Wild yam, scientifically known as Dioscorea villosa, is a vine native to North America, Asia, and Africa. It has been used for centuries in traditional medicine for various health benefits.
Here's an overview of its characteristics and uses:
What is Wild Yam?
Wild yam is a perennial vine that can grow up to 9 feet in length. It has heart-shaped leaves and produces clusters of small, greenish-white flowers. The plant's tuberous roots are the most commonly used part for medicinal purposes.
Wild yam can be found growing in various habitats, including forests, woodlands, and along riverbanks, primarily in temperate and tropical regions.
Primary Compounds in Wild Yam
Diosgenin: This steroid sapogenin is the primary active compound in wild yam. It is a precursor to synthetic steroid hormones, and has been shown to boost cognition as discussed below.
Traditional Uses of Wild Yam
Native American Medicine
Indigenous peoples of North America used wild yam for various purposes, including women's health issues, digestive disorders, and pain relief.
Traditional Chinese Medicine
In TCM, wild yam (called Shan Yao) is used to tonify the spleen and stomach, nourish yin, and promote the production of body fluids.
Recognized Benefits of Wild Yam
Menopausal Symptoms Relief
Wild yam is commonly used to alleviate symptoms of menopause, such as hot flashes, mood swings, and vaginal dryness. It contains diosgenin, a compound believed to have estrogen-like effects, although more research is needed to confirm its efficacy for menopausal symptoms.
Anti-inflammatory Properties
Some studies suggest that wild yam may possess anti-inflammatory properties, making it potentially useful for conditions such as arthritis and inflammatory bowel disease.
Digestive Health
In traditional medicine, wild yam has been used to support digestive health, alleviate stomach discomfort, and promote regular bowel movements.
Muscle Relaxant
Wild yam is sometimes used as a natural muscle relaxant to ease muscle cramps and spasms.
Human Clinical Research:
IN a 2023 study from Japan’s Ritsumeikan University, researchers tested 66 people. For 12 weeks they received either a placebo or 2000 milligrams per day of wild yam tablets. All the volunteers did some nominal muscle training. The researchers found that wild yam significantly improved muscle quantity and quality, and improved muscle thickness compared to the placebo group who did the same exercises.
A study from the National Taiwan Normal University tested 24 healthy postmenopausal women for several weeks. They were tested for blood levels of various hormones. The women were given 240 grams of wild yam, and retested for hormone levels.
The researchers found the women’s levels of estrone were 26% higher, estradiol was 27% higher and sex hormone binding globulin (SHBG) was 9.5% higher. They also found urinary levels of the genotoxic metabolite of estrogen, 16alpha-hydroxyestrone was reduced by 37%. “Bad cholesterol levels also went down.
The researchers concluded:
“Although the exact mechanism is not clear, replacing two thirds of staple food with yam for 30 days improves the status of sex hormones, lipids, and antioxidants. These effects might reduce the risk of breast cancer and cardiovascular diseases in postmenopausal women.”
In a 2017 study, researchers from Japan’s University of Toyama tested 28 healthy people between 20 and 81 years old. They were fed wild yam extract in capsules for 12 weeks. After a washout period crossover tests studied all volunteers comparing to a placebo group.
The researchers tested their cognition using the Assessment of Neuropsychological Status (RBANS) test for brain and cognition testing. The researchers found that the wild yam extract significantly increased their scores after the 12 week testing period.
The researchers concluded:
“The diosgenin-rich yam extract treatment appeared to safely enhance cognitive function in healthy adults.”
A 2014 also found an herbal combination containing wild yam significantly improved cognition among Alzheimer’s patients.
In a 2012 study, researchers from China’s Hospital of PLA tested 49 patients with chronic obstructive pulmonary disease (COPD). they were given either a mixture of wild yam or a placebo for one month.
The researchers found the patients receiving the wild yam had significantly better scores on their respiratory tests, including the St. George's respiratory questionnaire (SGRQ) and the BODE index.
After three months of use, the patients continued their improvement in breathing health. They also were able to exercise more. The researchers concluded:
“Chinese yam-epimedium mixture can significantly improve dyspnea, exercise capacity, and the quality of life of patients with stable moderate or severe COPD.”
Researchers from China’s South China University of Technology found in a 2019 study that Diosgenin from wild yam could significantly reduce atherosclerosis.
Multiple laboratory studies have found that wild yam significantly inhibited the growth of human breast cancer cells as well.
How to Consume Wild Yam
The easiest way to consume wild yam is to include it in our regular diet. Wild yams are often available at Farmer's Markets or natural food stores. Otherwise, there are tablets and capsules of wild yam available for daily dosing. Follow the label recommendations and as always, talk your doctor if you believe you have a health condition.
Scientific References
Iemitsu K, Fujie S, Uchida M, Inoue K, Shinohara Y, Iemitsu M. Dioscorea esculenta Intake with Resistance Training Improves Muscle Quantity and Quality in Healthy Middle-Aged and Older Adults: A Randomized Controlled Trial. Nutrients. 2023 May 24;15(11):2438. doi: 10.3390/nu15112438.
Wu WH, Liu LY, Chung CJ, Jou HJ, Wang TA. Estrogenic effect of yam ingestion in healthy postmenopausal women. J Am Coll Nutr. 2005 Aug;24(4):235-43. doi: 10.1080/07315724.2005.10719470.
Tohda C, Yang X, Matsui M, Inada Y, Kadomoto E, Nakada S, Watari H, Shibahara N. Diosgenin-Rich Yam Extract Enhances Cognitive Function: A Placebo-Controlled, Randomized, Double-Blind, Crossover Study of Healthy Adults. Nutrients. 2017 Oct 24;9(10):1160. doi: 10.3390/nu9101160.
Zhao YL, Song HR, Fei JX, Liang Y, Zhang BH, Liu QP, Wang J, Hu P. The effects of Chinese yam-epimedium mixture on respiratory function and quality of life in patients with chronic obstructive pulmonary disease. J Tradit Chin Med. 2012 Jun;32(2):203-7. doi: 10.1016/s0254-6272(13)60012-6.
Sadhu A, Upadhyay P, Agrawal A, Ilango K, Karmakar D, Singh GP, Dubey GP. Management of cognitive determinants in senile dementia of Alzheimer's type: therapeutic potential of a novel polyherbal drug product. Clin Drug Investig. 2014 Dec;34(12):857-69. doi: 10.1007/s40261-014-0235-9.
Aumsuwan P, Khan SI, Khan IA, Avula B, Walker LA, Helferich WG, Katzenellenbogen BS, Dasmahapatra AK. Evaluation of wild yam (Dioscorea villosa) root extract as a potential epigenetic agent in breast cancer cells. In Vitro Cell Dev Biol Anim. 2015 Jan;51(1):59-71. doi: 10.1007/s11626-014-9807-5.
Wu FC, Jiang JG. Effects of diosgenin and its derivatives on atherosclerosis. Food Funct. 2019 Nov 1;10(11):7022-7036. doi: 10.1039/c9fo00749k.
Park MK, Kwon HY, Ahn WS, Bae S, Rhyu MR, Lee Y. Estrogen activities and the cellular effects of natural progesterone from wild yam extract in mcf-7 human breast cancer cells. Am J Chin Med. 2009;37(1):159-67. doi: 10.1142/S0192415X09006746.