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Polygala tenuifolia

Polygala tenuifolia is a root used in traditional Chinese medicine for its ability to improve memory and protect against cognitive ailments. Limited human evidence suggests Polygala tenuifolia cannot improve memory, but may improve spatial awareness and organization.

Our evidence-based analysis on polygala tenuifolia features 77 unique references to scientific papers.

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Summary of Polygala tenuifolia

Primary information, health benefits, side effects, usage, and other important details

Polygala tenuifolia, also known as Yuan Zhi, is a root used in Traditional Chinese Medicine.

It has traditionally been used for its protective effects on the brain.

Preliminary animal evidence suggests that Polygala tenuifolia has an antidepressant effect in rats. Polygala tenuifolia_ may improve cognition, but more research is needed to confirm this effect.

Rodent research suggests that Polygala tenuifolia is similar in mechanism and effectiveness to ketamine, which interacts with N-methyl-D-aspartic acid and its receptors. Rodent studies assessing Polygala tenuifolia’s anti-amnesiac and adaptogen-like properties suggest that the herb can increase the level of compounds responsible for brain growth, like nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF).

Though Polygala tenuifolia supplementation may slightly increase cognitive ability in elderly people, it has limited effect on healthy adults. Supplementing Polygala tenuifolia can improve spatial organization and recognition, but it does not improve short- or long-term memory formation, as measured by free or cued recall. Much more research is needed to determine if Polygala tenuifolia qualifies as a nootropic.

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How to Take

Recommended dosage, active amounts, other details

The only human studies on Polygala tenuifolia have used 100mg of an ethanolic extract called BT-11, three times a day, for a total daily dose of 300mg.

A traditional Chinese medicine remedy suggests taking 3-9 g (dry weight) of Polygala tenuifolia root through a water decoction, like tea or soup, to reduce forgetfulness.

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Human Effect Matrix

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The Human Effect Matrix summarizes human studies to tell you what effects Polygala tenuifolia has on your body, how much evidence there is, and how strong these effects are.

Full details are available to Examine members.
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
grade-c Minor Moderate See 2 studies
A possible reduction in cognitive decline as assessed by CEMAD scores, although MMSE scores did not experience a significant benefit with supplementation at this moment in time.
grade-c Minor - See study
There appears to be an increase in spatial processing seen with supplementation in otherwise healthy humans due to less errors on spatial organizational tasks.
grade-c Minor - See study
BT-11 appears to have some efficacy in improving immediate recall in otherwise healthy adults, although it did not have this efficacy in short term recall (cued or free)
grade-c - Very High See 2 studies
There have been no detectable increases in long term (20 minute) recall, either with or without cues, associated with supplementation at this point in time.
grade-c - - See study
No significant improvements in verbal fluency noted in elderly adults with memory complaints supplementing this herb.

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Things to Note

Other Functions:

Also Known As

Yuan Zhi, Chinese Senega

Do Not Confuse With

Schizonepeta tenuifolia (different plant family)

  • Traditional Chinese medicine tends to use the root (dry weight) in a varying dose of 3-9 grams each day, consumed either straight or usually via some manner of hot water extraction (such as soup or tea)

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Click here to see all 77 references.