Dioscorea villosa L. · herb
Evidence tier: insufficient
A traditional cramping herb. Note: it does NOT convert to progesterone in the body, common misconception.
There is no established mechanism in humans, and stating one is where this ingredient goes wrong. Diosgenin is a steroidal sapogenin and a chemical FEEDSTOCK for the industrial synthesis of progesterone and other steroids; it is not a precursor the body can use, and MSK states there is no evidence the human body converts it into progesterone. What laboratory work does show is that diosgenin modulates cell signalling involved in growth, differentiation and apoptosis, and that wild yam extract has weak phytoestrogenic activity in vitro. That is a cell culture observation, not a hormonal effect demonstrated in a person, and it is not a basis for a progesterone or hormone balance claim.
Insufficient, and the reason is the most instructive fact in this batch: the central premise of the entire wild yam market is false. Memorial Sloan Kettering states it in one sentence with no hedge: there is no evidence that the human body can convert diosgenin into progesterone. The confusion has a real history, which is why it is so durable. In the 1940s Russell Marker worked out how to synthesise progesterone from diosgenin in a LABORATORY, which collapsed the cost of steroid hormones and made the contraceptive pill possible. That is a multi step chemical process performed in a reaction vessel. The human body does not have that pathway. It cannot run those steps. Consequently every product marketed as natural progesterone from wild yam is either mislabelled or has had actual synthetic progesterone added to it, and creams that genuinely contain nothing but yam extract deliver no hormone at all. The clinical evidence matches the chemistry. MSK summarises the whole literature as limited mixed evidence on whether wild yam might be helpful for menopausal symptoms: one trial of an oral formula beat placebo, another found a topical formula ineffective, and MSK's own verdict is that larger investigations are needed. There is no trial support for the hormone balance claim, no trial support for progesterone deficiency, and only traditional use, Mexican and Native American, for cramping. That traditional use is real and is all that can honestly be said. Safety is not a free pass either. MSK notes that Dioscorea villosa has been shown to induce chronic kidney injury via profibrotic pathways in animal models, and flags that its weak phytoestrogen activity means people with hormone sensitive cancers should speak to a physician before using it. An absent LiverTox chapter is not a clearance, and neither is a thin adverse event record for a herb almost nobody takes in a measured dose.
Tea or tincture: 1 to 2 g daily for digestive or menstrual cramping.
Avoid in pregnancy. Generally well tolerated otherwise.
Pregnancy: avoid
Breastfeeding: caution
Active compounds: diosgenin, dioscin, steroidal saponins
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*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.