Wild yam has not been shown to prevent or treat cancer.
Wild yam contains a compound called diosgenin that mimics estrogen and progesterone in animals. Diosgenin can be converted into active steroid compounds in the lab. Small studies using different species and formulas of wild yam extract have had mixed results on menopausal symptoms. Another small study suggests that increasing yam intake through diet may improve sex hormone and cholesterol levels. A lab study showed that wild yam extract has weak hormonal activity against human breast cancer cells, but this does not mean it can prevent or treat cancer.
More studies are needed to confirm whether wild yam or its extract actually has any benefits. In addition, some animal and lab studies have shown that wild yam extract can cause chronic kidney injury.
Some creams containing wild yam may be promoted as a natural source of progesterone, when it is really synthetic progesterone or comes from other sources. Wild yam itself does not contain progesterone, but diosgenin in wild yam can be used to make progesterone in the lab.
Derived from the root of a twining vine, wild yam was traditionally used for its antispasmodic and anti-inflammatory properties to treat menopausal symptoms, gastrointestinal ailments, muscle spasm, asthma, joint pain, and rheumatoid arthritis (1)(2). Wild yam has antiproliferative (3) and antimitotic effects (4) in vitro, and animal models also suggest it has antinociceptive and anti-inflammatory properties (1). Diosgenin, the active ingredient in wild yam, was shown to have estrogenic and progestogenic effects in mice (3)(5)(6)(7).
Two small studies on whether wild yam can relieve menopausal symptoms had opposing results, with one demonstrating an oral D. alata formula to be more effective than placebo (8), but another study showing a topical D. villosa formula to be ineffective (9). A study of dietary yam was found to improve sex hormone and lipid profiles (10). More studies are needed to confirm whether dietary or supplemental wild yam actually has any benefits for menopausal symptoms.
Wild yam extract is sold as a dietary supplement, liquid extract or as a cream. Diosgenin in wild yam has been used as raw material for synthetic progesterone, but there is no evidence that the human body can convert diosgenin into progesterone.
The steroid saponin diosgenin in wild yam modulates cell signaling involved in growth, differentiation, apoptosis, and oncogenesis (14). In vitro studies suggest wild yam extract protects against human breast cancer proliferation by acting as a weak phytoestrogen (3). However, the D. villosa species has been noted to induce chronic kidney injury via pro-fibrotic pathways in animal models (15).
Patients should be aware that creams containing extracts of wild yam have been promoted as a natural source of progesterone. However, the progesterone contained in these creams is synthetic or derived from other sources.