garbanzo de caballo

Horse Gram (Macrotyloma uniflorum): A Comprehensive Reference

1. Identity and Botanical Description

Nomenclature and Taxonomy

Horse gram (Macrotyloma uniflorum), also known as kulthi bean, gahat, hurali, or Madras gram, is a legume native to tropical southern Asia. The currently accepted scientific name is Macrotyloma uniflorum (Lam.) Verdc., placing it in the family Fabaceae (Leguminosae). It was formerly classified as Dolichos biflorus Linn., a synonym still encountered in older Ayurvedic and pharmacological literature.

The plant is alternatively rendered as Kūlthi in Sanskrit-derived systems and Hābbūl qilt in Unani medicine. Other vernacular names include: Telugu — Ulavalu; Kannada — Huruli; Tamil — Kollu; Hindi — Kulathi.

Plant Morphology

Macrotyloma uniflorum is a perennial climbing plant with a rhizome, growing to a height of about 60 cm. The stem sprouts from the rhizome each year and is clad in varying amounts of whitish hairs, bearing alternate, trifoliate leaves with petioles up to 7 cm long. Flowers are yellow with a violet blot on the standard, and pods are 6–8 cm long and 4–8 mm wide with 6–7 seeds.

Origin, Cultivation, and Distribution

Horse gram is native to tropical southern Asia and has been found in archaeological sites in India dating from 2500 BC. The plant was probably first domesticated in India, and is now grown as a legume from India to Myanmar. Major growing areas are located in India, Africa, and Australia. Within India, the bulk of the crop (90–95% of the area) is concentrated in Tamil Nadu, Karnataka, Andhra Pradesh, and a few other major states.

Horse gram is drought tolerant and withstands harsh environmental conditions such as salinity or metal stresses. It is planted with low agronomic inputs and without weeding, and grows on a broad range of soil types with poor organic matter and nitrogen availability.

Common Forms and Preparations

The seeds are consumed whole, sprouted, or ground. Horse gram is commonly consumed as boiled seeds, sprouts, or in curries, and can also be roasted or ground into flour to enhance its nutritional quality. Traditional medicinal preparations include a cold-water infusion or decoction (kashaya) from the whole seeds, as well as a soup made by boiling the seeds. It has been used in various forms — whole seeds, flour, sprouts, and decoctions — particularly to support metabolic health and recovery from chronic illness.

2. Traditional and Historical Use

Ayurvedic Tradition

Medical uses of these legumes are described in the Ayurveda. Texts of Ayurveda refer to these beans as Kulatthika or Kulattha. The legume is recommended for weight loss in obesity, diabetes, low sperm count, erectile dysfunction, premature ejaculation, PCOS/PCOD, and Kapha-related diseases.

In Ayurvedic pharmacology, Kulattha is described as spicy to taste (katu rasa), with an astringent after-taste (kashaya rasa) following digestion, hot in potency (ushna veerya), and light to digest (laghu), increasing Pitta dosha and blood (Rakta).

Traditional Ayurvedic indications listed in classical texts include: promotion of sweating (Sweda Sangrahaka); laxative action (Sara); respiratory disorders and asthma (Shwasa); cold and cough (Kasa); hiccough (Hikka); urinary calculi (Ashmari); bloating (Anaha); rhinitis (Peenasa); obesity (Meda); fever (Jwara); hemorrhoids (Arsha); and oedema/inflammatory conditions (Shotha).

Himalayan and Folk Traditions

Since ancient times, horse gram has been used as a pulse and traditional remedy in the Himalayan Mountains for curing kidney and bladder stones, bronchitis, asthma, piles, leukoderma, and heart diseases.

By medieval times, records from Vaidya Narahari's compendium note Kulthi as a key ingredient in formulations for urinary stones, and a 12th-century commentary claims it "breaks the stone by warmth, carrying it downwards," reflecting a living practice where horse gram soup was given daily to individuals with recurrent renal colic. In folk traditions across Maharashtra and Karnataka, the seed is roasted, milled into a fine churnam, and mixed with coarse paddy water to produce a thin gruel. It was also simmered with decoctions of Punarnava (Boerhaavia diffusa) or Gokshura (Tribulus terrestris) to enhance its diuretic and lithotriptic effects.

Unani Medicine

Horse gram is also mentioned in traditional Greek medicine and is named kūlthi or Hābbūl qilt in the Unani system. Its use in Unani preparations for urinary and metabolic conditions parallels its Ayurvedic applications.

Cultural and Culinary Context

Horse gram is consumed in many parts of India and is regarded as a source of nutrients not normally found in a strictly vegetarian (sattvic) diet. It is also permitted on some Hindu fasting days. Additionally, it serves as feed for cattle, both in fresh and dried forms, benefiting dairy and poultry animals. The common name "horse gram" itself originates from its use as an important feed for horses.

3. Nutritional Composition

Macrotyloma uniflorum is known for being a rich source of protein, fat, fiber, carbohydrates, vitamins, and micronutrients. It is an excellent source of plant-based protein, essential amino acids, dietary fiber, and essential minerals such as calcium and iron.

It is reported to contain a high nutritive value with protein (approximately 23%), carbohydrates (60–70%), and fat (1%). It contains approximately 28.8% total dietary fiber, with the majority as insoluble fiber (27.82%) and a smaller portion as soluble fiber (1.13%), whereas horse gram flour contains 16.3% total dietary fiber (14.9% insoluble, 1.4% soluble, and 2.2% resistant starch).

Two varieties of horse gram from Sri Lanka showed protein content of 22.0–24.2%, crude fiber of 6.7–6.9%, and minerals (3.8%), with high dietary fiber (21.2%) and resistant starch (10.5%), yielding a reported glycemic index of 39.8.

Horse gram is a good source of both soluble and insoluble dietary fiber including β-glucan, cellulose, hemicellulose, lignin, and pectin. Resistant starch is considered a key prebiotic component and contributes significantly to horse gram's value as a functional food.

4. Key Constituents and Active Compounds

Phenolic Compounds and Flavonoids

Beyond its macronutrient and micronutrient content, horse gram is rich in bioactive phytochemicals including phenolic acids, flavonoids, phytosterols, tannins, saponins, and phytic acid, which contribute to its antioxidant, anti-inflammatory, antidiabetic, and lipid-lowering activities.

Horse gram is a rich source of flavonoids and shows antioxidant activity. Quercetin, kaempferol, and myricetin are the main flavonoids, and daidzein and genistein are the main isoflavonoids present in horse gram. Flavonoid concentration varies in different parts of the seed; the seed coat contains higher amounts of quercetin, kaempferol, and myricetin than the cotyledon and embryonic axis.

M. uniflorum contains a high amount of phenolic and flavonoid content, which performs a major function in the reduction of oxidative stress and enhances oxidative stability in food systems.

Isoflavones

The isoflavones daidzein and genistein are present in horse gram seeds. In recent years, the potential of horse gram in diabetes has been investigated, and myricetin, a major flavonol in the horse gram seed coat, is reported to play a significant role in its management.

Proteinase Inhibitors

The presence of nonnutritive bioactive compounds such as proteinase inhibitors, phenolic acid, and phytic acid has shown a significant effect on physiological and metabolic implications in human health. The proteinase inhibitors known as Bowman-Birk inhibitors (BBIs) hold promise in addressing obesity, mitigating inflammation, and managing autoimmune and degenerative conditions.

Other Bioactives

Horse gram contains phenolics, flavonoids, alkaloids, carotenoids, prebiotics, tannins, phytosterols, fatty acids, saponins, terpenoids, and dietary fibers as possible health-promoting bioactive components (both soluble and insoluble).

Anti-Nutritional Factors

Horse gram contains anti-nutritional factors such as phytic acid and saponins, which can interfere with nutrient absorption. Anti-nutritional factors in horse gram varieties include phytic acid, saponins, and trypsin inhibitors. However, tannins, saponins, and phytic acid, though commonly regarded as anti-nutritional factors, also possess strong antioxidant and therapeutic properties that contribute significantly to the health-promoting potential of horse gram.

Effect of Processing on Constituents

Phytic acid content in horse gram seeds is significantly reduced by 69.5% after fermentation and by 61.6% during germination. Fermentation of germinated and cooked horse gram flours has been reported to reduce phytate content by 54.1% and 46.8%, respectively. Dehulling and germination also significantly decrease tannin and oxalic acid content. Fermentation and microwave methods enhance antioxidant activity, whereas the extrusion method reduces it.

5. Mechanisms of Action

Antioxidant Mechanisms

The antioxidant activities of M. uniflorum extracts have been shown to combat oxidative stress, with mechanisms that involve scavenging various radical species and enhancing the activity of antioxidant enzymes.

Antidiabetic Mechanisms

Studies have demonstrated that extracts of Macrotyloma uniflorum exhibit the ability to inhibit alpha-amylase, an enzyme crucial for regulating blood glucose levels, thus presenting a promising option for diabetes management. Studies in diabetic rats have shown that horse gram seed extracts can reduce blood glucose levels and improve lipid profiles, possibly by enhancing insulin sensitivity and inhibiting the absorption of carbohydrates in the gut.

Anti-Lithiatic Mechanisms

At least two inhibitors of crystallization of calcium phosphate — one of the significant constituents of kidney stones — are available in horse gram seed concentrates, and these are identified as non-protein, water-soluble, and heat-stable compounds. The ability of horse gram seed beverages to prevent the accumulation of calcium oxalate crystals is attributed to the abundance of phenols, flavonoids, and antioxidants.

The main underlying mechanisms of dietary plants including horse gram in the management of urolithiasis include diuretic, antispasmodic, and antioxidant activity, as well as an inhibitory effect on crystallization, nucleation, and aggregation of crystals.

Anti-Inflammatory Mechanisms

Research has identified horse gram as possessing considerable antimicrobial and anti-inflammatory characteristics, with plant extracts demonstrating effectiveness against various bacterial and fungal strains, illustrating its role in enhancing immune responses.

6. Scientific Evidence by Area of Use

6.1 Urolithiasis (Kidney and Bladder Stones)

This is the most extensively studied application of horse gram, reflecting its deep traditional use for urinary calculi.

Dolichos biflorus (horse gram) has received considerable scientific interest as a dietary plant for the prevention and management of kidney stones, based on a 2018 systematic review published in PMC that examined preclinical and clinical evidence and molecular mechanisms.

In vitro and animal work: Gautam et al. (2020) investigated the efficiency of aqueous, ethanol, and 50% ethanol extracts of horse gram seed for calcium oxalate crystal (CaOx) inhibition potential by various methods such as agar gel overlay, artificial urine method, and nucleation assays; the highest crystal inhibition activity was observed in the aqueous extract.

The nephroprotective activity of an aqueous functional beverage prepared from M. uniflorum seeds was tested against ethylene glycol-induced urolithiasis in rats. The functional beverage at a dose of 2 ml reduced oxalate by 74–89% and increased citrate by 66–92% in both serum and urine. These are animal-model data only.

In another study, a 2% dose of horse gram extract and 250 µg/mL of horse gram silver nanoparticles (AgNPs) were found to be very effective in dissolving and preventing crystals from the sixth day of administration by forming complexes with magnesium ions.

Evidence strength: The anti-urolithiatic evidence for horse gram consists predominantly of in vitro and animal studies. Horse gram and its crude extracts or fractions have been shown to exhibit a wide range of in vivo and in vitro pharmacological properties; however, there is currently a scarcity of structure-activity investigations of isolated compounds and mechanistic research. No large-scale, controlled human clinical trials specific to horse gram and kidney stone prevention have been identified in the peer-reviewed literature to date.

6.2 Glycemic Control and Diabetes

Macrotyloma uniflorum (formerly Dolichos biflorus) is an underutilized legume with potential as a low glycemic index (GI) food due to its slow rate of starch digestion.

A study by Baruah and Arya (2021) was conducted to determine the effect of soaking, roasting, and germination of horse gram in different product forms and its impact on blood glucose and glycemic index of normal and diabetic subjects, using standard methods. Results indicated that horse gram sprouts (germinated) had a significantly low glycemic index. The mean glycemic index of horsegram cheela, horsegram curry, and horsegram sprouts in normal subjects were 84.12 ± 1.95, 68.21 ± 3.58, and 60.59 ± 3.66, respectively.

Germinated horse gram as well as horse gram curry (soaking) exhibited a glycemic index value of less than 30 in diabetic subjects, compared to higher values in normal subjects, suggesting horse gram may be incorporated in dietary management of diabetes.

Animal evidence: Studies in diabetic rats have shown that horse gram seed extracts can reduce blood glucose levels and improve lipid profiles, possibly by enhancing insulin sensitivity and inhibiting gut carbohydrate absorption.

Evidence strength: Small human dietary studies support a low-to-moderate glycemic index for certain preparations of horse gram, particularly sprouted forms, and animal studies support antidiabetic mechanisms. Clinical data are still needed to fully understand pharmacological effects using well-designed laboratory and clinical models.

6.3 Antioxidant Activity

Horse gram has high levels of antioxidant and radical scavenging activities in addition to its traditional role of providing proteins and carbohydrates. It possesses potent properties to scavenge free radicals. These findings are based primarily on in vitro assays measuring DPPH, ABTS, and similar radical-scavenging parameters in seed extracts and fractions. No controlled human trials specifically examining antioxidant biomarkers after horse gram consumption have been identified in the reviewed literature.

6.4 Anti-Inflammatory Activity

The bioactive compounds in horse gram have demonstrated antioxidant, antidiabetic, anti-inflammatory, anticarcinogenic, antimicrobial, antidiarrheal, and neuroprotective effects. Anti-inflammatory studies have been conducted in animal models and in vitro systems. A PubMed-indexed study (PMID 28987361) examined the comparative effect of horse gram and black gram on inflammatory mediators and antioxidant status, reflecting this area of preclinical inquiry. Human clinical evidence for anti-inflammatory effects is currently lacking.

6.5 Antimicrobial Activity

Very limited studies have been conducted to date for estimating the antimicrobial activity of horse gram, and more focused research should be conducted to diversify the scope to include different parts of the plant, including the leaves, which studies have confirmed contain numerous bioactive compounds. Existing evidence is confined to in vitro disk diffusion and broth dilution assays against selected bacterial and fungal strains.

6.6 Anticancer / Anticarcinogenic Activity

Cancer continues to be one of the biggest global health issues. Although cancer cannot be completely prevented by diet alone, 30–50% of all cancer cases can be prevented by dietary means. Several plants, including horse gram, have been studied for their anticancer properties; the presence of phytochemicals and antioxidants are the potential components responsible for this property.

Chakraborty & Abraham (2016) assessed methanolic and ethanolic extracts of horse gram for anticancer potential against the MG-63 (human osteosarcoma) cell line. Methanolic extracts decreased cell viability and exhibited moderate anticancer activity; methanolic and ethanolic extracts at 200 µg/mL concentration resulted in 82% and 74% cell viability, respectively. These are in vitro findings only, with no human clinical trials identified.

6.7 Lipid Profile and Cardiovascular Health

The fiber profile of horse gram supports bowel regularity, helps lower serum cholesterol, and contributes to better glycemic control. Consuming pulses can have a favorable effect on cardiovascular health as they improve serum lipid profiles, reduce blood pressure, decrease platelet activity, regulate blood glucose and insulin levels, and reduce inflammation. These benefits are attributed to the legume class generally and to horse gram's specific fiber and phytochemical content. Specific cardiovascular clinical trials in human populations with horse gram have not been identified in the literature to date.

6.8 Gastroprotective Activity

Laboratory studies referenced in the literature (Panda & Suresh, 2015, cited in Food Res Int) have explored gastroprotective effects of the phenolic acids of horse gram on experimental gastric ulcer models in animals. Horse gram and its crude extracts or fractions have been shown to exhibit a wide range of in vivo and in vitro pharmacological and nutraceutical properties. Human gastric data are currently absent from the peer-reviewed record.

7. Body Systems and Health Areas Associated with Horse Gram

• Urinary/Renal System: Horse gram's importance in folk and traditional medicine as a potential therapeutic agent to treat kidney stones and urinary diseases is well recognized.
• Metabolic/Endocrine System: Recent studies have demonstrated horse gram's potential role in preventing and managing chronic disorders such as cardiovascular diseases, diabetes, and obesity.
• Respiratory System: Since ancient times, it has been used as a traditional remedy for bronchitis and asthma.
• Digestive System: The fiber profile supports bowel regularity and contributes to better glycemic control.
• Integumentary System: Horse gram has been traditionally used for leukoderma.
• Immune / Inflammatory System: Bowman-Birk inhibitor (BBI) proteinase inhibitors in horse gram have been identified as having potential for treating anti-inflammatory, obesity, and several degenerative and autoimmune diseases.
• Cardiovascular System: Heart diseases have been traditionally addressed with horse gram-based preparations in the Himalayan region.

8. Dosage Forms and Doses Reported in Studies

No universally standardized pharmaceutical dosage for horse gram has been established. The following forms and quantities appear in published research and traditional sources:

• Whole boiled seeds / soup: Used traditionally as a daily dietary preparation; no standardized clinical dose established.
• Aqueous seed extract (beverage): In a rat urolithiasis study, an aqueous functional beverage of M. uniflorum seeds was administered at a dose of 2 ml, reducing oxalate by 74–89% and increasing citrate by 66–92%. (Animal data only.)
• Horse gram extract / AgNPs (in vitro): A 2% dose of horse gram extract and 250 µg/mL of horse gram silver nanoparticles were found effective in dissolving and preventing crystals from the sixth day of administration. (In vitro / experimental data.)
• Methanolic/ethanolic extract (in vitro): Methanolic and ethanolic extracts at a 200 µg/mL concentration were assessed for anticancer activity against osteosarcoma cell lines. (In vitro data only.)
• Dietary supplementation (glycemic index studies): In the Baruah and Arya (2021) human study, blood glucose response and glycemic index were recorded for different processed forms (cheela, curry, sprouts) using standard methods in normal and diabetic subjects. Specific gram-weights consumed in the study were not extracted from the search results.

No official monograph (WHO, ESCOP, German Commission E, USP) establishing a standardized dose for horse gram as a medicinal supplement was identified in the reviewed sources.

9. Safety Considerations

Anti-Nutritional Factors and Mineral Absorption

Horse gram contains anti-nutritional factors such as phytic acid and saponins, which can interfere with nutrient absorption. Horse gram has several anti-nutritional factors that are reduced by soaking, de-husking, sprouting, heating, and roasting — including hemagglutinin activity, trypsin inhibitor, phytic acid, and tannin.

Phytic acid content is significantly reduced by 69.5% after fermentation and by 61.6% during germination in horse gram seeds. Multiple studies have found that soaking for 12 to 18 hours is the optimum approach to reduce the levels of anti-nutritional chemicals such as phytic acid and proteolytic enzyme inhibitors that are entirely or partially dissolved in steeped water.

Gastrointestinal Effects

Horse gram may cause allergic reactions in some people and contains a type of carbohydrate that may cause gas and bloating. Flatulence-causing oligosaccharides are present in horse gram; however, these and other antinutrients are now being considered as potential antioxidants that cause a number of positive health effects, including decreased risk of intestinal diseases such as gallstones, diverticulosis, constipation, and colon cancer.

Gout and Hyperuricemia

In traditional Ayurvedic guidance, horse gram (kulthi dal) is listed among legumes to be stopped or minimized in patients with gouty arthritis and hyperuricemia. This caution is consistent with the general principle that legumes are among purine-rich foods; since purine-rich food may contribute to uric acid elevation, they are not suitable for everyone.

Phytic Acid: Dual Roles

While phytates may hinder mineral absorption, they also play a protective role by inhibiting lipid peroxidation. This dual character is important context for safety assessment; the net effect on mineral status depends significantly on the preparation method used and total dietary context.

Overall Safety Profile

There is currently a scarcity of structure-activity investigations of isolated compounds and mechanistic research on this species. Despite its traditional usage by diverse cultures and a profusion of bioactive chemicals with a wide range of biological effects, rigorous safety and toxicology data from human clinical trials are limited. Although horse gram has traditionally been used for the treatment of several diseases, very limited clinical research has been conducted, and clinical data are needed to understand pharmacological effects.

10. Evidence Gaps and Research Status

A 2024 systematic review published in the Journal of Food Science (DOI: 10.1111/1750-3841.17594) — the most current comprehensive review identified — covers traditional uses, phytochemistry, pharmacology, and nutraceutical potential of horse gram. The review concludes that:

• Horse gram and its crude extracts or fractions have been shown to exhibit a wide range of in vivo and in vitro pharmacological and nutraceutical properties; however, there is a scarcity of structure-activity investigations of isolated compounds and mechanistic research.
• Very limited studies have been conducted to date for estimating the antimicrobial activity of horse gram, and more focused research should be conducted to include different plant parts.
• Clinical data are needed to understand pharmacological effects using laboratory and animal models.

In summary, the preponderance of evidence for horse gram's health effects is derived from in vitro assays, animal models, and small human dietary studies. Large-scale, randomized controlled trials in human populations remain absent from the published record for all therapeutic claims.

References

• Oli P, Joshi K, Punetha S. Traditional uses, phytochemistry, pharmacology, and nutraceutical potential of horse gram (Macrotyloma uniflorum): A systematic review. Journal of Food Science. 2024;89:8102–8127. PubMed PMID: 39656760.
• Horse gram – an underutilized nutraceutical pulse crop: a review. PMC (PubMed Central), PMCID: PMC4397296.
• Bioactive Compounds of Horse Gram (Macrotyloma uniflorum Lam. [Verdc.]). In: Bioactive Compounds in Underutilized Vegetables and Legumes. Springer Reference Series in Phytochemistry. 2020.
• Dietary Plants for the Prevention and Management of Kidney Stones: Preclinical and Clinical Evidence and Molecular Mechanisms. PMC (PubMed Central), PMCID: PMC5877626. PubMed PMID: 29518971.
• Assessment of calcium oxalate crystal inhibition potential, antioxidant activity and amino acid profiling in horse gram (Macrotyloma uniflorum): high altitude farmer's varieties. PubMed PMID: 32879839.
• Nutritional Profile and Therapeutic Properties of Horse Gram (Macrotyloma uniflorum). International Journal of Nutrition, Open Science Publications. 2025.
• Baruah LD, Arya A. Effect of Processing of Horsegram (Macrotyloma uniflorum) on the Glycemic Index Value of Normal and Diabetic Subjects. Acta Scientific Pharmaceutical Sciences. 2021;5(7):02–07.
• Effect of Processing of Horsegram on the Glycemic Index Value of Normal and Diabetic Subjects. ResearchGate (request PDF).
• Gupta et al. Nutritional and Medicinal Potential of Macrotyloma uniflorum (Horse Gram): A Review. Journal of Food Processing and Preservation. 2026. Wiley Online Library.
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• Macrotyloma uniflorum. Wikipedia.
• Therapeutic Potential and Nutritional Benefits of Horse Gram. Asian Journal of Dairy and Food Research. ARCC Journals.
• Anti-hyperglycemic activity of myricetin, through inhibition of DPP-4 and enhanced GLP-1 levels, is attenuated by co-ingestion with lectin-rich protein. PMC PMCID: PMC7153899.
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