Pueraria mirifica is an herb that has traditionally been used in Thai medicine as a vitality enhancer, particularly for older women, and holds promise in treating menopausal symptoms.
Pueraria mirifica has a large amount of phytoestrogenic compounds, particularly isoflavones. It also has a class of molecules known as chromenes, and the molecules in this class (miroestrol, isomiroestrol and deoxymiroestrol) have a potency that is similar to estrogen.
There is currently no evidence, however, to support the view that this herb is safer than estrogen replacement therapy. Further research will help shed light on the benefits and risks.
Pueraria mirifica helps treat menopausal symptoms. Changing hormones during and after menopause can cause a range of symptoms, including hot flashes, urinary tract infections, insomnia, urinary problems and mood changes (1).
In a recent study, researchers compared Pueraria mirifica’s efficacy in treating menopausal symptoms when given at doses of 25 and 50 mg for six months. Fifty-two women with menopausal symptoms were randomized to one of the two groups.
Both dosages of Pueraria mirifica were found to be equally effective and safe in the treatment of menopausal symptoms (2).
In another study, 50 and 100 mg of Pueraria mirifica (taken once a day for six months) alleviated hot flashes and night sweats in a group of perimenopausal women (3). Perimenopause refers to the period before menopause when a woman begins to experience fluctuations in her menstrual cycle.
In a study evaluating the effect of Pueraria mirifica on vaginal dryness (a common symptom in postmenopausal women), researchers found an improvement in vaginal dryness symptoms as well as painful intercourse. Healthy postmenopausal women, age 45 to 60 years old, were included in the study lasting 24 weeks.
There were no adverse effects reported in this study (4).
While further blinded and placebo studies are needed to confirm this supplement’s role in reducing menopausal symptoms, results so far are promising.
Pueraria mirifica may improve bone loss in postmenopausal women.
Increased bone turnover in late postmenopausal women is a major determinant of osteoporosis. According to the results of a study published in the Journal of Bone and Mineral Research, Pueraria mirifica at doses of 20, 30, and 50 mg/day for a 24-week period demonstrated an estrogen-like effect on bone turnover rate (5,6).
In another study performed on estrogen-deficient rats, supplementation proved to be an efficacious anti-osteoporotic agent; researchers specifically noted that Pueraria mirifica could mainly retain bone mass at the levels before bone loss was initiated (7).
Pueraria mirifica may improve cholesterol levels. Estrogen is believed to have a positive effect on the inner layer of artery walls, helping to keep blood vessels flexible. According to the American Heart Association, a decline in the natural hormone estrogen may be a factor in heart disease increase among postmenopausal women (8).
In a randomized, double-blind, placebo-controlled clinical trial, 19 postmenopausal women were randomly assigned to receive oral administration of Pueraria mirifica powder or placebo.
After two months, the treatment group showed an increase in serum concentrations of high-density lipoprotein (good) cholesterol (34 percent), and a decrease in low-density lipoprotein (bad) cholesterol (17 percent) 9.
Pueraria mirifica may have neuroprotective activity. Neurodegenerative disease is a broad term for a range of conditions that primarily affect the neurons in the human brain. Alzheimer’s disease, Parkinson’s disease, Huntington’s disease and amyotrophic lateral sclerosis (ALS) all fall under the umbrella of neurodegenerative diseases (10).
When studying the neuroprotection potential of an ethyl acetate-ethanol extract of Pueraria mirifica root, researchers have found it to have considerable antioxidant activity with significant neuroprotective capabilities.
Studies of the extract’s possible mechanisms of action indicate that the neuroprotection exerted is related to its scavenging activity against reactive oxygen species — a buildup of reactive oxygen species in cells may cause damage to DNA, RNA, and proteins and may cause cell death (11,12).
Pueraria mirifica may play a future role in fighting cancer. Phytoestrogens have been reported to exhibit antiproliferation to human breast cancer cells in vitro. Armed with this information, researchers recently tested phytoestrogen-rich, Pueraria mirifica against rat breast cancer.
Rats were pretreated with a dosage of 0, 10, 100 and 1000 mg/kg bodyweight/daily for four consecutive weeks. Tumor development was then induced followed by a weekly examination for size and multiplication of tumors for 20 weeks.
Pretreatment of 1000 mg/kg bodyweight resulted in a decrease in rat tumor development (13).
In human studies, doses up to 50mg have been used with no significant reported side-effects; doses in the range of 25-100mg in studies lasting up to six months also did not show any relevant toxic effects.
The long-term effects are unknown.
A six-month chronic toxicity study performed in rats showed that among the tested doses (10, 50 and 250 mg/kg/day), only the lowest dose (10 mg/kg/day) did not cause any adverse hematological and biochemical alterations (14).
In one animal study, high doses led to reproductive disorders and decreased fertility in male mice; the effects were temporary, however, and improved once treatment ended (15).
Researchers also point out that the potency of this herb suggests that it may carry the same risks as estrogen replacement therapy.
In addition, due to it being highly estrogenic, it should not be used in those with high cancer risk or survivors of cancer of the breast or uterus.
While most studies on humans using 20 mg, 30 mg or 50 mg daily doses saw no significant toxic effects, further research is needed before recommending an efficacious and safe dose.
Pueraria mirifica is an herb that holds promise in treating symptoms of menopause. It has a high amount of phytoestrogenic compounds and its main bioactives (namely miroestrol, isomiroestrol and deoxymiroestrol) are similar in potency to estrogen. It is often referred to as the standard “herbal estrogen replacement therapy” due to its potency.
While various animal and cell studies have proven this herb’s phytoestrogen effects, few extensive human clinical trials have been conducted. Further research is needed before it can be recommended as a safe treatment for menopausal women.
In addition to improving hot flashes, night sweats, bone loss and cholesterol levels, supplementation may provide some neuroprotective and cancer-preventing activity.
Supplementation appears to be safe with short-term use, however, more studies are needed to determine its safety, especially with long-term use.