Supplement analysis backed by scientific evidence · PT

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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.

Evidence last reviewed: August 2026

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.

Scientific references

Where to buy

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