Plant Comparison
Wild Yam vs Japanese knotweed
A side-by-side comparison of two medicinal plants — every documented constituent, action, use, safety note and cited source, assembled automatically from the Omnia Sana database.
At a glance
Wild Yam and Japanese knotweed: they share 4 indicated uses (arthritis / joint pain, cancer (anticancer research), inflammation (general), …); 2 pharmacological actions in common.
Evidence face-off — shared uses
| Condition | Wild Yam | Japanese knotweed | Verdict |
|---|---|---|---|
| Arthritis / joint pain | 2/10 | 2/10 | Comparable evidence |
| Cancer (anticancer research) | 2/10 | 2/10 | Comparable evidence |
| Inflammation (general) | 2/10 | 7/10 | Stronger for Japanese knotweed |
| Skin irritation | 2/10 | 1/10 | Comparable evidence |
Evidence scores (1–10) are computed from the tier of each cited source. “Comparable” means the two scores are within one point. Follow a score to its detailed sources.
Key Constituents
Diosgenin is an industrial precursor for making steroid hormones in the laboratory, but it is NOT converted into hormones in the human body. Oral bioavailability of diosgenin is low; in animal studies orally administered diosgenin restored skin thickness in ovariectomised mice and lowered blood lipids.
Considered the principal bioactive constituents, responsible for much of the antioxidant, anti-inflammatory and cardioprotective activity attributed to this root.
Emodin has laxative and anti-inflammatory activity at typical concentrations but can cause gastrointestinal upset at high doses.
Pharmacological Actions
Antispasmodic / analgesic for menstrual cramps and muscle spasm (antinociceptive in animal models)
Anti-inflammatory for joint and inflammatory pain
Antispasmodic / analgesic for menstrual cramps and muscle spasm (antinociceptive in animal models)
Traditional & Indicated Uses
inferred from anti-inflammatory action
inferred from anticancer action
inferred from anti-inflammatory action
Traditional support for menopausal symptoms (see safety note - it does NOT act as a natural progesterone) - a placebo-controlled crossover RCT of topical wild yam cream found little effect on menopausal symptoms, lipids or hormones
Antispasmodic / analgesic for menstrual cramps and muscle spasm (antinociceptive in animal models)
Antispasmodic / analgesic for menstrual cramps and muscle spasm (antinociceptive in animal models)
Anti-inflammatory for joint and inflammatory pain
inferred from anti-inflammatory action
inferred from anti-inflammatory action
inferred from anticancer action
inferred from anti-inflammatory action
Safety, Cautions & Contraindications
IMPORTANT myth-bust: wild yam / diosgenin is NOT converted into progesterone or DHEA in the body, so it does not work as a 'natural progesterone' - claims to that effect are incorrect. Consistent with this, a randomized placebo-controlled crossover trial of topical wild yam cream found no significant change in symptoms, serum/salivary progesterone, oestradiol, FSH or lipids.
Generally well tolerated orally (no acute or subchronic toxicity in animal studies); large doses may cause nausea or vomiting. Avoid medicinal doses in pregnancy and breastfeeding and in hormone-sensitive conditions as a precaution.
Japanese knotweed root contains resveratrol and emodin; high doses of emodin may cause GI discomfort and have laxative effects. Not recommended during pregnancy (emodin has potential teratogenic effects in animal studies). May interact with anticoagulants and antiplatelet medications. Quality control of commercial preparations is important as invasive weed extracts vary significantly.
Duke (2002) rates Japanese knotweed (listed as Hu-Zhang, Fallopia japonica) as +++ and highlights its rich content of resveratrol and emodin. Experimental evidence (score 1) supports COX-2 inhibitory, antioxidant, anti-inflammatory, hepatoprotective, and lipid-lowering activities — largely attributed to resveratrol. Duke notes its use in traditional Chinese medicine for fractures, burns, abscesses, and gynecological conditions. No significant clinical trials were available at time of publication, but resveratrol's biological activity is well-documented in vitro (Duke, 2002).
External Ids
Botanical Description
Twining, herbaceous perennial vine with heart-shaped leaves arising from a knotty, woody, cinnamon-brown rhizome ('root'). Small, inconspicuous greenish-yellow flowers are borne on separate male and female plants, followed on female plants by small three-winged seed capsules.[10]
Vigorous, invasive rhizomatous perennial (Polygonaceae) with hollow, bamboo-like, jointed stems 1-3 m tall (occasionally taller), speckled reddish-purple. Leaves are broad, heart- to shovel-shaped with a flat base. Abundant sprays of small, creamy-white flowers appear in late summer, followed by small winged fruit.[6]
Habitat
Native to woodland edges, thickets and fence rows of eastern North America, growing over shrubs and fences in moist, rich soil.[10]
Native to East Asia (Japan, China, Korea), now a notorious invasive species across Europe and North America, growing in disturbed ground, riverbanks, roadsides and waste land, spreading aggressively via an extensive rhizome network.[6]
Harvesting
The knotty rhizome is dug in autumn once the aerial vine has died back, then cleaned and dried.
The rhizome/root, the main medicinal part, is dug in autumn or winter when resveratrol content is highest; young spring shoots (stems) are also edible and used. Strict containment is required when harvesting, given the plant's severe invasiveness.[6]
Traditional Uses
Wild yam root has a Native American and Eclectic-medicine history as an antispasmodic remedy for colic, menstrual cramps and rheumatic joint pain (reflected in the old names 'colic root' and 'rheumatism root'); despite a persistent modern myth, its diosgenin content is not converted into progesterone or other hormones in the human body.[10]
Known as Hu Zhang in Traditional Chinese Medicine, Japanese knotweed root has a centuries-old use for inflammation, infections, jaundice and menstrual complaints. Modern interest centres on its resveratrol and emodin content, now studied (as Polygonum cuspidatum extract) for antioxidant, anti-inflammatory, cardioprotective and hepatoprotective activity, and more recently for supportive use in acute respiratory infections.[2, 3, 6]
Preparations
References
Lookalikes Review
Dosage
Not documented
Duke (2002) and general phytotherapy guidance treat this as an experimentally supported herb without a single agreed clinical dose; commercial resveratrol-standardised extracts should be dosed per product labelling. Educational reference only, not a prescription; avoid in pregnancy.
References & Sources
- Depypere, H.T. and Comhaire, F.H (2013) 'Herbal preparations for the menopause: beyond isoflavones and black cohosh', Maturitas, 77(2), pp. 191-194. doi:10.1016/j.maturitas.2013.11.001 Traditional / reference
https://doi.org/10.1016/j.maturitas.2013.11.001 - Cai, B., Zhang, Y., Wang, Z., Xu, D. et al (2020) 'Therapeutic Potential of Diosgenin and Its Major Derivatives against Neurological Diseases: Recent Advances', Oxidative Medicine and Cellular Longevity, 2020, pp. 3153082. doi:10.1155/2020/3153082 Traditional / reference
https://doi.org/10.1155/2020/3153082 - Raj, P.S., Bergfeld, W.F., Belsito, D.V., Cohen, D.E. et al (2023) 'Safety Assessment of Dioscorea Villosa (Wild Yam) Root Extract as Used in Cosmetics', International Journal of Toxicology, 42(3_suppl), pp. 29S-31S. doi:10.1177/10915818231204230 Traditional / reference
https://doi.org/10.1177/10915818231204230 - Dong, S., Nikolic, D., Simmler, C., Qiu, F., van Breemen, R.B., Soejarto, D.D., Pauli, G.F. and Chen, S (2012) 'Diarylheptanoids from Dioscorea villosa (wild yam)', Journal of Natural Products, 75(12), pp. 2168-2177. doi:10.1021/np300603z Preclinical
https://doi.org/10.1021/np300603z - Dong, S., Cai, G., Napolitano, J.G., Nikolic, D., Lankin, D.C., McAlpine, J.B., van Breemen, R.B., Soejarto, D.D., Pauli, G.F. and Chen, S (2013) 'Lipidated steroid saponins from Dioscorea villosa (wild yam)', Fitoterapia, 91, pp. 113-124. doi:10.1016/j.fitote.2013.07.018 Preclinical
https://doi.org/10.1016/j.fitote.2013.07.018 - Wojcikowski, K., Wohlmuth, H., Johnson, D.W. and Gobe, G (2008) 'Dioscorea villosa (wild yam) induces chronic kidney injury via pro-fibrotic pathways', Food and Chemical Toxicology, 46(9), pp. 3122-3131. doi:10.1016/j.fct.2008.06.090 Preclinical
https://doi.org/10.1016/j.fct.2008.06.090 - Mazzio, E., Almalki, A., Darling-Reed, S.F. and Soliman, K.F.A (2021) 'Effects of wild yam root (Dioscorea villosa) extract on the gene expression profile of triple-negative breast cancer cells', Cancer Genomics & Proteomics, 18(6), pp. 735-755. doi:10.21873/cgp.20294 Preclinical
https://doi.org/10.21873/cgp.20294 - Ali, Z., Smillie, T.J. and Khan, I.A (2013) 'Cholestane steroid glycosides from the rhizomes of Dioscorea villosa (wild yam)', Carbohydrate Research, 370, pp. 86-91. doi:10.1016/j.carres.2012.12.022 Preclinical
https://doi.org/10.1016/j.carres.2012.12.022 - Manda, V.K., Avula, B., Ali, Z., Wong, Y., Smillie, T.J., Khan, I.A. and Khan, S.I (2013) 'Characterization of in vitro ADME properties of diosgenin and dioscin from Dioscorea villosa', Planta Medica, 79(15), pp. 1421-1428. doi:10.1055/s-0033-1350699 Preclinical
https://doi.org/10.1055/s-0033-1350699 - Lima, C.M., Lima, A.K., Melo, M.G.D., Serafini, M.R., Oliveira, D.L., de Almeida, E.B., Barreto, R.S.S., Nogueira, P.C., Moraes, V.R.S., Oliveira, E.R.A., de Albuquerque, R.L.C., Quintans-Junior, L.J. and Araujo, A.A.S (2013) 'Bioassay-guided evaluation of Dioscorea villosa - an acute and subchronic toxicity, antinociceptive and anti-inflammatory approach', BMC Complementary and Alternative Medicine. doi:10.1186/1472-6882-13-195 Preclinical
https://doi.org/10.1186/1472-6882-13-195 - Avula, B., Wang, Y., Wang, M., Ali, Z., Smillie, T.J., Zweigenbaum, J. and Khan, I.A (2014) 'Characterization of steroidal saponins from Dioscorea villosa and D. cayenensis using ultrahigh performance liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry', Planta Medica, 80(4), pp. 321-329. doi:10.1055/s-0033-1360330 Preclinical
https://doi.org/10.1055/s-0033-1360330 - Siddiqui, M.A., Ali, Z., Chittiboyina, A.G. and Khan, I.A (2018) 'Hepatoprotective effect of steroidal glycosides from Dioscorea villosa on hydrogen peroxide-induced hepatotoxicity in HepG2 cells', Frontiers in Pharmacology, 9, pp. 797. doi:10.3389/fphar.2018.00797 Preclinical
https://doi.org/10.3389/fphar.2018.00797 - Hayes, P.Y., Lambert, L.K., Lehmann, R., Penman, K., Kitching, W. and De Voss, J.J (2007) 'Complete 1H and 13C assignments of the four major saponins from Dioscorea villosa (wild yam)', Magnetic Resonance in Chemistry, 45(11), pp. 1001-1005. doi:10.1002/mrc.2071 Preclinical
https://doi.org/10.1002/mrc.2071 - Okawara, M. and Tokudome, Y. and Todo, H. and Sugibayashi, K. and Hashimoto, F (2013) 'Enhancement of diosgenin distribution in the skin by cyclodextrin complexation following oral administration', Biological & Pharmaceutical Bulletin, 36(1), pp. 36--40. doi:10.1248/bpb.b12-00467 Preclinical
https://doi.org/10.1248/bpb.b12-00467 - Komesaroff, P.A., Black, C.V., Cable, V. and Sudhir, K (2001) 'Effects of wild yam extract on menopausal symptoms, lipids and sex hormones in healthy menopausal women', Climacteric, 4(2), pp. 144--150. doi:10.1080/cmt.4.2.144.150 Randomized trial
https://doi.org/10.1080/cmt.4.2.144.150
- Dong, X., Fu, J., Yin, X., Cao, S. and others (2016) 'Emodin: A Review of its Pharmacology, Toxicity and Pharmacokinetics', Phytotherapy Research, 30(8), pp. 1207-1218. doi:10.1002/ptr.5631 Traditional / reference
https://doi.org/10.1002/ptr.5631 - Wang, S., Yang, Y., Sun, L., Qiao, G. and others (2022) 'Reynoutria japonica Houtt for Acute Respiratory Tract Infections in Adults and Children: A Systematic Review', Frontiers in Pharmacology, 13, pp. 787032. doi:10.3389/fphar.2022.787032 Meta-analysis / review
https://doi.org/10.3389/fphar.2022.787032 - Ke, Y., Zhan, L., Lu, T., Zhou, C. and others (2023) 'Advances for pharmacological activities of Polygonum cuspidatum (Reynoutria japonica) - A review', Pharmaceutical Biology, 61(1), pp. 177-188. doi:10.1080/13880209.2022.2158349 Traditional / reference
https://doi.org/10.1080/13880209.2022.2158349 - Zhang, Q., Zhao, Y., Zhang, M., Zhang, Y. and others (2021) 'Bioactive amides from Reynoutria japonica', Journal of Asian Natural Products Research, 23(3), pp. 228-234. doi:10.1080/10286020.2021.1873298 Preclinical
https://doi.org/10.1080/10286020.2021.1873298 - Lai, Y., Zhou, C., Huang, P., Dong, Z. and others (2024) 'Polygonum cuspidatum polysaccharide: A review of its extraction and purification, structure analysis, and biological activity', Journal of Ethnopharmacology, 331, pp. 118079. doi:10.1016/j.jep.2024.118079 Traditional / reference
https://doi.org/10.1016/j.jep.2024.118079 - Peng, W., Qin, R., Li, X. and Zhou, H (2013) 'Botany, phytochemistry, pharmacology, and potential application of Polygonum cuspidatum Sieb. et Zucc.: a review', Journal of Ethnopharmacology, 148(3), pp. 729-745. doi:10.1016/j.jep.2013.05.007 Traditional / reference
https://doi.org/10.1016/j.jep.2013.05.007 - Wang, X., Liang, L., Yan, J., Li, Z. and others (2023) 'Citri Reticulatae Pericarpium-Reynoutria japonica Houtt. herb pair suppresses breast cancer liver metastasis by targeting ECM1-mediated cholesterol biosynthesis pathway', Phytomedicine, 116, pp. 154896. doi:10.1016/j.phymed.2023.154896 Preclinical
https://doi.org/10.1016/j.phymed.2023.154896 - Jiang, Y., Liu, Y., Zhang, X. and others (2020) 'New phenolic glycosides from Reynoutria japonica', Journal of Asian Natural Products Research, 22(1), pp. 17-23. doi:10.1080/10286020.2019.1646730 Preclinical
https://doi.org/10.1080/10286020.2019.1646730 - Liu, Y., Wang, J., Li, Q. and others (2024) 'The Possibility of Polygonum cuspidatum against Osteoarthritis based on Network Pharmacology', Current Computer-Aided Drug Design, 20(2), pp. 121-133. doi:10.2174/1573409919666230403114131 Preclinical
https://doi.org/10.2174/1573409919666230403114131 - Espinosa-Andrews, H., Morales-Hernandez, N., Garcia-Marquez, E. and others (2025) 'Physicochemical and rheological characteristics of commercial Greek-style yogurt enriched with Polygonum cuspidatum roots or the P. cuspidatum beta-cyclodextrin inclusion complex', Food Research International, 203, pp. 115854. doi:10.1016/j.foodres.2025.115854 Preclinical
https://doi.org/10.1016/j.foodres.2025.115854 - Burns, J., Yokota, T., Ashihara, H., Lean, M.E.J. and Crozier, A (2002) 'Plant foods and herbal sources of resveratrol', 50(11), pp. 3337--3340. doi:10.1021/jf0112973 Traditional / reference
https://doi.org/10.1021/jf0112973 - Royal Botanic Gardens, Kew (n.d.). Available at: https://powo.science.kew.org Traditional / reference
https://powo.science.kew.org - World Health Organization (2007) 'WHO Monographs on Selected Medicinal Plants'. Traditional / reference
https://scholar.google.com/scholar?q=WHO%20Monographs%20on%20Selected%20Medicinal%20Plants - Duke, J.A (2002) 'Handbook of Medicinal Herbs, Second Edition'. Traditional / reference
https://scholar.google.com/scholar?q=Handbook%20of%20Medicinal%20Herbs%2C%20Second%20Edition
Generated automatically from the Omnia Sana plant database and its cited sources. For educational purposes only — not medical advice. Always consult a qualified practitioner before using medicinal plants.