Polygala tenuifolia is an herb with potential nootropic properties. Unfortunately, there are very few human studies. Although their results are promising, the evidence is insufficient to support its effectiveness at improving 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 potential benefits of this plant.
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 potentially 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].
Snapshot
Proponents
- Preliminary research suggests it may improve memory in healthy people and cognitive function in elderly people
- Few mild adverse effects reported
Skeptics
- Insufficient evidence for all benefits
- Relatively unknown safety profile
Health Benefits
Insufficient Evidence for:
1) Improving Memory
In a clinical trial on 48 healthy people, Polygala tenuifolia root extract improved spatial and verbal memory. Those who received it also made fewer errors and scored better on a test measuring working memory [7].
Similarly, Polygala tenuifolia 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 and mice poisoned with manganese [9, 10].
This supplement may improve memory by:
- Inhibiting the enzyme acetylcholinesterase (AChE), which reduces the breakdown of acetylcholine [11].
- Inhibiting MAO enzymes. This reduces the breakdown of dopamine, serotonin, and norepinephrine [8].
- Increasing BDNF in the brain (hippocampus) [12].
- Promoting the growth of new neurons in the hippocampus (important for the creation of new memories) [13].
A single clinical trial and some animal and cell-based research cannot be considered sufficient evidence to conclude for certain that Polygala tenuifolia improves memory. More clinical studies on larger populations are needed to confirm these preliminary findings.
2) Improving Cognitive Function in the Elderly
In a clinical trial on 53 elderly subjects, Polygala tenuifolia root extract enhanced cognitive function [14].
Polygala tenuifolia extract also reversed cognitive impairments in rats with Alzheimer’s disease and mice recovering from a stroke [11, 15].
Again, only one clinical trial and some animal research support the use of Polygala tenuifolia to improve cognitive function in elderly people. Further clinical research is required.
Animal and Cell Research (Lack of Evidence)
No clinical evidence supports the use of Polygala tenuifolia for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies listed below should not be interpreted as supportive of any health benefit.
Depression
Polygala tenuifolia and its derivatives had antidepressant effects in rats and mice [16, 17, 18, 19, 20].
In mice, a saponin from its extract was more effective than a drug used to treat depression (duloxetine) [19].
Animal studies show that Polygala tenuifolia may combat depression by:
- Blocking MAO enzymes. This increases dopamine and serotonin levels [16, 19]
- Increasing antioxidant enzymes (SOD) [16]
- Decreasing cortisol and the stress response (HPA axis) [16, 17]
Sleep
Tenuifolin, derived from this plant, had sleep-enhancing effects in mice. It prolonged both REM and NREM sleep [21].
Polygala tenuifolia saponins also had sedative effects and prolonged sleep in mice [22].
Antipsychotic
Polygala tenuifolia saponins reduced drug-induced hyperactivity in mice and rats. They may act by blocking serotonin and dopamine receptors [23].
In addition, an extract of this plant reduced cocaine-induced psychotic behavior in mice [24].
Anxiety
Mice treated with saponins derived from Polygala tenuifolia showed signs of reduced anxiety [22].
Dermatitis
The extract of this plant reduced stress-induced dermatitis in mice [25].
Anti-Inflammatory
Polygala tenuifolia 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) [26, 2].
Polygala tenuifolia also reduced the production of nitric oxide (NO) and iNOS, thereby reducing inflammation [26].
Cancer
Below, we will discuss some preliminary research on Polygala tenuifolia’s potential anticancer effects. It’s still in the animal and cell stage and further clinical studies have yet to determine if its extract may be useful in cancer therapies.
Do not under any circumstances attempt to replace conventional cancer therapies with Polygala tenuifolia or any other supplements. If you want to use it as a supportive measure, talk to your doctor to avoid any unexpected interactions.
Polygala tenuifolia compounds suppressed tumor growth in mice [27, 28].
They also killed human ovarian and lung cancer cells [29, 30, 28].
Risks and Side Effects
Keep in mind that the safety profile of Polygala tenuifolia is relatively unknown, given the lack of well-designed clinical studies. The list of side effects below is not a definite one and you should consult your doctor about other potential side effects based on your health condition and possible drug or supplement interactions.
Polygala tenuifolia has been reported to cause vomiting, diarrhea, changes in body weight, and/or mild indigestion in clinical trials [31, 7, 32].
There was one case where it caused occupational asthma and rhinitis due to long-term inhalation [33].
Dosage
Because Polygala tenuifolia is not approved by the FDA for any conditions, there is no official dose. Users and supplement manufacturers have established unofficial doses based on trial and error. Discuss with your doctor if it may be useful as a complementary approach in your case and which dose you should take.
Polygala tenuifolia is available as a powder or as capsules.
Healthy adults can take up to 300 mg per day. In clinical trials, it was administered as 100 mg per dose 3 times a day [7].
The same dose was generally safe in a clinical trial on 60 children and teenagers aged 9-19 [32].
User Experience
The opinions expressed in this section are solely those of Polygala tenuifolia users, who may or may not have medical or scientific training. Their reviews do not represent the opinions of SelfHacked. SelfHacked does not endorse any specific product, service, or treatment.
Do not consider user experiences as medical advice. Never delay or disregard seeking professional medical advice from your doctor or another qualified healthcare provider because of something you have read on SelfHacked. We understand that reading individual, real-life experiences can be a helpful resource, but it is never a substitute for professional medical advice, diagnosis, or treatment from a qualified healthcare provider.
Satisfied users of Polygala tenuifolia reported:
- Mood boost and antidepressant effects
- Calming effects
- Sleep improvement
However, a few users complained about:
- Nausea
- Stomach irritation
- “Brain fog”
