none for our extract. What is known: mushrooms contain polyols (mannitol) and trehalose, the mushroom sugar; in the Monash RCT polyols triggered symptoms in IBS patients and not in healthy controls; and 19 of 64 subjects did not tolerate a 25 gram load of trehalose. An extract is not a whole mushroom — but we did not measure, so we will not write “FODMAP-free”.

Can lion’s mane cause diarrhea or stomach pain?

In some people — probably yes, and without a number. In a 49-week trial four subjects dropped out because of abdominal discomfort, nausea and rash; the denominator was not stated. Shorter trials did not report digestive symptoms separately. And the general mechanism exists: undigested trehalose draws water into the colon. If your gut reacts — stop, and tell the doctor.

Can I take reishi with Imodium?

Not measured — a question for the pharmacist. What is known: loperamide is broken down in human microsomes by CYP3A4 (ketoconazole inhibited it by 90%) and CYP2C8; reishi inhibited CYP3A in rat liver microsomes. That is a theoretical link between one enzyme and another, not a measurement of the combination in a person. Studies of a mushroom with loperamide in humans: 0.

And with mebeverine (Colofac) or amitriptyline?

Not tested — and there is not even a theoretical link. Mebeverine (Colofac) is broken down by blood esterases, not by cytochrome enzymes; amitriptyline is broken down by CYP2D6 and CYP2C19, which reishi did not inhibit in the dish. “Not tested” is not “safe” — tell your doctor about every supplement, even when there is no shared pathway on paper.

What does help IBS according to the research?

According to a network meta-analysis of 51 trials in 4,644 patients: peppermint oil (RR 0.63 for treatment failure) and low-dose amitriptyline (RR 0.66); psyllium is the only fiber that works (RR 1.53); the low-FODMAP diet is the only one that reduced bloating. Probiotics — moderate certainty only for Escherichia strains. We sell none of them; the dose and the choice belong to the physician.

Mushrooms “balance the microbiome” — doesn’t that help IBS?

What was measured is a change in the bacterial composition of the stool — in healthy volunteers only, and with no symptom tested: turkey tail in 24, shiitake in 52, lion’s mane in 13, button mushrooms in 32. In the button-mushroom trial there were actually more digestive symptoms on days 1–2. A change in composition is a marker, not an outcome; and in IBS, fermentation and gas are exactly what you do not want.

Does cordyceps cause diarrhea?

Not measured. A search for randomized human trials of cordyceps with diarrhea, the digestive system or adverse effects returns 7 records — meta-analyses in lung cancer, in dialysis and in kidney transplantation — and none measured digestive symptoms as an outcome. Cordyceps in IBS: 0 records, not even in animals. The answer is “not measured”, not “no”.

Scientific sources (peer-reviewed)

• The only study with “reishi” and “irritable bowel syndrome” in the same record — mice: ganoderic acid A in an IBS-like model (infection + stress) improved motility, visceral sensitivity and barrier; antibiotic treatment completely abolished the benefit — Kou RW, et al. Journal of Agricultural and Food Chemistry, 2026. View on PubMed
• 123 IBS patients, probiotics + lion’s mane + PEA + seaweed blend, 4 weeks, retrospective: Bristol 1.5→3.3 (constipation), 6.5→4.3 (diarrhea); VAS pain 6.7→2.8 (p<0.001). No control; three authors from the manufacturer — Romano A, et al. Journal of Dietary Supplements, 2024. View on PubMed
• Microbiomes of 8 IBS patients in an ex vivo system: a mushroom blend raised propionate; triacetin raised butyrate “with less gas production”; “fibers generally increase gas production and may worsen IBS symptoms”. Commercial laboratory — Van den Abbeele P, et al. International Journal of Molecular Sciences, 2025. View on PubMed
• 54 patients with symptomatic diverticulosis after rifaximin, multi-ingredient supplement with lion’s mane, one month, retrospective: bowel movements 3.8→2.18, pain 5.81→2.59. Not IBS, no control, manufacturer as author — Bertani L, et al. Minerva Gastroenterologica, 2026. View on PubMed
• Rome Foundation Global Study: 73,076 respondents in 33 countries; at least one disorder of gut-brain interaction — 40.3% (internet) / 20.7% (household); IBS Rome IV — 4.1% / 1.5%; Rome III — 10.1% / 3.5% — Sperber AD, et al. Gastroenterology, 2021. View on PubMed
• The only RCT of turkey tail on the human microbiome: 24 healthy adults (22 completed), PSP / amoxicillin / control, 8 weeks — “clear and consistent” changes, but “baseline microbiomes tended to overshadow treatment effects”; no symptom measure — Pallav K, et al. Gut Microbes, 2014. View on PubMed
• 13 healthy adults, lion’s mane powder 7 days, no control: alpha diversity rose, SCFA producers rose; “a physiological adaptation to 7 days of supplementation” — Xie XQ, et al. Nutrients, 2021. View on PubMed
• 32 healthy adults, crossover RCT, button mushrooms or meat twice a day for 10 days: “the mushroom diet led to more overall digestive symptoms on days 1 and 2”; higher stool weight (p=0.002); more Bacteroidetes (p=0.0002) — Hess J, et al. Nutrients, 2018. View on PubMed
• 52 adults with high cholesterol, 10.4 grams a day of a beta-glucan-enriched shiitake blend (3.5 grams of beta-glucans) or placebo, 8 weeks: microbiome changed; zero change in lipids and cytokines; “safe” — Morales D, et al. European Journal of Nutrition, 2021. View on PubMed
• Turkey tail extract in human fecal fermentation in vitro: Bifidobacterium and Lactobacillus rose; Clostridium, Staphylococcus, Enterococcus fell — Yu ZT, et al. Plant Foods for Human Nutrition, 2013. View on PubMed
• Lion’s mane beta-glucan in human fecal fermentation in vitro: the heavy fraction raised butyrate via Faecalibacterium; the light one — Lactococcus and total SCFA — Chen S, et al. Food Chemistry, 2025. View on PubMed
• Double-blind trial from 1985 of lion’s mane in chronic atrophic gastritis — “a preliminary report”; abstract not available on PubMed, no number taken from it — Xu CP, et al. Chinese Medical Journal, 1985. View on PubMed
• Review of lion’s mane in gastrointestinal diseases: “therapeutic potential” in gastritis and inflammatory bowel disease — mechanistic, no meta-analysis — Gravina AG, et al. World Journal of Gastroenterology, 2023. View on PubMed
• 2025 letter: “preliminary clinical data” in atrophic gastritis; “further evidence is needed before proposing the mushroom as a complementary approach” — Pellegrino R, Gravina AG. World Journal of Gastroenterology, 2025. View on PubMed
• Aqueous lion’s mane extract in rats with ethanol-induced stomach ulcer: ulcer area shrank, protective enzymes preserved; 5 grams per kg with no acute toxicity. Rats — Wong JY, et al. Evidence-Based Complementary and Alternative Medicine, 2013. View on PubMed
• Extracts and isolated compounds from lion’s mane inhibited H. pylori in vitro, MIC 6.25–400 micrograms per milliliter. A dish, not a stomach — Liu JH, et al. Journal of Ethnopharmacology, 2016. View on PubMed
• Reishi triterpene extract in mice in a colitis-associated cancer model, 4 months: tumor suppression — and lower expression of CYP1A2 and CYP3A4 in colon tissue — Sliva D, et al. PLoS One, 2012. View on PubMed
• Reishi dietary fiber with L. fermentum in mice with loperamide-induced constipation: more stool water, restored barrier. Loperamide here = the model’s toxin, not a co-administered drug — Wang C, et al. International Journal of Biological Macromolecules, 2025. View on PubMed
• Monash, RCT: 21 healthy controls + 20 IBS patients, 10 gram challenges of sorbitol/mannitol/glucose. Mannitol absorption 80% in IBS versus 43% (p=0.02); symptoms rose after both polyols in IBS patients only, independently of malabsorption. Mannitol “higher in certain vegetables” — Yao CK, et al. Journal of Human Nutrition and Dietetics, 2014. View on PubMed
• Monash — FODMAP cutoff values: polyols (mannitol, sorbitol), oligosaccharides, lactose, fructose; food processing changes content; mushroom values not in the abstract — Varney J, et al. Journal of Gastroenterology and Hepatology, 2017. View on PubMed
• 35 plant foods measured for FODMAP; 20 classified low-FODMAP; pickling reduced content the most. Mushrooms not in the abstract — a source for methodology — Tuck C, et al. Journal of Human Nutrition and Dietetics, 2018. View on PubMed
• 64 subjects, oral load of 25 grams of trehalose: 19 experienced clear symptoms; 2 with trehalase deficiency; “trehalose maldigestion can cause symptoms similar to lactose intolerance” — Arola H, et al. Scandinavian Journal of Gastroenterology, 1999. View on PubMed
• NMR of four mushrooms (including lion’s mane, fruiting body and mycelium): 54 metabolites including sugar alcohols; “trehalose was the dominant carbohydrate in most samples”; quantitative values not in the abstract — Chien RC, et al. International Journal of Medicinal Mushrooms, 2023. View on PubMed
• ATLANTIS: 463 IBS patients in 55 primary-care practices, amitriptyline 10–30 mg versus placebo, 6 months: IBS-SSS −27.0 (p=0.0079); “safe and well tolerated” — Ford AC, et al. Lancet, 2023. View on PubMed
• CPIC 2016 guideline: amitriptyline is affected by CYP2D6 and CYP2C19 genotype — Hicks JK, et al. Clinical Pharmacology & Therapeutics, 2017. View on PubMed
• Loperamide in human liver microsomes: CYP2B6, 2C8, 2D6 and 3A4; ketoconazole inhibited by 90%, quercetin by 40%; “the clinical significance requires study” — Kim KA, et al. European Journal of Clinical Pharmacology, 2004. View on PubMed
• Linaclotide: a peptide that is barely absorbed, converted in the small intestine to an active metabolite; 3–5% of the dose in stool as active peptide; low systemic exposure. Manufacturer as author — Busby RW, et al. Journal of Pharmacology and Experimental Therapeutics, 2013. View on PubMed
• Mebeverine is rapidly broken down by blood esterases to mebeverine alcohol and veratric acid — not by cytochrome enzymes — Elliott S, Burgess V. Journal of Analytical Toxicology, 2006. View on PubMed
• A reishi polysaccharide dose-dependently inhibited CYP2E1, CYP1A2 and CYP3A in rat liver microsomes; “pharmacokinetics may be altered in herb–drug interaction” — Wang X, et al. Biological & Pharmaceutical Bulletin, 2007. View on PubMed
• Retrospective review of 1,816 adverse-event reports: 30 cases of adaptogen × antidepressant; cordyceps with sertraline — upper gastrointestinal bleeding (one case); the case with amitriptyline — another plant — Siwek M, et al. Frontiers in Pharmacology, 2023. View on PubMed
• Network meta-analysis, 51 trials, 4,644 patients: peppermint oil RR 0.63 and TCA RR 0.66 for treatment failure; TCA for pain RR 0.53 on only 92 patients; TCA more adverse events RR 1.59 — Black CJ, et al. Lancet Gastroenterology & Hepatology, 2020. View on PubMed
• Peppermint oil, 10 trials, 1,030 patients: NNT 4 for global improvement; adverse events RR 1.57; quality of evidence “very low” — Ingrosso MR, et al. Alimentary Pharmacology & Therapeutics, 2022. View on PubMed
• Peppermint oil, 12 trials, 835 patients: global improvement RR 2.39; adverse events 9.3% versus 6.1% (not significant); NNT 3 — Alammar N, et al. BMC Complementary and Alternative Medicine, 2019. View on PubMed
• BMJ 2008: fiber RR 0.87 (psyllium only 0.78); antispasmodics 22 trials/1,778 RR 0.68 (otilonium 0.55, hyoscine 0.63); peppermint 4 trials/392 RR 0.43 — Ford AC, et al. BMJ, 2008. View on PubMed
• Fiber, 14 trials, 906 patients: RR 0.86, NNT 10; soluble fiber only RR 0.83, NNT 7; bran — neither helps nor harms — Moayyedi P, et al. American Journal of Gastroenterology, 2014. View on PubMed
• Fiber 2026, 30 trials, 1,904 patients: clinical response 52% versus 44% (RR 1.21); psyllium RR 1.53 — Staudacher HM, et al. Gastroenterology, 2026. View on PubMed
• Diets, network meta-analysis, 28 trials, 2,338 patients: low-FODMAP RR 0.51 for global improvement (24 trials), 0.61 for pain, and the only one that reduced bloating against a regular diet (RR 0.55); no diet changed bowel habit — Cuffe MS, et al. Lancet Gastroenterology & Hepatology, 2025. View on PubMed
• Probiotics, 82 trials, 10,332 patients, 24 at low risk of bias: moderate certainty for Escherichia strains; “low to very low in almost all analyses” — Goodoory VC, et al. Gastroenterology, 2023. View on PubMed
• Erinacine A-enriched lion’s mane mycelium, 3×350 mg a day, 49 weeks, double-blind: four subjects dropped out over abdominal discomfort, nausea and rash; denominator not stated. Grape King Bio — Li IC, et al. Frontiers in Aging Neuroscience, 2020. View on PubMed
• 30 subjects aged 50–80 with mild cognitive impairment, 3 grams a day, 16 weeks: “laboratory tests showed no adverse effect”; digestive symptoms not reported separately — Mori K, et al. Phytotherapy Research, 2009. View on PubMed
• 30 women, lion’s mane cookies 4 weeks: depression and anxiety fell from baseline; against placebo — two questionnaire items; adverse effects not in the abstract — Nagano M, et al. Biomedical Research (Tokyo), 2010. View on PubMed
• 41 healthy young adults, 1.8 grams of lion’s mane, 28 days: subjective stress p=0.051 — not significant; “limited null and negative findings were also observed” — Docherty S, et al. Nutrients, 2023. View on PubMed
• Lion’s mane fruiting body 12 weeks, cognition: only the MMSE improved; “safe and comfortable” — no detail on adverse effects — Saitsu Y, et al. Biomedical Research (Tokyo), 2019. View on PubMed
• 77 people with overweight and depression/anxiety/sleep disorders, 8 weeks of lion’s mane on a diet: mood and sleep improved; no placebo arm in the abstract — Vigna L, et al. Evidence-Based Complementary and Alternative Medicine, 2019. View on PubMed
• 2016 Cochrane review of reishi in cancer: minimal adverse effects — nausea and insomnia; no hematological or hepatic toxicity — Jin X, et al. Cochrane Database of Systematic Reviews, 2016. View on PubMed
• Survey of 1,374 cancer patients taking reishi: 9.1% adverse effects — dry mouth 5%, constipation 4%, insomnia 3%, itching 3%, vertigo 3%; 55% “nausea improved”. No control — Li X, et al. Integrative Medicine Research, 2024. View on PubMed
• 2015 Cochrane review: 5 trials, 398; RR 1.67 (0.86–3.24) for any adverse effect — not significant, not serious — Klupp NL, et al. Cochrane Database of Systematic Reviews, 2015. View on PubMed

Read next

• Medicinal mushrooms by goal — the hub
• Medicinal mushrooms and the digestive system
• Medicinal mushrooms and gut health
• Is turkey tail good for the gut?
• Fibromyalgia and supplements — Lyrica and Cymbalta
• Reishi for stress and anxiety
• Lion’s mane and brain fog
• Who shouldn’t take lion’s mane
• Who shouldn’t take reishi
• Who shouldn’t take cordyceps
• Drug interactions
• Do medicinal mushrooms have side effects?
• Research hub — turkey tail
• Lab results — beta-glucan
• How to read a test report (COA)

This page is educational and does not constitute medical advice, diagnosis or a substitute for professional care. Medicinal mushroom extracts are dietary supplements, not drugs, and are not intended to treat irritable bowel syndrome or any other medical condition. IBS is diagnosed by a physician after other conditions have been ruled out; blood in the stool, weight loss, fever or symptoms that wake you at night require a doctor’s visit. Do not stop, replace or change the dose of any medication without your treating physician’s guidance. It describes what published trials and case reports recorded — and what was not recorded; it is not a prediction of what any individual will experience, and it is not a recommendation to start, stop or combine any supplement with any medication — those decisions belong with your physician, especially if you take regular medication, are pregnant or breastfeeding, have surgery planned, or have liver or kidney disease. *These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.*