Wild Yam

by MedlinePlus

It has been hypothesized that wild yam (Dioscorea villosa and other dioscorea species) possesses dehydroepiandrosterone (DHEA)-like properties, and acts as a precursor to human sex hormones such as estrogen and progesterone. Based on this proposed mechanism, extracts of the plant have been used to treat dysmenorrhea, hot flashes, and headaches associated with menopause. However, these uses are based on a misconception that wild yam contains hormones or hormonal precursors - largely due to the historical fact that progesterone, androgens, and cortisone were chemically manufactured from Mexican wild yam in the 1960s. It is unlikely that this chemical conversion to progesterone occurs in the human body. The hormonal activity of some topical wild yam preparations has been attributed to adulteration with synthetic progesterone by manufacturers, although there is limited evidence in this area.

The effects of the wild yam saponin constituent "diosgenin" on lipid metabolism are well documented in animal models, and are possibly due to impaired intestinal cholesterol absorption. However, its purported hypocholesterolemic effect in humans and the feasibility of long-term use warrant further investigation.

There are few reported contraindications to the use of wild yam in adults. However, there are no reliable safety or toxicity studies during pregnancy, lactation, or childhood.

Note: "Yams" sold in the supermarket are members of the sweet potato family and are not true yams.

Evidence

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Uses based on scientific evidence

High cholesterol

Animal studies have shown that wild yam can reduce absorption of cholesterol from the gut. Early studies in humans have shown changes in the levels of certain sub-types of cholesterol, including decreases in low-density lipoprotein (LDL, or "bad cholesterol") and triglycerides, and increases in high-density lipoprotein (HDL, or "good cholesterol"). However, no changes in the total amount of blood cholesterol have been found. More studies are needed in this area.

Menopausal symptoms

Most studies have not shown a benefit from wild yam given by mouth or used as a vaginal cream, in reducing menopausal symptoms. However, replacing two thirds of staple food with yam for 30 days was shown to improve the status of sex hormones, lipids, and antioxidants in a recent study in postmenopausal women. The authors suggest that these effects might reduce the risk of breast cancer and cardiovascular diseases in postmenopausal women. Further research is needed before a recommendation can be made.

Hormonal properties (to mimic estrogen, progesterone, or DHEA)

Despite popular belief, no natural progestins, estrogens, or other reproductive hormones are found in wild yam. Its active ingredient, diosgenin, is not converted to hormones in the human body. Artificial progesterone has been added to some wild yam products. The belief that there are hormones in wild yam may be due to the historical fact that progesterone, androgens, and cortisone were chemically manufactured from Mexican wild yam in the 1960s.

Uses based on tradition or theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Antifungal, anti-inflammatory, antiviral, asthma, bile flow improvement, biliary colic, breast cancer, breast enlargement, cancer prevention, cardiovascular disease, childbirth, cramps, croup, decreased perspiration, diverticulitis, expectorant, flatus prevention, energy improvement, excessive perspiration, intestinal spasm, irritable bowel syndrome, joint pain, libido, liver protection, low blood sugar, menopause, menstrual pain or irregularities, morning sickness, nerve pain, osteoporosis, pelvic cramps, pancreatic enzyme inhibitor, postmenopausal vaginal dryness, premenstrual syndrome, rash, spasms, urinary tract disorders, uterus contraction, vomiting.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)

Topical (on the skin):

Cream: Vaginal creams containing wild yam are available, but there is no widely accepted dose. Effects from absorption into the bloodstream have not been shown. Some products may contain synthetic progesterone, a steroid hormone with potential activity in vaginal changes.

Oral (by mouth):

Note: safety and effectiveness of oral doses have not been proven .

Dried root: 2-4 grams or 1-2 teaspoons daily in 2-3 divided doses has been used.

Capsules: 250 milligrams of wild yam taken 1-3 times daily has been used, or 450-900 milligrams per day of dioscorea extract from wild yam.

Liquid(1:1 in 45% alcohol): 2-4 milliliters daily in 3 divided doses has been used.

Tincture: 4-12 drops or 2-4 milliliters taken 3-5 times daily has been used.

Children (younger than 18 years)

Not enough evidence is available to recommend use in children. In unofficial reports, doses in children have been calculated in proportion to the weight of the child relative to a 70 kilogram (150 pound) adult. Divide the child's weight in kilograms by 70 (or weight in pounds by 150); this number multiplied by the recommended adult dose = the child's dose. Safety and effectiveness have not been proven, and dosing should be supervised by a licensed healthcare provider.

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