Sword bean

Other Names

AbaiAbayAsisimbiAsphotahBadi semBara semBroad beanCanavalia ensiformis var. alba MakinoCanavalia ensiformis var. gladiata (Jacq.) KuntzeCanavalia foureiri G.DonCanavalia gladiata (Jacq.) DC.Canavalia gladiata f. alba (Makino) H.OhashiCanavalia gladiata f. erythrocarpa Taub.Canavalia gladiata var. alba (Makino) HisautiCanavalia gladiata var. cylindrica (DC.) PiperCanavalia gladiata var. erythrosperma VoigtCanavalia gladiata var. machaeroides DC.Canavalia gladiolata J.D.SauerCanavalia incurva (Thunb.) DC.Canavalia incurva ThouarsCanavalia loureiroi G.DonCanavalia lunareti CarrièreCanavalia machaeroides (DC.) Steud.Canavalia maxima ThouarsCarabanzChamma kayaChopdiCryptophaseolus anamensis KuntzeDao douDolic en sabreDolichos gladiatus Jacq.Dolichos incurvus Thunb.Dolique sabreFava-contraFeijão de porcoFûl hindîHaba de burroHalasandeHaricot sabreJamaican horse beanJapanese jackbeanKamtal urahiKattuppayaruKhadsambiKhadsampalMahasimbiMak thoua phaMakhan semMakhan shimMakkhan semMalocchia gladiata (Jacq.) SaviMbwandaMwingasiafuNata mamePatagonian beanPois de l'IndePois sabrePois sabre de la JamaïquePois sabre rougePoroto sableSambeSchwertbohneScimitar beanSegapputampattaiSembiShambiShampeSword jackbeanTammaTammi kayaTebiTumbekontiValamaraValaringhaValavaraik-kayValavaran-gaiValpayar

Synopsis

Sword Bean (Canavalia gladiata): A Comprehensive Reference

1. Identity and Botanical Classification

Scientific Name and Taxonomy

Sword bean belongs to the family Fabaceae, subfamily Faboideae, genus Canavalia, and is classified as the species Canavalia gladiata (Jacq.) DC. It is a domesticated plant species in the legume family Fabaceae, known both as sword bean and scimitar bean. Sword beans were originally described as Dolichos gladiatus by Jacquin in 1788; in 1825, Augustin-Pyrame de Candolle transferred the species to the genus Canavalia.

The genus name Canavalia is derived from the Tupi-Guarani word meaning "green bean," while the species epithet gladiata comes from the Latin word gladius, meaning sword, referring to the shape of its pods. The term "sword bean" is also sometimes applied to the closely related jack bean (Canavalia ensiformis), with which it is occasionally confused. The two species can be distinguished by the length of the hilum (seed scar), which is nearly as long as the seed in the sword bean, and less than half the seed's length in the jack bean.

Morphology

Sword beans are a climbing, herbaceous vine that can reach lengths of up to 10 meters (33 ft) under optimal conditions. The inflorescence is a raceme bearing 10 to 20 flowers, which are either white or light purple, each measuring approximately 3 cm (1.2 in) in length. The fruits are long, straight, slightly compressed pods measuring 20–40 cm (8–16 in), up to 60 cm (24 in), with a rough surface; each pod contains 8 to 16 seeds that are oblong-ellipsoid and variable in color, ranging from red and red-brown to white or black. The seeds of sword bean are typically reddish-pink or light brown, distinguishing them from the white or light-tan seeds of jack bean.

Geographic Origin and Distribution

Canavalia gladiata is believed to have originated from the Old World, probably in eastern Asia, where domestication likely started; today, sword beans remain widely distributed in those regions and are most commonly cultivated in south, southeast, and east Asia, and are also common in Saudi Arabia, East Africa, South Africa, and Madagascar. A tropical perennial legume, it is mainly cultivated as an annual.

Common Names and Forms

The plant is known by numerous vernacular names across its range of cultivation. In Traditional Chinese Medicine (TCM), the plant has significant ethnobotanical value and is referred to as Dao Dou. In Korea and Japan, the seeds and pods of C. gladiata have been used as a coffee substitute. It is used as a vegetable in interior central and south-central India, though not commercially farmed; the unripe pods are also eaten as a vegetable in Africa and Asia.

Common commercial and traditional preparations include:

Fresh vegetables made from the immature fruits, which are tender, crispy, and thick-meated in flavour.
Mature fruits harvested, seeds stripped and dried, then crushed before use — the standard TCM preparation method.
Decoction of 9–15 g, or the seeds stir-baked and ground into powder, as described in traditional Chinese pharmacopeial sources.
Roasted seed extracts, including water-extracted concentrates used in experimental fermented preparations.

2. Traditional and Historical Use

Traditional Chinese Medicine (TCM)

In Traditional Chinese Medicine, C. gladiata has been used for a long history to treat hiccups, vomiting, nausea, amenorrhea, chronic dysentery, larynx arthralgia, lumbago, and inflammatory diseases across Asia. In the TCM framework, Dao Dou is described as having a mild effect to descend rebellious Stomach qi to relieve hiccups, nausea, and vomiting that have deficiency and cold of the Stomach at their root; other associated symptoms include respiratory difficulties, poor appetite, pale complexion, fatigue, and cold extremities.

According to TCM characterization, the herb is sweet and warm in nature, entering the spleen, stomach, large intestine, and kidney meridians; its actions are described as warming the spleen and stomach, directing qi downward, tonifying the kidney, and stopping hiccup; indications include vomiting, stomachache, deficiency of the kidney, lumbago, and deficiency-cold hiccup. Ancient texts also describe their application in soothing coughs, treating toothaches, and supporting spleen and stomach function.

Indian Traditional Medicine

The mature seeds of Canavalia gladiata were originally consumed by people of ancient India and are consumed even by the urbanized population today. In Indian traditional medicine, C. gladiata is used for cold, vomiting, abdominal swelling, lower back pain, asthma with sputum, as an appetizer, and for vitiated conditions of kapha and Pitta.

Korean and Japanese Folk Medicine

In folk medicine in Korea and Japan, C. gladiata has been employed to treat suppurative inflammatory conditions such as sinusitis, hemorrhoids, and boils; its anticancer and antidiabetic activities have also been reported in these traditions. It has been used in traditional medicine to treat suppurative inflammatory conditions, and its antibacterial activity against oral pathogens and potential use as a non-alcoholic mouthwash have also been reported.

Africa and Southeast Asia

The unripe pods have long been eaten as a vegetable across Africa and Asia. The seeds of Canavalia gladiata are also consumed by people living in rural areas of East Timor, though these preparations require precautions due to the presence of toxic compounds, needing to be boiled in multiple changes of water.

Agricultural and Ecological Uses

In addition to food and medicine, the sword bean has been used extensively as a green manure and cover crop. The plant is widely spread in South India's Eastern and Western Ghats and is also used as a fodder crop in Northern and Peninsular India.

3. Key Constituents and Active Compounds

Overall Phytochemical Complexity

Based on published research, more than 231 components have been identified in C. gladiata, including flavonoids, terpenes, steroids, organic acids, nitrogenous compounds, amino acids, and proteins. Phytochemical screening consistently shows a high concentration of polar secondary metabolites, especially concentrated in methanol and ethyl acetate seed extracts; the main classes described include phenolic chemicals, flavonoids, tannins, saponins, and several glycosides (including cardiac glycosides).

Gallotannins and Phenolic Acids

The red sword bean (Canavalia gladiata) has been found to have the highest content of antioxidant polyphenols among 42 edible beans, with gallic acid and gallotannins being the principal constituents in the red bean coat — an apparently unique characteristic among edible beans. Gallotannins of red sword bean coats are mainly comprised of monogalloyl to hexagalloyl hexosides. Both the soluble and bound fractions of black and red sword bean are rich in gallic acid and ellagic acid. The total flavonoid content of C. gladiata has been reported to be significantly higher than that of soybean, highlighting its potential as a high-value functional food source.

A study of seed extracts measured specific polyphenol levels: quantitative analysis revealed that methanol extract had the highest total polyphenolic contents (17.74 ± 1.929 mg of gallic acid equivalents/g DM) and total tannin contents (49.94 ± 1.94 mg of tannic acid equivalents/g DM), while hexane extract had the highest total flavonoid contents (9.06 ± 1.197 mg of quercetin equivalents/g DM).

Canavanine

A non-protein amino acid, canavanine, is present in mature seeds; it is considered the predominant amino acid and has been shown to exhibit specific toxic and antitumor activity. Canavalia gladiata contains toxic antimetabolites including canavanine and its primary metabolite canaline; the content of canavanine has been quantitatively estimated and reported to vary from 2.8 to 4.1% in different processed seeds.

L-Canavanine (CAN) is a non-protein amino acid possessing toxic properties in both animal and plant systems; as an arginine structural analogue, it is typically incorporated into proteins by arginyl-tRNA synthetase, leading to rapid functional disruption of such "canavanyl proteins." CAN is produced in many legumes and accumulates mainly in seeds and newly germinating sprouts; its toxicity has been associated with autoimmunological diseases in humans or animals feeding on plants containing this compound.

Lectins: Concanavalin A and Canavalin

Ripe seeds notably contain antinutritional substances including canavanine, urease, concanavalin A and B, and canavalin. Lectins are proteins or glycoproteins that bind reversibly to specific monosaccharides or oligosaccharides; the seeds of the genus Canavalia, including C. gladiata, show the presence of lectins, and their content and extractability at different pH values differ among species; it has been suggested that lectins could be used as chemotaxonomic markers within the genus.

A lectin isolated from Japanese red sword bean (RSB lectin) shows specificity to mannose, glucose, maltose, methyl-d-mannoside, and thyroglobulin; it exhibits similarities to Concanavalin A in amino acid composition and sequence, shows mitogenic activity for mouse splenic cells, and demonstrates strong antiproliferative activity for B16 melanoma cells, as well as enhancing the activity of splenic natural killer (NK) cells against YAC-1 cells.

Flavonoid Glycosides and Diterpenes

A novel 5-deoxyflavonol named gladiatin has been reported from Canavalia gladiata (Dinda B, Banik R. Chem Nat Compd. 2014;49(6):1001–1002). Researchers have also identified the absolute stereostructures of canavalioside (a new ent-kaurane-type diterpene glycoside) and gladiatosides A1, A2, A3, B1, B2, B3, C1, and C2 (new acylated flavonol glycosides) from the seeds of sword bean (Chem Pharm Bull. 2000;48(11):1673–1680).

4-O-Methylgallic Acid

4-O-methylgallic acid, isolated from the seed of Canavalia gladiata, is a compound with potential as an antiangiogenic agent.

Amino Acid Profile

The seeds possess a range of essential and non-essential amino acids, including lysine (Lys), phenylalanine (Phe), threonine (Thr), alanine (Ala), arginine (Arg), aspartic acid (Asp), and glutamic acid (Glu). Several studies have highlighted the predominance of leucine as the essential amino acid, and aspartic acid and glutamic acid as the dominant non-essential amino acids in seeds.

4. Scientific Evidence by Area of Use

4.1 Antioxidant Activity

Gallotannins and gallotannin-rich extracts have been reported to possess antioxidant, antibacterial, antiproliferative, cardiovascular protective, hepatoprotective, and anti-diabetic activities. The antioxidant potential of sword bean has been demonstrated primarily through in vitro screening. Gallotannin-rich fractions from red sword bean coats have been tested for FRAP (Ferric Reducing Antioxidant Power) and ABTS antioxidant activities, demonstrating notable radical-scavenging capacity.

Evidence strength: Antioxidant effects are supported by multiple in vitro studies. No controlled human trials evaluating antioxidant endpoints from sword bean supplementation have been identified in the peer-reviewed literature.

4.2 Anti-Inflammatory Activity

C. gladiata has been demonstrated to have anti-inflammatory properties using several in vitro assays, including egg albumin denaturation, heat-induced and hypotonicity-induced red blood cell membrane stabilization, as well as hyaluronidase inhibitory activity methods.

A 2026 study published in the journal Fermentation evaluated the anti-inflammatory potential of sword bean extract: this study evaluated sword bean extract (CG) and its Lacticaseibacillus paracasei SKH 003-fermented derivative (CGF) in LPS-stimulated RAW 264.7 macrophages; cells were treated with CG or CGF (0–400 µg/mL) with or without LPS; both CG and CGF significantly attenuated LPS-induced inflammatory responses; the extracts reduced nitric oxide (NO) and prostaglandin E2 (PGE2) production, suppressed mRNA expression of iNOS, COX-2, TNF-α, IL-6, IL-1β, MCP-1, and CXCL10, and upregulated IL-1Ra. Notably, the fermented extract showed broader and stronger suppressive effects on most pro-inflammatory mediators than unfermented extract.

Previous studies have also reported that sword bean extracts suppress inflammatory mediators in LPS-stimulated RAW 264.7 macrophages and alleviate DSS-induced colitis in mice; immature sword bean pod extract has also been shown to inhibit LPS-induced inflammatory responses in RAW264.7 cells.

Evidence strength: Anti-inflammatory effects are well-replicated in cell culture (in vitro) systems and some animal models (particularly colitis models). No published randomized controlled trials or clinical studies in humans have been identified that test anti-inflammatory endpoints directly attributable to sword bean or its extracts.

4.3 Oral Health and Periodontal Disease

A published study aimed to elucidate the biological activity of Concanavalin A from C. gladiata, evaluate nitric oxide production induced by Aggregatibacter actinomycetemcomitans — a key periodontal pathogen — and assess its potential association with periodontal inflammation. CGENa treatment significantly inhibited LPS-induced NO production at concentrations below 6.25 μg/mL without cytotoxic effects, suggesting anti-inflammatory potential associated with lectin-like components. The results suggest that C. gladiata extract suppresses LPS-A. actinomycetemcomitans-mediated macrophage activation; however, further studies are required to determine whether Con A specifically mediates this response and to evaluate its therapeutic relevance in the context of periodontal inflammation.

It has additionally been found that a 50% ethanol extract and canavanine effectively reduced Porphyromonas gingivalis-induced alveolar bone resorption and prevented the growth of P. gingivalis and Fusobacterium nucleatum; however, the potential for antimicrobial activity in vivo still requires investigation despite the seed crude extracts demonstrating antimicrobial efficacy in vitro.

Evidence strength: Preliminary, based on cell culture and in vitro microbiological studies. Clinical human evidence in periodontal disease is lacking.

4.4 Antitumor / Antiproliferative Activity

Bioactive compounds of Canavalia gladiata have been studied for hemagglutinating activity, HIV-1 inhibition, antimicrobial, antiproliferative, hepatoprotective, ROS-inhibitory, anticancer, and antidiabetic properties. The lectin fraction has attracted particular interest: RSB lectin (from Japanese red sword bean) shows strong antiproliferative activity for B16 melanoma cells and enhances the activity of splenic natural killer (NK) cells against YAC-1 cells.

Canavanine has been shown to exhibit specific antitumor activity. The mechanism relates to its structural mimicry of arginine: when used as an anticancer agent, canavanine's mode of action appears to be associated with the synthesis of non-functional proteins in sensitive organisms.

Evidence strength: Antitumor effects are demonstrated in cell lines and some animal model experiments. There are no completed human clinical trials evaluating sword bean preparations for any cancer indication. All cancer-relevant evidence remains preclinical.

4.5 Antidiabetic Activity

Crude extracts, fractions, and constituents from C. gladiata have been reported to show antidiabetic activity, among other pharmacological properties. Emerging data have also highlighted the plant stem's anti-diabetic potential as a significant new therapeutic pathway.

Evidence strength: Antidiabetic evidence is largely based on in vitro and limited animal model studies. No human clinical trials have been identified.

4.6 Hepatoprotective Activity

Biological functions reported for Canavalia gladiata include hepatoprotective activity, in addition to anti-inflammatory, hematopoietic-improving, and anti-angiogenic activities. C. gladiata exhibits strong antioxidant properties, and ethanol extracts have demonstrated anti-inflammatory effects in dextran sulfate sodium (DSS)-induced colitis models.

Evidence strength: Hepatoprotective activity is reported from in vitro and in vivo animal studies only. No human trial data are available.

4.7 Anti-Obesity Activity

Immature sword bean pods have been shown to inhibit adipogenesis in C3H10T1/2 cells and in mice with high-fat diet–induced obesity.

Evidence strength: This finding is from in vitro and mouse model studies only. Human evidence is absent.

4.8 Hematopoietic Activity

Recent studies have shown that sword bean has physiological activities including improved hematopoietic dilatation. Research on this area has been conducted in experimental models, with one Korean study investigating hematopoietic expansion and function of stem cells using Canavalia gladiata DC seed preparations.

Evidence strength: Preclinical, derived from cell-based and animal studies. Human data are lacking.

4.9 Bone and Osteoblast Differentiation

A 2023 study published in the journal Nutrients (PMC10610144) investigated effects on osteoblast differentiation: sword bean contains various phytochemicals, such as flavonoids, tannins, saponins, and terpenoids; its potential functions have been widely reported, including antioxidant, anti-obesity, anti-inflammatory, liver protection, and antiangiogenic activities; however, research on its use in osteoporosis prevention remains insufficient. The study showed that sword bean pod extracts increase osteoblast proliferation, mineralization-activated alkaline phosphatase (ALP), and collagen synthesis activities; treatment with sword bean pod extract increased expression of markers related to osteoblast differentiation, such as ALP, SPARC, RUNX2, COL-I, BMP2, OCN, and OPN.

Evidence strength: This is a single in vitro study with cell line data. Human clinical evidence for bone health effects is absent.

4.10 Immunomodulatory Activity

During a search for compounds with potential as therapeutic agents for allergic diseases via IL-33 signal modulation, significant IL-33 inhibitory activity was discovered in the methanol extract of Canavalia gladiata pods; 11 compounds were isolated, and three of them (compounds 7, 10, and 11) exhibited substantial IL-33 inhibitory efficacy, with values reaching 78%, 86%, and 79% at 100 µM, respectively.

Numerous studies have disclosed that effective crude extracts from C. gladiata, mainly from its fruits or seeds, possess a variety of pharmacological activities including immunomodulatory and antiallergic properties.

Evidence strength: Immunomodulatory and antiallergic effects are supported by in vitro mechanistic studies. No controlled human studies are available.

5. Body Systems and Health Areas of Association

Gastrointestinal system: Historically used for hiccups, vomiting, nausea, and chronic dysentery.
Musculoskeletal system: Traditionally used for lumbago and larynx arthralgia, and modern research points toward potential in osteoblast differentiation.
Oral/dental system: Antibacterial activity against oral pathogens and potential use as a non-alcoholic mouthwash have been reported.
Immune and inflammatory system: Laboratory studies have shown suppression of key pro-inflammatory mediators including iNOS, COX-2, TNF-α, IL-6, and IL-1β.
Metabolic system (diabetes): Antidiabetic activity has been reported in extracts and constituents.
Liver/hepatic system: Hepatoprotective activity has been demonstrated in experimental studies.
Oncology (preclinical): Antiproliferative activity against B16 melanoma cells and enhancement of natural killer (NK) cell activity have been documented in vitro.
Hematopoietic system: Improved hematopoietic dilatation has been reported in experimental models.
Reproductive system: Traditional use for amenorrhea is documented in Chinese historical medical literature.

6. Dosage Forms and Reported Dosages

The following dosages are reported in traditional pharmacopeial and ethnobotanical sources; no standardized clinical dosage has been established for any indication:

TCM decoction (seeds/beans, oral): 9–15 g as a decoction, or the seeds can be stir-baked and ground into powder.
In vitro anti-inflammatory studies (cell culture): Cells were treated with concentrations of CG or CGF at 0–400 µg/mL with or without LPS (0.1 µg/mL).
Periodontal/macrophage study (cell culture): Treatment with 6.25 µg/mL of CGENa, equivalent to 0.419 µg/mL of Con A, exhibited no cytotoxicity and significantly reduced nitric oxide production in stimulated macrophages.

More in-depth studies including pharmacological mechanism assessment, quality standardization, toxicology, and clinical research trials are needed for C. gladiata before any standardized dosage guidance can be established for therapeutic use.

7. Safety Considerations

Toxicity of Ripe Seeds

Ripe seeds contain antinutritional substances like canavanine, urease, concanavalin A and B, and canavalin; therefore, ripe seeds are not considered a primary commercial product; the ripe seeds are poisonous, and overconsumption results in nausea and tiredness; it is possible but time-consuming to detoxify by altering the cooking water, soaking, rinsing, or fermenting.

The immature seeds of C. gladiata are a popular vegetable but contain hydrogen cyanide, canavanine, and lectins, which can lead to food poisoning if consumed raw or improperly processed; in China, two poisoning incidents due to consumption of undercooked immature seeds occurred in 2019 and 2021, respectively.

Processing to Reduce Canavanine

A published study in Food and Chemical Toxicology (Ekanayake et al., 2007) specifically quantified the impact of different processing methods: overnight soaking and boiling in excess water followed by decanting gave the most pronounced reduction in canavanine content (around 50%), followed by boiling and decanting excess water (34%); roasting and autoclaving were less effective in reducing canavanine content.

Canavanine and Autoimmunity

Canavanine's toxicity has been associated with autoimmunological diseases in humans or animals feeding on plants containing this non-protein amino acid. The L-canavanine in plants has been linked to lupus-like symptoms in primates, including humans, and other autoimmune diseases; stopping consumption often reverses the problem. NZB/W F1, NZB, and DBA/2 mice fed L-canavanine developed a syndrome similar to systemic lupus erythematosus.

Antinutritional Factors

Despite its nutritional potential in terms of protein content, the species is not commonly used as a food or widely cultivated like other legumes, due to the presence of antinutritional factors such as hemagglutinins (concanavalin A), protease inhibitors, hydrocyanic acid, tannins, phytates, and canavanine.

Contraindications

In the TCM pharmacopoeial tradition, the herb is contraindicated in cases of excessive stomach heat.

Research Gaps in Toxicology and Safety

While traditional processing methods offer validated strategies for mitigating the antimetabolite canavanine, scientific caution regarding this compound is mandatory. Depth of study on main compounds should be confirmed regarding their safety and bioavailability, and pharmacokinetics and pharmacodynamic studies are still needed.

8. Overall Evidentiary Assessment

Crude extracts, fractions, and constituents from C. gladiata show various pharmacological activities in experimental settings, including antioxidant, antitumor, antimicrobial, anti-inflammatory, antiallergic, immunomodulatory, antiobesity, hepatoprotective, and antidiabetic activities. However, more in-depth studies including chemical composition, pharmacological mechanism, quality standardization, toxicology, and clinical research trials are needed for C. gladiata as a new candidate for future drug development. At present, the totality of the evidence base remains at the in vitro and animal model stages; no randomized controlled human clinical trials for any health indication attributable specifically to sword bean or its isolated constituents have been identified in the peer-reviewed literature.

References

Health Conditions

Health conditions that Sword bean may help support.

No conditions available.

Body Systems

Body systems that Sword bean may help support.

No body systems available.