For the record, the estrogen from pregnant mares used for hormone replacement (Premarin) is natural, although it is not identical to the estrogens produced in the human body. Results from the recently terminated Women's Health Initiative study of estrogen replacement therapy (ERT) showed that post-menopausal women who take estrogen face an increased risk of strokes and, possibly, dementia. An earlier study of hormone replacement therapy (HRT), which combines estrogen with another hormone, progestin, was ended early, too, because data showed increased risks of breast cancer, heart disease and strokes among the women participating.
I've never supported universal hormone replacement for peri- or post-menopausal women, but some women do need reliable short-term relief from frequent and intense hot flashes, vaginal dryness that makes sex uncomfortable, or overwhelming fatigue and mood changes associated with menopause. ERT or HRT are the most effective treatments. Now that we know more about the risks involved, hormone replacement is recommended only for treatment of severe menopausal symptoms or for osteoporosis prevention in women at high risk who can't take any of the other medications available to maintain or enhance bone strength.
Wild yam, a tuber of a tropical plant that is unrelated to sweet potatoes, contains a precursor of steroid hormones called diosgenin. However, diosgenin itself has no hormonal activity, and the body can't convert it into something that does. For these reasons, the only possible effect wild yam products can have is a sedative one (when ingested) that can help relieve premenstrual problems. Some of the wild yam creams may contain synthetic progesterone even though this doesn't show up on the label.
Don't waste money on wild yam products.
Andrew Weil, M.D.