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Limited evidenceImmunity

Maitake

Maitake (Grifola frondosa) has the most interesting small trials of the culinary medicinal mushrooms — a phase I/II study showing dose-dependent immune changes in breast cancer patients, and a small ovulation-induction trial in PCOS — but nothing has been replicated at scale. Promising, unproven.

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What the science says

  • Immune modulation is dose-dependent but bidirectional Limited evidence

    A phase I/II dose-escalation trial in 34 postmenopausal breast cancer survivors gave oral maitake polysaccharide extract for 3 weeks and found statistically significant changes in ex vivo cytokine production that were non-monotonic: some immune parameters increased at intermediate doses while others were suppressed at the highest doses. The authors explicitly warned that more is not better and that clinical significance is unknown.

  • Ovulation induction in PCOS Limited evidence

    An open randomized trial in 80 women with PCOS reported ovulation in 77% of cycles on maitake SX-fraction versus 94% on clomiphene citrate, and 6 of 8 clomiphene non-responders ovulated when maitake was added. This was unblinded, single-centre, and never replicated; it is a signal worth studying, not a reason to substitute maitake for fertility treatment.

  • Blood glucose and insulin sensitivity Limited evidence

    The 'SX-fraction' glucose claim rests on rodent work and a handful of small uncontrolled human series; there is no adequately powered placebo-controlled trial showing improved HbA1c or fasting glucose in humans. Do not use it in place of established glycemic therapy.

  • Myelodysplastic syndrome and blood counts Limited evidence

    A phase II study of maitake extract in 21 patients with myelodysplastic syndrome found enhanced neutrophil and monocyte function ex vivo, but no meaningful change in blood counts or transfusion requirements. Functional assay changes without hematologic improvement is the recurring pattern in maitake research.

Dosage & safety

Studied doseTrials used purified fractions, not the whole mushroom: the breast cancer study escalated from 0.1 to 5 mg/kg twice daily of polysaccharide extract; the PCOS study used maitake SX-fraction at roughly 18 mg three times daily. Commercial capsules typically supply 500-1,200 mg/day of unstandardized extract, which does not map onto any studied fraction. Culinary intake is 50-100 g fresh mushroom.
SafetyWell tolerated in short trials; reported effects are mild GI upset and, occasionally, low blood pressure. Two real interaction concerns: maitake may add to the glucose-lowering effect of insulin and oral hypoglycemics (monitor if diabetic), and case-level evidence suggests potentiation of warfarin with raised INR — avoid or monitor closely on anticoagulants. Given the bidirectional immune effects seen in trials, use caution in autoimmune disease and in transplant recipients, and clear it with an oncologist before combining with chemotherapy or immunotherapy. Long-term safety beyond a few months is uncharacterized. Not banned in sport.

How to take it

TimingTiming does not matter; the studied fractions were dosed two or three times daily.
With food?Take it with food, which reduces the mild GI upset reported in trials.
Worth knowingCommercial capsules are unstandardized whole extract and do not map onto the purified fractions used in trials, so the label dose is not the studied dose.

Interactions

With medications

  • warfarin and other anticoagulants

    A published case documented a marked INR rise when maitake extract was added to warfarin. avoid it, or have INR checked closely if your prescriber agrees to the combination

  • insulin and oral hypoglycaemics

    Maitake may add to the glucose-lowering effect and push blood sugar too low. monitor glucose closely if you are diabetic

  • immunosuppressants and transplant medication

    Trials show bidirectional immune effects, which is not something to add to deliberate immune suppression. do not combine without specialist approval

With other supplements

  • berberine, cinnamon and other glucose-lowering supplements

    Additive glucose lowering on top of any diabetes medication. monitor glucose if you stack them

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does maitake mushroom help PCOS?

The evidence is limited: in one open trial of 80 women with PCOS, maitake SX-fraction produced ovulation in 77% of cycles versus 94% on clomiphene, and 6 of 8 clomiphene non-responders ovulated when maitake was added. It was unblinded and never replicated, so maitake is not a substitute for fertility treatment.

Does maitake lower blood sugar?

Not proven: maitake's glucose claim rests on rodent work and small uncontrolled human series, with no placebo-controlled trial showing better HbA1c or fasting glucose. Maitake may still add to insulin or oral hypoglycemics, so monitor glucose if you are diabetic.

Does maitake boost immunity in cancer patients?

The evidence is limited: in 34 breast cancer survivors, maitake extract changed immune measures in both directions, raising some at intermediate doses and suppressing others at the highest doses. The clinical significance is unknown, and more maitake is not better.

Is maitake safe with warfarin?

Avoid it or monitor closely: a published case documented a marked INR rise when maitake extract was added to warfarin. Also do not combine maitake with immunosuppressants without specialist approval.

Scientific references

Where to buy

Vitacost, Root2, Maitake Mushroom Extract, 500 mg, 100 Capsules

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