Dao Dou
StarCanavalia gladiata (Jacq.) DC.
Traditionally used for
- Digestion
- Pain & joints
- Energy & fatigue
☯ TCM Properties
Warms the Middle Burner; Descends Qi; Directs Rebellious Qi Downward and Stops Hiccup; Tonifies Kidney Yang; Protects the Stomach
Traditional Chinese Uses
Dao Dou (jack bean, canavalia seed) is a warm herb used in Chinese medicine to warm the middle burner and descend rebellious Qi, addressing hiccup and belching from Stomach cold or Kidney Yang deficiency failing to hold Qi in its proper place. It also tonifies Kidney Yang for lower back and knee weakness and kidney-related fatigue. Its combined Qi-descending and Kidney-warming action makes it specifically useful where hiccup or belching arises from cold deficiency of the lower burner rather than from excess heat.
Western Herbalism Properties
Relationships
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Botanical Description
Canavalia gladiata, the sword bean or Dao Dou, is a vigorous, twining, herbaceous to slightly woody perennial legume in the Fabaceae, often cultivated as an annual. The stems climb 3 to 10 meters by means of long, smooth, twining shoots. Leaves are alternate and pinnately trifoliate, with broadly ovate to elliptic leaflets 8 to 20 cm long, glabrous or with sparse hairs, and acuminate at the tip. Flowers are borne in axillary, long-peduncled racemes of large, papilionaceous, pink to purplish or white flowers about 3 to 4 cm long. The pod is the most distinctive feature: very large, flattened, slightly curved and sword-shaped, 15 to 35 cm long and 3 to 5 cm wide, with a prominent longitudinal ridge along the upper suture and a leathery, green to pale-yellow wall. Each pod contains 8 to 16 large, oblong, smooth seeds with a long, conspicuous hilum, varying from white through pink to deep red. Native to tropical Asia, it is widely cultivated for food and medicine.
Active Constituents
L-Canavanine
Non-protein amino acid (L-arginine analogue)Concentration: described as the predominant amino acid of the mature seed; overnight soaking followed by boiling in excess water and decanting removes roughly 50%, boiling and decanting alone about 34%, while roasting and autoclaving are much less effective (Ekanayake et al., 2007)
Canavanine is charged by arginyl-tRNA synthetase in place of L-arginine, so it is misincorporated into protein to give structurally aberrant canavanyl proteins, and it also interferes with arginine-dependent enzymes. It is the constituent that makes raw or undercooked sword bean toxic, and the compound implicated in the lupus-like syndrome produced by alfalfa. Practically, this means the traditional insistence on thorough cooking is a genuine detoxification step, not a culinary preference.
Canavalia gladiata seed lectin (concanavalin A-like lectin)
Legume lectin (mannose/glucose-specific)Concentration: a major seed protein; subunits of roughly 25-30 kDa, highly homologous to but not identical with concanavalin A of Canavalia ensiformis
Worth stating precisely, because concanavalin A is routinely attributed to this species: concanavalin A proper comes from Canavalia ensiformis, the jack bean, while Canavalia gladiata, the sword bean, has its own closely homologous lectin whose crystal structure was solved separately and which differs from concanavalin A in mitogenic and antiproliferative behaviour. The lectin agglutinates erythrocytes and is antiproliferative to tumour cell lines in vitro; it is denatured by adequate boiling.
Canavalin
7S vicilin-type storage globulinConcentration: one of the two principal storage proteins of the seed alongside concanavalin
A nutritional storage protein rather than a pharmacologically active one; it contributes to the seed's high protein content and to its trypsin-inhibitor and allergenic load before cooking.
Urease
Nickel metalloenzymeConcentration: present in the raw seed; inactivated by heat
Canavalia ureases are the classical source of the enzyme and are counted among the antinutritional factors of the raw seed. Heat inactivation during decoction removes them.
Seed oil fatty acids
Unsaturated fatty acidsConcentration: linoleic acid 58.33%, palmitoleic acid 16.2% and linolenic acid 12.98% of Chinese seed oil; South Indian material 69.1-81.8% unsaturated against 18.2-30.9% saturated
Nutritional rather than therapeutic; relevant mainly because it explains the seed's tendency to go rancid on prolonged storage.
⚠ Drug Interactions
Immunosuppressants and disease-modifying drugs in systemic lupus erythematosus (hydroxychloroquine, azathioprine, mycophenolate, corticosteroids)
L-canavanine sulfate reactivated a systemic lupus erythematosus-like syndrome in cynomolgus macaques in which the syndrome had previously been induced by alfalfa seeds or sprouts (Malinow et al., 1982), and case reports describe exacerbation of human SLE with alfalfa ingestion. That work used alfalfa, Medicago sativa, not Canavalia gladiata; the connection is that canavanine is the implicated agent and the sword bean seed is a rich source of it. No case of sword-bean-triggered lupus has been published.
Clinical note: Avoid Dao Dou in patients with SLE or another canavanine-sensitive autoimmune condition, and be aware that thorough soaking and boiling only halves the canavanine content rather than eliminating it.
L-arginine supplements and arginine-dependent therapies
Canavanine is a close structural analogue of arginine, competes with it for arginyl-tRNA synthetase and for arginine-metabolising enzymes, and is an inhibitor of inducible nitric oxide synthase in experimental systems. Co-administration with arginine loading would be expected to reduce canavanine incorporation, and conversely a canavanine-rich decoction may blunt an intended arginine effect. This is inference from the biochemistry, not from a clinical study.
Clinical note: No action needed at ordinary decoction doses; note it if a patient is on high-dose arginine for a specific indication.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 6–9 g | Daily | — | — | 中国药典 2020 【用法与用量】6～9g。 【性味与归经】甘，温。归胃、肾经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
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
2 verified · 2 unverified
Show 4 studies
- Canavanine content in sword beans (Canavalia gladiata): Analysis and effect of processing
- Systemic Lupus Erythematosus-Like Syndrome in Monkeys Fed Alfalfa Sprouts: Role of a Nonprotein Amino Acid
- Identification of Interleukin (IL)-33 Inhibitory Constituents from Canavalia gladiata Pods
- Inhibitory Effect of Canavalia gladiata Extract on Aggregatibacter actinomycetemcomitans LPS Induced Nitric Oxide in Macrophages
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
Canavanine content in sword beans (Canavalia gladiata): Analysis and effect of processing
Developed and validated a reversed-phase HPLC method for canavanine as its dabsyl derivative (recovery 88-91%) and applied it to raw and processed sword beans. Overnight soaking followed by boiling in excess water and decanting gave the greatest reduction in canavanine, around 50%; boiling and decanting alone gave 34%; roasting and autoclaving were less effective. This is the quantitative basis for insisting on soak-boil-discard preparation of Dao Dou.
Systemic Lupus Erythematosus-Like Syndrome in Monkeys Fed Alfalfa Sprouts: Role of a Nonprotein Amino Acid
Cynomolgus macaques fed alfalfa seeds or sprouts developed haematological and serological abnormalities resembling human SLE, and dietary L-canavanine sulfate alone reactivated the syndrome in previously affected animals. The species studied was Medicago sativa, not Canavalia gladiata, but it is the primary evidence that canavanine as such can drive autoimmunity, and canavanine is the sword bean's chief toxic constituent.
Identification of Interleukin (IL)-33 Inhibitory Constituents from Canavalia gladiata Pods
Isolated constituents from Canavalia gladiata and screened them for inhibition of IL-33, an alarmin cytokine in allergic inflammation. The material studied was the pod wall, not the seed that constitutes the drug Dao Dou, so the findings do not transfer directly to the seed monograph.
Inhibitory Effect of Canavalia gladiata Extract on Aggregatibacter actinomycetemcomitans LPS Induced Nitric Oxide in Macrophages
Canavalia gladiata extract suppressed nitric oxide production in macrophages stimulated with lipopolysaccharide from the periodontal pathogen Aggregatibacter actinomycetemcomitans, supporting an anti-inflammatory action in cell culture. Macrophage-line work only; no animal or human data.
⚠ Safety & Contraindications
Contraindications
Its use is cautious in patients with intense stomach heat.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, pp. 171–182.
Historical Texts
Ben Cao Gang Mu
Ming dynastyReferences
- Qian H, Meng D, Yue L, Xu H, Feng K, Wang J. Ethnobotanical Use, Phytochemistry, Pharmacology, and Toxicity of Canavalia gladiata . Drug Design, Development and Therapy (2025) [DOI]
- Delatorre P, Rocha BAM, Souza EP, Oliveira TM, Bezerra GA, Moreno FBMB, Freitas BT, Santi-Gadelha T, Sampaio AH, Azevedo WF, Cavada BS. Structure of a lectin from Canavalia gladiata seeds: new structural insights for old molecules . BMC Structural Biology (2007) [DOI]
- Schlüter M, Bordas E. Canavanine in Canavalia paraguayensis, C. gladiata and Dioclea paraguayensis . Phytochemistry (1972) [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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