WILD YAM
Botanical name: Dioscorea villosa
Synonyms: Colic root, rheumatism root
MAJOR CHEMICAL CONSTITUENTS
Glycoside and steroidal saponins, including diosgenin and dioscin, alkaloids, tannins, phytosterols, and starch
TRADITIONAL AND HISTORICAL USES
Wild yam was used by Native Americans and Eclectic physicians for a wide variety of complaints relating to spasmodic contractions of the hollow viscera ranging from bilious colic to dysmenorrhea. It was included in the National Formulary (NF) from 1916 to 1942 as a diaphoretic and expectorant. In the past decade it has enjoyed a resurgence in popularity based on the erroneous assumption that because it contains steroidal saponins used in the manufacture of progesterone for oral contraceptive pills (OCPs), it could be taken as an herb to increase progesterone levels and thus treat a variety of gynecologic complaints. It is found in topical creams for vaginal dryness. Any increase in progesterone associated with using topical creams, was due to the inclusion of USP grade synthetic progesterone to these products. Its alleged hormonal activity has also led to the inclusion of this herb in breast-enhancing products.
CLINICAL INDICATIONS
Wild yam is reported by herbal practitioners to be a reliable spasmolytic herb in the treatment uterine cramping, dysmenorrhea, chronic pelvic pain (CPP), urinary tract infection (UTI) and interstitial cystitis, particularly as an adjunct in combination with other herbs specific to those complaints. It is also sometimes used by midwives as an antiemetic in the treatment of troublesome nausea and vomiting of pregnancy (NVP) and hyperemesis gravidarum, and as an antispasmodic for irritable uterus or threatened miscarriage with uterine contractions. It is also occasionally used as an adjunct antispasmodic herb painful labor with dysfunctional uterine contractions and in the postpartum period for afterbirth pains.
There is a paucity of studies on the clinical effects of wild yam, and no studies evaluating antispasmodic activity were identified.
IN VITRO, ANIMAL, AND CLINICAL DATA
A 2001 double-blind placebo-controlled crossover study of the effects of a wild yam cream in 23 healthy women suffering from troublesome symptoms of menopause was conducted. After a 4-week baseline period, each woman was given active cream and matching placebo for 3 months in random order. Diaries were completed over the baseline period and for 1 week each month thereafter, and blood and saliva samples were collected at baseline and at 3 and 6 months, for measurement of lipids and hormones. The average age of the subjects was 53.3 *** 1.1 years and average time since last period 4.3 *** 0.9 years. At baseline, the average body mass index was 27.3 *** 0.8, cholesterol level 5.7 *** 0.2 mmol/L and follicle stimulating hormone (FSH) level 74.2 5.1 IU/L; estradiol levels were undetectable in the majority of cases. After 3 months of treatment, no significant side effects were reported with either active treatment or placebo, and there were no changes in weight, systolic or diastolic blood pressure, or levels of total serum cholesterol, triglyceride, high-density lipoprotein (HDL) cholesterol, FSH, glucose, estradiol, or serum or salivary progesterone. Symptom scores showed a minor effect of both placebo and active treatment on diurnal flushing number and severity and total non-flushing symptom scores, and on nocturnal sweating after placebo, but no statistical difference between placebo and active creams. A randomized, controlled trial of 13 menopausal women given two capsules three times daily for 3 months of an herbal combination containing wild yam root in doses lower than recommended, along with burdock root (Arctium lappa), licorice root (Glycyrrhiza glabra), motherwort (Leonurus cardiaca), and angelica root (Angelica archangelica) demonstrated statistically nonsignificant decreases in menopausal symptoms in the active treatment group. Diosgenin, a component of wild yam, has been shown in several studies to reduce total serum cholesterol levels, likely as a result of reduced intestinal cholesterol and an effect potentiated by taking the herb with vitamin C. No hormonal effects, including no changes in DHEA, estrogen, and progesterone levels, or FSH or LH levels, have been observed. In one study of ovariectomized mice receiving 20 to 40 mg/kg of diosgenin injected subcutaneously daily for 15 days, mammary gland epithelial stimulation was observed without progesteronic effects, however, the effects of oral wild yam on breast tissue have not been studied in animal or human trials.
Is Eating Yams Where the Where the Health Benefits for Women Occur?
Interestingly, in a study by Wu et al, 24 apparently healthy postmenopausal women were recruited to replace their staple food (rice for the most part) with 390 g of yam (Dioscorea alata) in two of three meals per day for 30 days and 22 completed the study. Fasting blood and first morning urine samples were collected before and after yam intervention for the analyses of blood lipids, sex hormones, urinary estrogen metabolites and oxidant stress biomarker. The design was a one arm, pre-post study. A similar study of postmenopausal women (n = 19) fed 240 g of sweet potato for 41 days was included as a control study. Serum levels of estrone, estradiol, and SHBG were analyzed for this control group. After yam ingestion, there were significant increases in serum concentrations of estrone (26%), sex hormone-binding globulin (SHBG) (9.5%), and near significant increase in estradiol (27%). No significant changes were observed in serum concentrations of dehydroepiandrosterone sulfate, androstenedione, testosterone, follicular stimulating hormone, and luteinizing hormone. Free androgen index estimated from the ratio of serum concentrations of total testosterone to SHBG decreased. Urinary concentrations of the genotoxic metabolite of estrogen, 16-hydroxyestrone decreased significantly by 37%. Plasma cholesterol concentration decreased significantly by 5.9%. The researchers concluded that ingestion of yams as a staple part of the diet might reduce the risk of breast cancer and cardiovascular diseases in postmenopausal women. This is quite different than using wild yam as an herbal supplement, but nonetheless, worthy of further research. And as yams are such a nourishing food, unless one is on a diabetic diet, they are a healthy inclusion in most diets.
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