Traditionally used for
- Headaches
- Dizziness
- Colds & fever
- Digestion
- Blood pressure
Cautions & contraindications
- Bleeding disorders
☯ TCM Properties
Calms the Liver, descends Liver Yang and nourishes Yin to extinguish internal Wind; Enriches Kidney Yin, reduces Deficiency fever, and stops nightsweats; Clears Heat and relieves toxicity
Traditional Chinese Uses
This entry corresponds to the seed coat of the black soybean, Glycine max (Hei Dou Yi, Testa Glycinis). Sweet and neutral, entering the Liver, Heart and Stomach (and Kidney) channels, it nourishes Yin and Blood and calms the Liver, subduing ascendant Liver Yang to settle internal Wind. It is taken for dizziness, vertigo and headache from Liver Yang rising or Yin-Blood deficiency, and enriches Kidney/Liver Yin to reduce Deficiency-fever and night sweats. It also clears Heat and mildly resolves toxicity.
Gentle in action, it is used as a supporting herb in decoctions for hypertension-type dizziness and steaming-bone Deficiency Heat, often combined with Yin-nourishing and Liver-calming herbs. The whole black soybean (Hei Dou) itself more strongly tonifies the Kidneys and nourishes the Blood.
Relationships
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Botanical Description
Glycine max, the soybean, is an erect to suberect annual herb of the Fabaceae family domesticated in East Asia for several millennia and now the world's most important leguminous crop. The plant typically grows fifty to one hundred fifty centimeters tall with a branching stem clothed in stiff brown or grey hairs. Leaves are alternate, pinnately trifoliolate with broadly ovate to elliptic leaflets, the lateral pair usually larger than the terminal; stipules and stipels are present. Small white, pink, or pale purple papilionaceous flowers are borne in short axillary racemes during summer, self-pollinated, and quickly give way to densely pubescent pods two to seven centimeters long, each containing one to four nearly spherical to ellipsoid seeds. The black-seeded varieties known in Chinese as Hei Dou are the type used for the medicinal preparation.
Active Constituents
Anthocyanins (cyanidin-3-O-glucoside and related delphinidin/petunidin glucosides)
Anthocyanins (flavonoid pigments)Concentration: ≈ 2.3–14.4 mg per g in the seed coat; >99% concentrated in the testa
The pigments responsible for the black seed coat and its potent antioxidant, anti-inflammatory and vasoprotective activity; the principal actives of the seed coat (Hei Dou Yi), consistent with its traditional use to nourish yin, extinguish wind and calm the liver.
Isoflavones (daidzein, genistein, glycitein)
Isoflavones (phytoestrogens)Concentration: ≈ 795–4195 µg per g in black soybean
Phytoestrogens with antioxidant and endothelial effects; daidzein and genistein stimulate endothelial nitric-oxide release and inhibit ACE, mechanisms relevant to the herb's use for liver-yang rising and hypertension-type patterns.
Soy storage protein
Protein / amino acidsConcentration: ≈ 30–40% of the seed by weight
High-quality plant protein; the nutritive basis of black soybean's tonifying dietary role and a source of bioactive peptides.
Flavan-3-ols and phenolic acids
PolyphenolsConcentration: Enriched in brown/black seed coats
Contribute substantially to the seed coat's radical-scavenging capacity alongside anthocyanins, supporting its antioxidant and anti-aging activity.
Saponins (soyasaponins)
Triterpenoid saponinsConcentration: Minor constituents
Have antioxidant, lipid-lowering and hepatoprotective properties documented for soybean, contributing to the metabolic benefits attributed to black soybean.
Tocopherols and lutein
Lipophilic antioxidantsConcentration: Minor constituents of the seed
Vitamin-E-type and carotenoid antioxidants that protect lipids from oxidation and complement the water-soluble anthocyanin/isoflavone antioxidants.
⚠ Drug Interactions
Warfarin
Soy isoflavones may modulate CYP2C9-mediated warfarin metabolism, and soy products (especially fermented ones) can contribute vitamin K that antagonises warfarin; case reports describe reduced anticoagulant effect.
Clinical note: Keep soy intake consistent and monitor INR when using black soybean regularly with warfarin.
Levothyroxine
Soy protein and isoflavones can impair intestinal absorption of oral levothyroxine, potentially lowering circulating thyroid hormone; clinical impact appears modest but is well documented.
Clinical note: Separate black soybean intake from levothyroxine by at least 4 hours and monitor thyroid function.
Tamoxifen
Genistein and other isoflavones are phytoestrogens; preclinical data suggest high isoflavone exposure may stimulate estrogen-receptor-positive tumour cells and could interfere with tamoxifen's action.
Clinical note: Patients with hormone-sensitive breast cancer on tamoxifen should discuss concentrated soy/isoflavone intake with their oncologist; culinary amounts are generally considered acceptable.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 9–30 g | Daily | — | — | 中国药典 2020 monograph 【黑豆】【用法与用量】9～30g。外用适量，煎汤洗患处。 【性味与归经】甘，平。归脾、肾经。 — Matched to ChP by romanised drug name (pinyin 'Hei Dou' → 黑豆); the romanisation is unique across all 649 ChP monographs, and the match was cross-checked against this record's own TCM temperature. Quoted verbatim. |
Preparation Methods
Decoction of the seed coat (Hei Dou Yi)
Parts: Black soybean seed coat (testa)
The dried black seed coat (about 6–12 g) is decocted in water and taken to nourish yin, cool the blood, calm liver-yang and stop night sweats and dizziness.
Decoction / dietary use of whole black soybean
Parts: Whole ripe black seed
Whole black soybeans (9–30 g) are decocted or cooked into congee and soups as a tonic to strengthen the spleen and kidneys, promote urination and resolve toxicity; also processed with other herbs to make prepared soybean (Dan Dou Chi).
Evidence Tier
Moderate evidence · 1 studyRecorded studies by study design, strongest design at the top. This is a study-design tier only, not a GRADE rating: it does not weigh risk of bias, consistency or precision.
Systematic review / meta-analysis
0
Randomized controlled trial
1
1 verified · 0 unverified
Other clinical trial
0
Observational / case report
0
In vitro / animal
0
Other / unclassified
0
Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description
Clinical Studies
Effect of whole soy and purified daidzein on ambulatory blood pressure and endothelial function—a 6-month double-blind, randomized controlled trial among Chinese postmenopausal women with prehypertension
In equol-producing postmenopausal women with prehypertension or untreated hypertension, neither whole soy nor purified daidzein produced a significant effect on ambulatory blood pressure or endothelial function over 6 months, indicating limited antihypertensive benefit of soy isoflavones in this population.
⚠ Safety & Contraindications
- Bleeding disorders
Contraindications
Patients with deficiency-cold of constitution should not use it for a long-term.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, pp. 73–79.
Historical Texts
Shen Nong Ben Cao Jing (Divine Husbandman's Classic of Materia Medica)
Han dynasty, c. 1st–2nd century CEBen Cao Gang Mu (Compendium of Materia Medica), Li Shizhen
Ming dynasty, 1578References
- Ganesan K, Xu B. A critical review on polyphenols and health benefits of black soybeans . Nutrients 9(5):455 (2017) [DOI]
- Liu ZM, Ho SC, Chen YM, et al.. Effect of whole soy and purified daidzein on ambulatory blood pressure and endothelial function (RCT) . European Journal of Clinical Nutrition 69(10):1161-1168 (2015) [DOI]
- Bensky D, Clavey S, Stöger E. Chinese Herbal Medicine: Materia Medica, 3rd edition . Eastland Press, Seattle (2004) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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