Chi Xiao Dou
StarVigna umbellata (Thunb.) Ohwi et Ohashi
Traditionally used for
- Urinary & fluids
- Skin
- Liver & jaundice
☯ TCM Properties
Promotes Urination and Reduces Edema; Clears Damp-Heat and Resolves Jaundice; Resolves Toxicity and Expels Pus; Invigorates Blood and Dispels Stasis
Traditional Chinese Uses
Chi Xiao Dou (adzuki bean) is a mild, sweet, food-grade herb used in Chinese medicine to drain Dampness, reduce edema, and clear Heat. It addresses swelling of the lower limbs, mild jaundice from Damp-Heat, and skin infections such as boils and abscesses. As both a medicine and a common food, its regular consumption in soups and desserts has long been part of East Asian dietary therapy for fluid management and mild internal cleansing.
Relationships
Full-screen graph →Click a node for details · double-click to expand it · Ctrl/⌘ + scroll or two fingers to zoom and pan.
Botanical Description
Vigna umbellata, the rice bean, is an annual to short-lived perennial twining legume in the family Fabaceae, native to tropical and subtropical Asia and cultivated as a minor pulse crop and green manure across India, China, southeast Asia, and parts of Africa. The plant produces slender, soft-hairy, twining or trailing stems 1-3 m long from a slender taproot. The alternate leaves are pinnately trifoliolate with ovate to ovate-rhombic leaflets 4-10 cm long, the terminal one symmetrical and the lateral ones often somewhat lobed at the base, all sparsely hairy. Bright yellow papilionaceous flowers about 1.5 cm long are borne in short, dense, axillary racemes on long peduncles, the keel petals strongly twisted. The fruit is a slender, cylindrical, slightly curved pod 6-12 cm long that ripens from green to brown and contains 6-12 small, oblong, somewhat compressed seeds, commonly red, but also yellow, brown, or mottled depending on the cultivar.
Active Constituents
Vitexin and isovitexin
Flavone C-glycosidesConcentration: Two of eight phenolics quantified by UPLC-MS across 13 Chinese rice bean varieties; the eight together range 123.09 to 843.75 micrograms per gram of seed
Characteristic C-glycosidic flavones of the rice bean seed and part of what distinguishes its phenolic fingerprint from the adzuki bean. They contribute to the seed's antioxidant capacity and to inhibition of advanced glycation end-product formation.
Catechin and epicatechin
Flavan-3-olsConcentration: Present in both the free and the alkali-released bound phenolic fractions; catechin is abundant in both
The phenolics most responsible for the antioxidant activity of the seed. Bound phenolics released by base hydrolysis account for about 71 percent of total phenolic content, so most of the seed's polyphenol is only liberated during digestion or cooking, not by simple extraction.
Isoquercitrin, rutin and taxifolin
Flavonol glycosides and dihydroflavonolConcentration: Among the main monomeric phenolics of the free fraction; 35 individual phenolics identified in total
Principal free-fraction flavonoids of the rice bean seed, contributing radical-scavenging activity.
Procyanidin B1
Proanthocyanidin (condensed tannin)Concentration: A main monomeric-fraction phenolic of the free extract
Oligomeric flavan-3-ol contributing to the astringency and antioxidant capacity of the seed coat.
p-Coumaric, ferulic and sinapic acids
Hydroxycinnamic acidsConcentration: Quantified among the eight major phenolics of the seed
Cell-wall-bound phenolic acids of the seed; largely esterified and released only on alkaline or digestive hydrolysis.
Gallic acid, protocatechuic acid and p-hydroxybenzoic acid
Hydroxybenzoic acidsConcentration: Main monomeric phenolics of the bound fraction, which totals 14.18 mg gallic acid equivalents per gram of dry seed after base hydrolysis
Dominate the bound phenolic fraction and carry most of its superior antioxidant capacity; they are the fraction a decoction is most likely to mobilise.
⚠ Drug Interactions
Vigna angularis (adzuki bean, Chi Dou) supplied in place of Vigna umbellata
Chi Xiao Dou is routinely supplied as Vigna angularis rather than Vigna umbellata, and Chinese pharmacopoeial practice has accepted both species under the one name, so this is a sanctioned substitution rather than a covert adulteration. It still matters for evidence: the two published Vigna umbellata studies of any depth are in vitro phenolic and enzyme-inhibition work, while the animal pharmacology commonly quoted for Chi Xiao Dou (atopic-dermatitis-like skin inflammation, osteoarthritis and osteoporosis models, antihypertensive and renal work) was all done on Vigna angularis. The seeds are also distinguishable in the crude drug: authentic Vigna umbellata is narrower, more elongated, darker purplish-red and has a raised white hilum, whereas Vigna angularis is shorter, rounder, brighter red-brown with a flat hilum.
Clinical note: Specify the binomial, not just the pinyin, when ordering, and inspect the seed shape and hilum. When quoting research to a patient, name the species the study used; do not present adzuki-bean animal data as evidence for rice bean.
Acarbose and other alpha-glucosidase inhibitors; insulin and sulfonylureas
Extracts of 13 Chinese Vigna umbellata varieties inhibited alpha-glucosidase by 44.3 to 68.7 percent in vitro, the same enzyme target as acarbose, and inhibited advanced glycation end-product formation by 34 to 76 percent. This is a cell-free enzyme assay, not a human study, and the effect at culinary or decoction doses is unknown; the bean is also a substantial carbohydrate source in its own right.
Clinical note: No dose adjustment is warranted on this evidence, but if a patient on insulin or a sulfonylurea takes large daily amounts of the bean as food as well as medicine, treat it as a dietary change and check glucose.
Loop and thiazide diuretics
The entire basis for the herb's diuretic reputation is traditional. No controlled diuresis study of Vigna umbellata in humans or animals was found, and the traditional dose is large (9-30 g, sometimes more). The concern is additive volume and potassium loss during a prescribed diuretic course, not a documented pharmacological interaction.
Clinical note: Where a patient on a loop or thiazide diuretic takes Chi Xiao Dou in large doses for oedema, check electrolytes as you would for any added diuretic pressure, and do not assume the herb is inert simply because it is also a food.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction, or powder/pills | 9–30 g | Daily | — | — | 中国药典 2020 【用法与用量】9～30g。外用适量，研末调敷。 【性味与归经】甘、酸，平。归心、小肠经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
Dui Yao — Herb Pairs
The classical two-herb combinations this herb appears in, each with an action neither herb has alone.
Drains damp-heat and resolves toxicity while harmonizing blood, treating damp-heat with blood stasis in the lower body.
Bleeding hemorrhoids or intestinal abscess with damp-heat.
Core pair of a classical formula — Chi Xiao Dou Dang Gui San, Jin Gui Yao Lue (Zhang Zhongjing)
Bitter emetic action combined with the sour-sweet bean, which together induce vomiting to expel phlegm or food lodged in the chest and upper stomach.
Phlegm or undigested food obstructing the chest in robust patients. Gua Di is toxic; discontinue once vomiting occurs; contraindicated in weak patients, the elderly and pregnancy.
Core pair of a classical formula — Gua Di San, Shang Han Lun (Zhang Zhongjing)
Evidence Tier
Moderate evidence · 4 studiesRecorded 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
0
Other clinical trial
0
Observational / case report
0
In vitro / animal
4
1 verified · 3 unverified
Show 4 studies
- Major Phenolic Compounds, Antioxidant Capacity and Antidiabetic Potential of Rice Bean (Vigna umbellata L.) in China
- Profiles of Free and Bound Phenolics and Their Antioxidant Capacity in Rice Bean (Vigna umbellata)
- Effects of Vigna angularis extract and its active compound hemiphloin against atopic dermatitis-like skin inflammation
- Beneficial effects of Vigna angularis extract in osteoporosis and osteoarthritis
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
Major Phenolic Compounds, Antioxidant Capacity and Antidiabetic Potential of Rice Bean (Vigna umbellata L.) in China
The first phytochemical and bioactivity survey of the actual medicinal species. Thirteen Chinese rice bean varieties were profiled for eight phenolics by UPLC-MS; total phenolic compounds ranged 123.09 to 843.75 micrograms per gram, alpha-glucosidase inhibition 44.3 to 68.7 percent and inhibition of advanced glycation end-product formation 34.1 to 75.8 percent. Cell-free enzyme assays only, with no animal or human subjects.
Profiles of Free and Bound Phenolics and Their Antioxidant Capacity in Rice Bean (Vigna umbellata)
Thirty-five phenolics were identified in Vigna umbellata. Bound phenolics released by base hydrolysis reached 14.18 mg gallic acid equivalents per gram and accounted for 71.15 percent of total phenolic content, with higher antioxidant capacity than the free fraction. The practical implication is that most of the seed's polyphenol is not extracted by water or methanol alone.
Effects of Vigna angularis extract and its active compound hemiphloin against atopic dermatitis-like skin inflammation
Used Vigna angularis, the substituted species, not Vigna umbellata. A 70 percent ethanol extract reduced ear thickness and IgE in DNCB-induced skin inflammation in mice and suppressed IL-1beta, IL-6, IL-8, CCL17 and CCL22 in TNF-alpha/IFN-gamma-stimulated HaCaT keratinocytes; the flavone hemiphloin reproduced the effect. Cite it for adzuki bean, not for rice bean.
Beneficial effects of Vigna angularis extract in osteoporosis and osteoarthritis
Again Vigna angularis rather than Vigna umbellata. Extract administration reduced cartilage damage in monosodium iodoacetate-induced osteoarthritis and restored bone mineral content and density in ovariectomised rats. Animal models only, and outside the traditional indications of Chi Xiao Dou.
⚠ Safety & Contraindications
Contraindications
Its use is cautious in patients with yin deficiency and fluid consumption.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, p. 144.
Historical Texts
Shen Nong Ben Cao Jing (Divine Husbandman's Classic of Materia Medica)
Han dynasty, c. 200 CEShang Han Lun (Treatise on Cold Damage), Zhang Zhongjing
Late Han dynasty, c. 200-220 CEJin Gui Yao Lue (Essentials from the Golden Cabinet), Zhang Zhongjing
Late Han dynasty, c. 200-220 CEReferences
- Ahmed S, Shakeel N, Alsharif KF, Alzahrani KJ, Aschner M, Daglia M, Farag MA, Khan H. Unlocking the potential of rice bean (Vigna umbellata): Emerging source of bioactives for future foods and food security . Journal of Food Composition and Analysis (2026) [DOI]
- Katoch R. Nutritional Potential of Rice Bean (Vigna Umbellata): An Underutilized Legume . Journal of Food Science (2013) [DOI]
- Takahama U, Yamauchi R, Hirota S. Isolation and characterization of a cyanidin-catechin pigment from adzuki bean (Vigna angularis) . Food Chemistry (2013) [DOI]
- Sato S, Mukai Y, Yamate J. Beneficial Effects of Azuki Bean (Vigna angularis) Extract: Anti-Oxidant, Anti-Hypertension, and Treatment for Renal Damage . Current Nutrition & Food Science (2009) [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.
📝 Notes
Public notes from the community and your own private notes on Chi Xiao Dou.
No notes yet.