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Limited evidenceBrain & cognition

Polygala Tenuifolia

A Chinese root traditionally used for memory and restlessness. One small human trial of a standardized extract reported cognitive gains in older adults; everything else is preclinical.

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What the science says

  • Memory in older adults Limited evidence

    A randomized controlled study of a standardized Polygala tenuifolia root extract (BT-11) in elderly volunteers reported improvement on memory and attention tests versus placebo. The sample was small, the trial short, and no independent replication has been published.

  • Tolerability Limited evidence

    A randomized safety study of the same extract in people aged 9 to 19 found no clinically important adverse changes over the study period. Safety data in older adults and with long-term use remain thin.

  • Neuroprotection Limited evidence

    A review of Radix Polygalae describes anti-inflammatory, anti-amyloid and neurotrophic activity in cell and rodent models. None of this has been tested against a clinical endpoint in humans.

Dosage & safety

Studied doseHuman trials used a standardized root extract; supplement labels typically give 100–300 mg/day of extract or 3–9 g/day of dried root in traditional decoctions. No optimal dose is established.
SafetyThe saponin content commonly causes nausea, vomiting and stomach irritation, and the root is traditionally avoided in gastritis and peptic ulcer disease. It has been reported to have uterine-stimulating activity and should be avoided in pregnancy. Interactions with sedatives and with drugs metabolised by the liver have not been characterised.

How to take it

TimingTiming does not matter - no optimal schedule has been established for any preparation.
With food?Always with food; the saponin content causes nausea, vomiting and stomach irritation on an empty stomach, and this is the main reason people stop taking it.
Worth knowingSkip it entirely if you have gastritis, reflux or a history of peptic ulcer - the root is traditionally contraindicated in exactly those conditions for good reason.

Interactions

With medications

  • benzodiazepines, z-drugs, sedating antihistamines and alcohol

    Polygala is traditionally a sedating, calming herb, and the combination has never been characterised. use caution, avoid the combination where you can, and do not drive until you know how it affects you

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

Frequently asked questions

Does polygala tenuifolia improve memory?

The evidence is limited: one small, short trial of a standardised Polygala tenuifolia extract (BT-11) in older adults reported better memory and attention test scores, with no independent replication.

Does polygala tenuifolia have side effects?

Polygala tenuifolia's saponins commonly cause nausea, vomiting and stomach irritation, so take it with food and skip it if you have gastritis, reflux or a peptic ulcer. Avoid it in pregnancy.

How much polygala should I take?

No optimal dose of Polygala tenuifolia is established; labels typically give 100-300 mg/day of extract, and traditional decoctions use 3-9 g/day of dried root.

Scientific references

Related in Brain & cognition

Herbal medicines: what the evidence says (335)