Yam: Benefits, Dosage, Contraindications
Other name(s)
Wild yam, Chinese yam
Scientific name(s)
Dioscorea oppositifolia, Dioscorea villosa
Family or group:
Plants
Active ingredients:
Diosgenin
Dioscorine
Indications
Rating methodology
EFSA approval.
Menopause ✪✪✪✪✪
Diosgenin, the saponin extracted from yam, does not bind to human estrogen or progesterone receptors in vitro and cannot be converted to progesterone in the human body. Yam could theoretically be administered to women treated for breast cancer, but safety data are needed. When administered as a cream, the effect on menopause symptoms is not statistically significant compared to placebo. A study in which 22 women received 390 g of Chinese yam per day for 30 days revealed that urinary concentrations of the genotoxic estrogen metabolite, 16-alpha-hydroxyestrone, decreased significantly by 37%, suggesting a potential to reduce breast cancer risk, but again, clinical trial data are needed. Another study on menopausal Taiwanese women concluded that the Diascorea alata variety significantly reduced psychological symptoms, particularly anxiety, after 12 months of consumption.
Posologie
Oral: root, rhizome
50 - 390 mg
12 - months
Standardized extract, dry extract
Estrogenic Effects of the Extracts From the Chinese Yam (Dioscorea Opposite Thunb.) and Its Effective Compounds in Vitro and in Vivo
Effects of wild yam extract on menopausal symptoms, lipids and sex hormones in healthy menopausal women.
Comparative Analysis of Proteins With Stimulating Activity on Ovarian Estradiol Biosynthesis From Four Different Dioscorea Species in Vitro Using Both Phenotypic and Target-based Approaches: Implication for Treating Menopause
Research and Development of Proteins and Peptides With Therapeutic Potential From Yam Tubers
Estrogenic Effect of Yam Ingestion in Healthy Postmenopausal Women
Cognitive Performance ✪✪✪✪✪
Preliminary clinical research shows that taking a specific wild yam extract at 50 mg per day for 12 weeks slightly improves overall cognitive function and semantic fluency measures compared to placebo in healthy adults.
Posologie
Oral: root, rhizome
50 - 250 mg
12 - weeks
Standardized extract, dry extract
Aging Gracefully ✪✪✪✪✪
The steroidal saponins found in yam may exert estrogenic effects and combat symptoms related to the decrease in estrogen levels due to aging. Several studies have described the pharmacological effects of diosgenin and its derivatives against various diseases such as cancer, diabetes, osteoporosis, Alzheimer's disease, and strokes. Increasing experimental evidence has shown that diosgenin and its derivatives present promising therapeutic potential in several neurodegenerative and neurological disorders.
Posologie
Oral administration: root, rhizome
50 - 250 mg
standardized extract, dry extract
Osteoporosis ✪✪✪✪✪
Due to its estrogenic activity, yam may be beneficial in cases of osteoporosis. It has been found that yam increased bone mineral density in ovariectomized rats, but studies in humans are lacking.
Posologie
Oral administration: root, rhizome
50 - 250 mg
standardized extract
Diarrhea ✪✪✪✪✪
Huai Shan Yao (Chinese yam), a common staple in China, has been used for over 2000 years in TCM to treat various systemic diseases. It is also used to strengthen stomach functions, relieve anorexia, and cure diarrhea.
Posologie
Oral administration: root, rhizome
50 - 250 mg
powder
Properties
Estrogenic Action
Chemical conversion of diosgenin, a constituent of wild yam, into estrogen, progesterone, or other steroid compounds would not occur in the human body. However, wild yam seems to have some estrogenic properties, although these properties vary by species. A wild yam extract enhances estradiol binding to estrogen receptors and induces transcriptional activity in estrogen-sensitive cells. Laboratory research evaluating four Dioscorea species, including D. oppositifolia (Chinese yam), D. alata, D. collettii var. hypoglaucau, and D. zingiberensis, found that only Dioscorea oppositifolia exhibits estrogenic effects on ovarian cells. In animal research, Dioscorea oppositifolia extract increases estradiol and follicle-stimulating hormone (FSH) levels, regulates estrogen receptor expression in the uterus. Adenosine and arbutin are thought to be responsible for these estrogenic effects. Menopausal women replacing 390 grams daily of wild yam (Dioscorea alata) with another staple food such as rice for 30 days show significant increases in serum estrone, sex hormone-binding globulin (SHBG), and possibly serum estradiol levels.
Usages associés
Hormonal Metabolism
One of the steroidal saponins, diosgenin, has been isolated from wild yam. Diosgenin has been commercially used to produce steroid hormones such as cortisone, estrogen, and progesterone by chemical modification in vitro. Although it was hypothesized that wild yam extract might convert to DHEA (De Hydro Epi Androsterone) in humans, this has not been demonstrated in humans. A small clinical study showed that no steroidogenesis results in increased DHEA or cholesterol by diosgenin. Chemical conversion of diosgenin, a constituent of wild yam, into estrogen, progesterone, or other steroid compounds would not occur in the human body. However, wild yam seems to have some estrogenic properties, although these properties vary by species. A wild yam extract enhances estradiol binding to estrogen receptors and induces transcriptional activity in estrogen-sensitive cells. In animal research, Dioscorea oppositifolia extract increases estradiol and follicle-stimulating hormone (FSH) levels, regulates estrogen receptor expression in the uterus. Adenosine and arbutin are thought to be responsible for these estrogenic effects.
Usages associés
Anticancer
Components of Chinese yam have shown tumoricidal activity on certain cancer cell lines, including breast cancer MCF7 cells, hepatoma HepG2 cells, nasopharyngeal carcinoma CNE2 cells, and melanoma B16 cancer cell lines. In a comparative in vitro study, wild yam root (Dioscorea villosa) was found to be the plant extract with the most potent tumoricidal activity, ahead of 374 other plant extracts.
Neurological
In animal studies, diosgenin, a constituent of yam, improves memory deficits and object recognition memory. In early clinical research, a wild yam extract standardized to diosgenin slightly improved cognitive function in healthy adults. Many studies have demonstrated that diosgenin and its derivatives have preventive and therapeutic effects against various neurological disorders. Animal experiments have shown diosgenin is active in treating nervous system diseases such as Parkinson's and Alzheimer's.
Usages associés
Gastroprotective
The 40% ethanol extract of Chinese yam has shown the ability to inhibit gastric acid secretion and improve intestinal functions, observed through gastrointestinal transit and the presence of lactose-fermenting bacteria in stools. Chinese yam seems to positively influence the composition of the intestinal flora. Studies on rats have revealed that consuming yam powder fermented by Lactobacillus acidophilus reduces gastric lesions. Furthermore, yam fermented with Lactobacillus bulgaricus has shown increased protection against gastric lesions, suggesting its usefulness in yogurt production.
Cholagogue
Studies suggest wild yam, particularly its diosgenin component, could have a beneficial effect on bile. Diosgenin increases cholesterol secretion in bile and prevents estrogen-induced reduction of bile flow in rats. It also aids in the elimination of indomethacin and reduces the intestinal inflammation it may cause.
Safety dosage
Adult from 18 years: 50 mg - 390 mg (standardized extract)
- Decoction of dried root: 2-4 g three times a day. - Tincture (1:5): 2-10 ml three times a day.
Interactions
Médicaments
Estrogens: moderate interaction
Yam having estrogenic properties, its concomitant use with estrogens could generate additional effects.
Precautions
Hormone-sensitive disease: avoid
In vitro evidence suggests that wild yam has estrogenic and anti-estrogenic effects; however, it does not appear to affect hormone levels when used topically. Women with hormone-sensitive conditions should avoid wild yam. Hormone-sensitive conditions include breast cancer, uterine cancer, ovarian cancer, endometriosis, and uterine fibroids
Protein S deficiency: avoid
Patients with protein S deficiency have an increased risk of thrombosis. Wild yam could increase the risk of thrombosis in these patients due to the potential estrogenic activity of wild yam.
Pregnant woman: avoid
Not enough data.
Breastfeeding woman: avoid
Not enough data.
