Polygala tenuifolia, called yuan zhi in Chinese medicine, is a plant whose root has been used for centuries as a calming herb. A Korean root extract called BT-11 has been tested for memory.
Also known as: Polygala, yuan zhi, Chinese senega root, BT-11, onjisaponin.
A safety trial in 9 to 19 year olds used 300 mg a day of BT-11 for 12 weeks (Park 2019). The memory trials gave capsules three times a day for 4 weeks (Lee 2009). These are study protocols, not a recommendation.
The NIH Dietary Supplement Label Database lists Polygala tenuifolia products such as one from Nootropics Depot as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling.
What studies show: in a 4-week placebo-controlled trial in healthy adults, BT-11 improved immediate recall on a word-list test and reduced errors on a working-memory test compared with placebo (Lee 2009). In 53 older adults, total scores on a dementia test battery rose more with BT-11 than with placebo (Shin 2009). Both trials were small and came from the same Seoul research group, and we found no larger trials.
Safety: in 121 young people aged 9 to 19, 300 mg a day for 12 weeks caused no more side effects than placebo and did not change lab tests or heart tracings; several authors worked for GDFI Braincell Laboratory (Park 2019). The sources here do not describe drug interactions.
We could not find a single published half-life or time to peak for Polygala tenuifolia that applies to a supplement dose, so we do not list one. Plant extracts are mixtures of many compounds, so no single figure would describe them.
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