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 .
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 .
- 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 .
Polygala extract improved both spatial and non-spatial memory in aged mice .
It also improved short-term memory in rats with drug-induced memory impairment .
This supplement improves memory by:
- Inhibiting the enzyme acetylcholinesterase (AChE). This reduces the breakdown of acetylcholine .
- Inhibiting MAO enzymes. This reduces the breakdown of dopamine, serotonin, and norepinephrine .
- Increasing BDNF in the brain (hippocampus) .
- Promoting the growth of new neurons in the hippocampus (important for the creation of new memories) .
2) Polygala tenuifolia May Improve Cognitive Function in the Elderly
In a study (DB-RCT) with 53 elderly subjects, polygala extract enhanced cognitive function .
3) Polygala tenuifolia May Combat Depression
In mice, a saponin from polygala was more effective than a drug used to treat depression (duloxetine) .
Animal studies show that polygala combats depression by:
- Blocking MAO enzymes. This increases dopamine and serotonin levels [15, 18]
- Increasing antioxidant enzymes (SOD) 
- Decreasing cortisol and the stress response (HPA axis) [15, 16]
4) Polygala tenuifolia May Reduce Anxiety
Mice treated with saponins derived from polygala showed signs of reduced anxiety .
5) Polygala tenuifolia Is Anti-Inflammatory
6) Polygala tenuifolia May Improve Sleep
Tenuifolin, derived from polygala, has sleep-enhancing effects in mice. It prolongs both REM and NREM sleep .
Polygala saponins also had sedative effects and prolonged sleep in mice .
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 .
8) Polygala tenuifolia May Help with Dermatitis
9) Polygala tenuifolia May Help Combat Cancer
Risks and Side Effects
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 .
Users of polygala reported:
- Mood boost and antidepressant effects
- Calming effects
- Sleep improvement
However, some also experienced:
- Stomach irritation
- Brain fog
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