Benefits
Vaginal dryness after menopause
In a 24-week placebo-controlled trial in 71 healthy postmenopausal women aged 45 to 60, vaginal dryness scores fell by week 12 in the women taking 20, 30 or 50 mg a day of Pueraria mirifica, and their vaginal cells shifted toward a more mature pattern by week 24. The report gives these as changes within the Pueraria group, and only 20 women took placebo. Adverse effects did not differ from placebo.
Menopausal symptom scores
In studies without a placebo group, menopause symptom scores fell by about 40% to 65% over 6 months at 25 to 100 mg a day, and in one comparison the fall was similar to conjugated estrogen. A 2018 systematic review judged the effect inconclusive because placebo response was not controlled and products were not standardized.
Bone turnover marker in postmenopausal women
In the 24-week placebo-controlled trial, bone-specific alkaline phosphatase, a marker of bone turnover, fell from 0.22 to 0.13 U/L with Pueraria mirifica and did not change with placebo, which the authors read as an estrogen-like effect. Bone density and fractures were not measured.
Cholesterol in postmenopausal women
In a 2-month placebo-controlled trial in 19 postmenopausal women, HDL cholesterol rose 34% and LDL cholesterol fell 17% from baseline with Pueraria mirifica. These are changes from baseline in a very small trial. In the larger 24-week trial, triglycerides rose about 15% in both the Pueraria mirifica and placebo groups.
Mechanism of action
Estrogen receptor activation
In cell tests, miroestrol and coumestrol from the root activated both estrogen receptor alpha and beta, while daidzein and genistein mainly activated estrogen receptor beta. This estrogen activity is the proposed basis for the effects on vaginal tissue, bone markers and blood lipids.
Estrogen-like effects on breast and uterine tissue in rats
In female rats, Pueraria mirifica in the diet increased uterine weight, and at 200 mg/kg a day for 36 weeks it raised the rate of chemically induced breast tumors and abnormal growth of the uterine lining. This animal finding is why people with estrogen-sensitive conditions should avoid it.
Bone turnover
Estrogen slows bone turnover. The fall in bone-specific alkaline phosphatase seen with Pueraria mirifica in postmenopausal women is consistent with this estrogen-like action, but it is a lab marker, not a measure of bone strength.
Clinical trials
Randomized, double-blind, placebo-controlled trial of 20, 30 or 50 mg/day Pueraria mirifica capsules for 24 weeks, with lipid, bone marker, endometrial, breast and blood safety tests (Manonai et al. 2008, Menopause).
71 healthy postmenopausal women aged 45 to 60 analyzed (51 on Pueraria mirifica, 20 on placebo).
Triglycerides rose 15% in both the Pueraria mirifica and placebo groups. Bone-specific alkaline phosphatase fell from 0.22 to 0.13 U/L with Pueraria mirifica and stayed at 0.20 U/L with placebo. Endometrial thickness did not change, no endometrial growth was found, and breast, blood, liver and kidney tests did not differ from placebo.
Randomized, double-blind, placebo-controlled trial of 20, 30 or 50 mg/day Pueraria mirifica capsules for 24 weeks, measuring vaginal symptoms, vaginal health index, pH and cell maturation (Manonai et al. 2007, Menopause). It appears to report the same 71 women as the lipid and bone turnover paper above.
71 healthy postmenopausal women aged 45 to 60 analyzed (51 on Pueraria mirifica, 20 on placebo).
In the Pueraria mirifica group, vaginal dryness decreased after 12 weeks and the vaginal maturation index shifted from 46:43:11 to 11:65:24 (parabasal:intermediate:superficial cells) after 24 weeks. Adverse effects did not differ from placebo.
Randomized, double-blind, placebo-controlled trial of oral Pueraria mirifica powder for 2 months, plus cell tests of its plant estrogens (Okamura et al. 2008, Tohoku J Exp Med).
19 postmenopausal women.
Compared with baseline, the Pueraria mirifica group had 34% higher HDL cholesterol, 40% higher apolipoprotein A-1, 17% lower LDL cholesterol and 9% lower apolipoprotein B. Results are reported as changes from baseline in a very small trial.
Open-label phase II study with random assignment to 50 or 100 mg/day Pueraria mirifica for 6 months and no placebo group, scored with the modified Greene climacteric scale (Lamlertkittikul et al. 2004, J Med Assoc Thai).
37 of 48 enrolled perimenopausal women with hot flushes or night sweats were evaluated.
Mean symptom scores fell from 35.6 to 15.1 (50 mg) and from 32.6 to 13.6 (100 mg) over 6 months. A few women had transient anemia or liver test changes. Without a placebo group, the size of the true effect is unknown.