What is Pueraria mirifica?
Also known as White Kwao Krua, Pueraria mirifica is a medicinal plant that originates in Thailand. For centuries in Thailand, the anti-aging qualities of Pueraria mirifica were observed 
Pueraria mirifica is a woody plant that climbs as it grows. The real interest is in the roots, which are large tubular structures that contain many starch granules and are white on the inside .
The roots contain a component called phytoestrogens, which are a plant compound that mimics the results of the female hormone estrogen. At least 17 phytoestrogens have been identified, which can be categorized into isoflavonoids, coumestans, and chromenes. The most powerful and common phytoestrogen in Pueraria mirifica is miroestrol .
There are different phytoestrogen contents, which are controlled by the location of breeding and type of plant .
The phytoestrogen content depends on the age of the plant. Older plants have more consistent and substantial phytoestrogen content. One study determined plants that were 3 years old were best for use as supplements .
Also, plants harvested in the summer had a much higher phytoestrogen content than in the rainy and winter seasons .
In Pueraria mirifica herbs, the phytoestrogens are found in the leaves, stems, and roots. However, the phytoestrogen content is much larger in the roots .
Mechanism of Action
The phytoestrogen content of Pueraria mirifica mimics the effects of the hormone estrogen. These mimicked effects cause the observed effects .
Health Benefits of Pueraria mirifica
1) Pueraria mirifica Helps Relieve Menopause Symptoms
In a clinical trial of 5 volunteers, an oral supplement of P. mirifica reduced symptoms of menopause. Patients received a 200 mg daily dose for 4 months, followed by 200 mg every 2 days. These patients showed significant decreases in menopausal symptoms, including :
- Hot flashes
- Sleep disorders
- Skin dryness
- High blood cholesterol levels
- Absent Periods
- Irregular periods
In one study (DB-RCT) of 71 healthy postmenopausal women, the women received either a placebo or 20 mg, 30 mg, or 50 mg of Pueraria mirifica supplement. Pueraria mirifica was effective at decreasing vaginal dryness .
2) Pueraria mirifica Helps Protect Bone
Pueraria mirifica may potentially treat osteoporosis in both women and men.
In a study (DB-RCT) of 71 postmenopausal women, 24 weeks of P. mirifica supplements improved their bone structure. The phytoestrogens slowed bone deterioration .
In both male and female rats, P. mirifica supplementation also helped prevent bone loss .
3) Pueraria mirifica Benefits the Heart
Postmenopausal women have a decreased ability to process fats. This can lead to fat deposits in arteries and veins, which increase heart disease risk. In a study (DB-RCT) of 19 postmenopausal women, oral ingestion of Pueraria mirifica powder improved heart function. After 2 months of treatment, the women had a better ability to processing fats and improved heart function .
Similarly, in rabbits, P. mirifica improved heart function and reduced heart disease risk .
4) Pueraria mirifica Has Antioxidant Activities
In mice, miroestrol extracts from Pueraria mirifica improved antioxidant activity and had beneficial effects on the antioxidant activities in the liver. Pueraria mirifica may be beneficial as a replacement for hormone therapy to increase antioxidant activities .
5) Pueraria mirifica Is Potentially Anticancer
In mice, pretreatment of a high dose of P. mirifica 4 weeks before treatment of a tumor decreased tumor development. Another rat study determined that pretreatment of P. mirifica prevented the development of breast cancer [14, 14].
In cells, purified phytoestrogens of Pueraria mirifica killed breast cancer cells and stopped them from spreading. The phytoestrogens are toxic to cells and have the potential to help fight cancer .
However, when given a carcinogen, high levels of this plant promoted breast cancer in rats .
6) Pueraria mirifica May Help Improve Brain Function
In rats, Pueraria mirifica supplementation increased the strength of signals sent between neurons. This means that it can increase the effectiveness and efficiency of brain function .
In another rat study, early treatment with P. mirifica decreased brain function impairment .
Using Pueraria mirifica
Pueraria mirifica is most commonly taken orally, usually in pill form. Traditionally, pills are made of finely ground root powder, but some commercial brands use the root extract .
In mice, P. mirifica did not have toxic effects when the supplement was given to them in a powder form. When treated with a proportional dose to ones taken by humans, no abnormalities were found. But, when the dose was substantially increased, they found abnormalities in the blood .
Limitations and Caveats
Various mice and cell studies have proven this herb’s phytoestrogen effects. Few extensive human clinical trials have been conducted, so it is difficult to predict the long-term effects of Pueraria mirifica.
One user said she had a quick decrease in her menopausal symptoms.
Many users have claimed that Pueraria mirifica has enlarged their breasts.
One user said that after taking Pueraria mirifica they began to shake and felt weak as if they needed to eat something.
Another user said that after taking a Pueraria mirifica supplement, they felt weak and their heart hurt.