Polygala tenuifolia is an herb with potential nootropic properties. Human studies are few but show that it improves memory in healthy people and cognitive function in the elderly. Animal studies show that this herb may effectively improve depression, anxiety, and sleep. Read on to learn about the other benefits of this plant. You may find some of them surprising.

What Is Polygala tenuifolia?

Polygala tenuifolia, also known as yuan zhi, is an herb. Its root is widely used in Chinese medicine to improve memory and combat forgetfulness and aging [1].

Polygala root contains many beneficial neuroprotective and anti-inflammatory compounds, including:

  • Tenuifolisides increase BDNF and suppress inflammatory cytokines (TNF-alpha, IL-1beta) and other inflammation-causing agents (NF-kB, PGE2, iNOs, COX2) [2, 3].
  • 3,6-Disinapoylsucrose increases BDNF and activates CREB [4].
  • Polygala saponins activate TrkB (the BDNF receptor) and prevent the decrease in NMDA receptors in aged animals [5, 6].

Polygala tenuifolia Health Benefits

1) Polygala tenuifolia Improves Memory

In a study (DB-RCT) with 48 healthy people, polygala improved spatial and verbal memory. Those who received it also made fewer errors and scored better on the test measuring working memory [7].

Polygala extract improved both spatial and non-spatial memory in aged mice [8].

It also improved short-term memory in rats with drug-induced memory impairment [9].

This supplement improves memory by:

  • Inhibiting the enzyme acetylcholinesterase (AChE). This reduces the breakdown of acetylcholine [10].
  • Inhibiting MAO enzymes. This reduces the breakdown of dopamine, serotonin, and norepinephrine [8].
  • Increasing BDNF in the brain (hippocampus) [11].
  • Promoting the growth of new neurons in the hippocampus (important for the creation of new memories) [12].

2) Polygala tenuifolia May Improve Cognitive Function in the Elderly

In a study (DB-RCT) with 53 elderly subjects, polygala extract enhanced cognitive function [13].

Polygala extract also reversed cognitive impairments in rat models of Alzheimer’s disease, and mice models of stroke [10, 14].

3) Polygala tenuifolia May Combat Depression

Polygala and its derivatives have antidepressant effects in rats and mice [15, 16, 17, 18, 19].

In mice, a saponin from polygala was more effective than a drug used to treat depression (duloxetine) [18].

Animal studies show that polygala combats depression by:

4) Polygala tenuifolia May Reduce Anxiety

Mice treated with saponins derived from polygala showed signs of reduced anxiety [20].

5) Polygala tenuifolia Is Anti-Inflammatory

Polygala and its derivatives reduced the production of inflammatory cytokines TNF-alpha, IL-1beta, and the master-regulator of inflammation NF-κB in white blood cells (macrophages) [21, 2].

Polygala also reduces the production of nitric oxide (NO) and iNOS, thereby reducing inflammation [21].

6) Polygala tenuifolia May Improve Sleep

Tenuifolin, derived from polygala, has sleep-enhancing effects in mice. It prolongs both REM and NREM sleep [22].

Polygala saponins also had sedative effects and prolonged sleep in mice [20].

7) Polygala tenuifolia May Be Antipsychotic

Polygala saponins reduced drug-induced hyperactivity in mice and rats. They may act by blocking serotonin and dopamine receptors [23].

In addition, polygala extract reduces cocaine-induced psychotic behavior in mice [24].

8) Polygala tenuifolia May Help with Dermatitis

Its extract reduces stress-induced dermatitis in mice [25].

9) Polygala tenuifolia May Help Combat Cancer

Polygala compounds killed human ovarian and lung cancer cells [26, 27, 28].

They also suppressed tumor growth in mice [29, 28].

Risks and Side Effects

Polygala may cause vomiting, changes in body weight, and/or mild indigestion [30, 7].

There was one case where polygala caused occupational asthma and rhinitis due to long-term inhalation [31].


Polygala is available as powder or as capsules.

Healthy adults can take up to 300 mg of polygala per day. In clinical trials, it was administered as 100 mg per dose 3 times a day [7].

User Experience

Users of polygala reported:

  • Mood boost and antidepressant effects
  • Calming effects
  • Sleep improvement

However, some also experienced:

  • Nausea
  • Stomach irritation
  • Brain fog

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About the Author

Biljana Novkovic - PHD (ECOLOGICAL GENETICS) - Writer at Selfhacked

Dr. Biljana Novkovic, PhD

PhD (Ecological Genetics)

Biljana received her PhD from Hokkaido University.

Before joining SelfHacked, she was a research scientist with extensive field and laboratory experience. She spent 4 years reviewing the scientific literature on supplements, lab tests and other areas of health sciences. She is passionate about releasing the most accurate science & health information available on topics, and she's meticulous when writing and reviewing articles to make sure the science is sound. She believes that SelfHacked has the best science that is also layperson-friendly on the web.

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