IngredientsGum karaya, also known as gum sterculia and Indian gum tragacanth, is a vegetable gum produced as an exudate by trees of the genus Sterculia. As specified in Commission Regulation (EU) No 231/2012, it is derived from the exudates from the stems and branches of strains of Sterculia urens Roxburgh and other species of Sterculia (family Sterculiaceae), or from Cochlospermum gossypium A.P. De Candolle or other species of Cochlospermum (family Bixaceae).
Known in India as Indian tragacanth or karaya gum, the tree is native to India and is widely distributed across agroecological regions. The names kullo, katera, and tapsi are also used regionally. As a food additive, it carries E number E416.
Karaya gum is a complex, partially acetylated polysaccharide obtained as a calcium and magnesium salt. The polysaccharide component of karaya has a high molecular weight and is composed of galacturonic acid, beta-D-galactose, glucuronic acid, L-rhamnose, and other residues. Gum karaya has a ramnogalacturonane-type, partially-acetylated ramified structure and is commercially obtained in the form of calcium and/or magnesium salt. It has a molecular weight of 16Γ10Β³ kDa and is composed of 55β60% neutral monosaccharide units (galactose and rhamnose), 8% acetyl groups, and 37β40% acid residues (galacturonic and glucuronic acids).
It is a partially acetylated biopolysaccharide containing three dissimilar chains. The first chain comprises approximately 50% of the total polysaccharide, made of four galacturonic acid residues as repeating units, L-rhamnose residues at the reducing end, and a beta-D-galactose branch. The second chain comprises approximately 17% of the total polysaccharide, made of an oligorhamnan containing D-galactose residues and D-galacturonic acid branch. The third chain comprises approximately 30% of the total polysaccharide, made of D-glucuronic acid residues comprising galactose, rhamnose, and uronic acid residues.
The quality of karaya gum depends on the thoroughness of impurity removal. Food-grade gum is usually a white to pinkish-gray powder with a slight vinegar odor from acetic acid released during storage. Pharmaceutical grades of karaya may be almost clear or translucent. Karaya gum is the least soluble of commercial plant exudates, but absorbs water rapidly and swells to form viscous colloidal solutions even at low concentrations (1%). Unlike other gums, karaya swells in 60% alcohol but remains insoluble in other organic solvents. It acts as a bulk-forming laxative by stimulating the digestive tract through its swelling in the intestine due to its high water-binding properties. Gum particles absorb water and swell to 60β100 times their original volume.
The native acetylated karaya gum assumes a rather compact and branched conformation in aqueous solution, as evidenced by low values of power-law exponents. In contrast, the fully deacetylated karaya gum assumes a more expanded conformation and behaves as a random coil. Karaya gum exhibits non-Newtonian pseudoplastic behavior with viscosity ranging from 120β10,000 cPs at varying concentrations.
Karaya gum is traditionally tapped by cutting or peeling back the bark, or by making deep gashes at the base of the trunk with an axe. These crude methods of extraction often resulted in the death of the tree, but it has been found that application of the plant growth regulator ethephon stimulates the production of gum. Commercially available forms include crude dried lumps, a milled white-to-cream powder suitable for food and pharmaceutical use, granules formulated as laxatives, pastes and wafers for ostomy applications, and as a component of denture adhesive strips and creams.
Tribal species use Sterculia urens gum as traditional medicine to cure various ailments. Its medicinal value has been recognized in traditional Indian medicine systems such as Ayurveda and Unani. The use of Sterculia urens in Ayurvedic tradition dates back over a thousand years, with early mentions found in classical texts like the Bhavaprakasha Nighantu (~16th century CE) and in regional folk practices recorded by colonial botanists in the 19th century. In the Bhavaprakasha, karaya gum is classified under "Sthaviryavardhaka" agents, believed to enhance strength and support tissue healing.
Medicinally, it was employed to treat blisters, blood dysentery, joint pain, stomach disorders, and throat infections. The gum extract was applied locally to remove spines from the skin, and it was known to treat leucoderma, peptic ulcers, and to regulate menstrual disorders. Various parts of the plant, especially the gum, bark, and leaves, were traditionally used for treating ailments such as constipation, wounds, cough, inflammation, dysentery, joint pain, and digestive issues.
Traditional healers in Rajasthan and Gujarat valued its demulcent action, using decoctions of the gum to soothe inflamed throats and treat dysentery. Historical manuscripts describe its use in postpartum care, where a milky karaya gum paste was given to new mothers to ease constipation and replenish vital fluids.
Traditionally, it was also used in pharmaceuticals, tanneries, and for making agarbati (incense sticks).
Karaya gum has been used commercially for approximately 100 years. Its use as an adulterant or as an alternative to tragacanth gum became widespread during the early 20th century. Experience indicated that karaya gum was less expensive and possessed certain physiochemical properties that made it more useful than tragacanth gum. Traditionally, India has been the largest producer and exporter of karaya gum. The gum has been used in a variety of products, including cosmetics and lotions, and as a bulking agent.
Gum karaya has been used for many centuries in traditional African and Indian cooking. The physico-chemical and microbiological characteristics of karaya gum vary depending on their origin: African gum is known to provide higher viscosity and swelling potency, and Indian gum offers good microbiological quality.
The gum's main chain is formed by alpha-D-galacturonic acid and L-rhamnose units. Side chains are linked to the main chain by 1,2-beta-D-galactose bounds or 1,3-beta-D-glucuronic bound for galacturonic acid. The partial acetylation of the molecule is a defining feature that governs its solubility and rheological behavior: the native acetylated form is more compact, whereas removal of acetyl groups yields a more expanded, random-coil structure in solution.
The astringent bark contains alpha cellulose, botulin, and tannin. In addition, seeds of the karaya plant contain carbohydrates and lignoceric, linoleic, myristic, oleic, palmitic, and stearic acids.
The protein content of karaya gum (E 416) from Sterculia spp. is less than 0.63%; the protein content for karaya gum derived from Cochlospermum spp. was found to be in the range of 5β6.3%. The EFSA panel has noted that hypersensitivity reactions may be attributable to these protein fractions.
The trend for the decreasing concentration of elements determined in the gum sample is Mg > Ca > Mn > Zn > Fe > Ni > Cu > Cd > Pb. The gum occurs in commerce predominantly as its calcium and magnesium polysaccharide salts.
The action of karaya gum is described as a bulk-forming laxative by the stimulation of the digestive tract through its swelling in the intestine due to its high water-binding properties. Gum particles absorb water and swell to 60β100 times their original volume. Karaya gum does not disintegrate or decompose appreciably in the alimentary tract. In a study of 10 dogs, 95% of the orally administered gum was recovered in the faeces. It absorbs a large quantity of water and therefore acts as a mechanical laxative.
Rhamnose was not detected in the urine of animals administered the gum. The absence of this component demonstrates that it is not liberated from karaya gum during its transit through the intestine. These findings indicate that extensive degradation involving chains and chain terminations did not occur.
Karaya gum increased faecal but not caecal short-chain fatty acids (SCFAs) in the rat in vivo. According to the authors, the fermentation of karaya gum in the rat may be higher than that measured in human faeces, in which very little evidence of fermentation was observed using different human faecal donors. Whatever the duration of in vitro incubation, organic matter disappearance and acetate, propionate, and butyrate production were low in the case of karaya gum compared to other gums like acacia gum and particularly locust bean gum or guar gum.
Due to its water-binding properties, karaya gum is also used as an antidiarrhoeal drug. The same capacity to retain water that produces stool bulk in constipation may bind and retain free fluid in diarrhoeal states.
Sterculia gum has many distinguishable properties, including high viscous rheology, excellent acidic stability, good swelling ability, biodegradability, and biocompatibility. In topical and ostomy applications, the polysaccharide forms a hydrophilic gel that adheres to moist surfaces, creating a physical barrier and promoting a moist wound environment.
The earliest dedicated clinical investigation into karaya gum as a laxative dates to the mid-20th century. An early study (published in the American Journal of Digestive Diseases) found that a karaya-based preparation increased the bulk of the stool in 80.8% of human subjects studied, increased moisture content in 75.2%, increased the number of defecations in 53.9%, and increased the urge to defecate in 42.7%. It relieved constipation in 19 of 23 persons studied. The preparation produced no harmful effects and was not habit-forming if taken over long periods of time. The evidence suggested its value as a regulator of bowel habit. These findings must be interpreted in light of the study's age and the limited methodological rigor of clinical research conducted in that era.
A more recent controlled human study yielded notably different results. Following a 7-day control period, 5 male volunteers consumed 10.5 g of gum karaya daily for 21 days. Measurements before and at the end of the test period showed that ingestion of gum karaya had no significant effect on intestinal transit time, faecal wet or dry weight, concentrations of faecal fat, total and individual volatile fatty acids, bile acids, and neutral sterols; breath hydrogen and methane concentrations; glucose tolerance; serum cholesterol, HDL cholesterol, triglycerides and phospholipids; plasma biochemistry; haematological indices; or urinalysis parameters. The daily test intake did not cause any toxic effects, and the gum had no metabolic action of any consequence.
There are no recent animal data regarding the use of karaya gum as a laxative. A 2009 systematic review assessing fiber supplements for use in adults with idiopathic chronic constipation identified no randomized controlled trials or systematic reviews evaluating Sterculia; the effectiveness of Sterculia in this patient population is therefore unknown.
Evidence strength: Weak to insufficient. The existing human data are based on a small, early uncontrolled series and one small controlled trial with null metabolic results. No robust modern RCTs have been conducted specifically on karaya gum for constipation.
The indications listed for karaya gum in medicinal products include the symptomatic treatment of irritable bowel syndrome, diarrhoea, constipation, and flatulence. However, these indications are based largely on traditional use and physiochemical reasoning rather than clinical trial evidence. No dedicated RCTs in IBS populations for karaya gum specifically were identified in available literature.
Evidence strength: No clinical trial evidence; indications rest on traditional use and mechanistic rationale.
Animal and in vitro studies of karaya gum have suggested anti-inflammatory, hypocholesterolemic, laxative, antiproliferative, antioxidant, and antimicrobial effects. Regarding cholesterol specifically, hypocholesterolemic properties were demonstrated by Behall, Lee, and Moser (1984). Separately, Afrose, Hossain, Maki, and Tsujii (2009) elaborated a comparative assay with several saponins and showed that karaya root saponins had better effects in reducing blood and hepatic cholesterol, blood low-density lipoprotein, and atherogenic index, and in increasing serum high-density lipoprotein and the HDL/cholesterol ratio in comparison with other saponins from tea, soybean, and quillaja in rats fed a high-cholesterol diet.
The single small controlled human study that measured serum lipids found no significant effect: ingestion of 10.5 g of gum karaya daily for 21 days had no significant effect on serum cholesterol, HDL cholesterol, triglycerides, or phospholipids.
Evidence strength: Animal and in vitro data only for hypocholesterolemic effects. The available human data (one small, short-duration study) showed no lipid-lowering effect. No clinical trials are available to confirm animal findings.
Some in vitro and animal studies have investigated gum karaya's role in modulating cholesterol absorption and glycaemic response, with preliminary results indicating a possible beneficial effect. However, the controlled human study in 5 male volunteers consuming 10.5 g daily for 21 days found that ingestion of gum karaya had no significant effect on glucose tolerance.
Evidence strength: Preliminary in vitro and animal data only. The one available human study showed no significant effect on glucose tolerance.
Martindale (2014) states the usage of karaya gum as an aid to appetite control in the management of obesity but also states that there is little evidence of efficacy.
Evidence strength: Claimed on the basis of the gum's water-absorbing and bulking properties, but without clinical trial support; explicitly noted to have little evidence of efficacy.
Sterculia gums, including karaya, are complex branched and polydisperse heteropolysaccharides which can have their applications extended by improving their characteristics through chemical modifications. Research has aimed to increase the antimicrobial activity of karaya gum through chemical modification with maleic anhydride. The chemically modified derivatives showed excellent antibacterial action, inhibiting almost 100% of bacterial growth against Staphylococcus aureus, and did not present significant cytotoxicity in mammalian cells.
Evidence strength: In vitro evidence only, and primarily for chemically modified (esterified) derivatives rather than the native gum. No human clinical data exist.
One published clinical application for karaya gum in dermatology involves its use as a vehicle for salicylic acid in wart treatment. Salicylic acid in karaya gum patch has been studied as a treatment for verruca vulgaris, published in the Journal of the American Academy of Dermatology (1989). In this application, karaya gum functions primarily as a delivery matrix rather than as the active pharmaceutical ingredient.
Karaya gum has been used in ostomy care, as a base for transdermal delivery of medicines. Its use in peristomal skin care is well established in clinical practice. Karaya gum is an acid polysaccharide used as a thickener and emulsifier in foods, as a laxative, as a denture adhesive, and in seals for stomas. The gum is applied as a powder to moist, excoriated peristomal skin where its extreme water-absorbing capacity dries the wound surface, allowing adhesion of ostomy appliances. Its mildly acidic pH (approximately 4.5β4.7) is considered compatible with the normal skin surface pH range.
Karaya gum has been investigated as a carrier or release-controlling agent for poorly soluble medicines and has been tested as a biosorbent for remediation of toxic heavy metal ions. Research into karaya gum hydrogels, grafted polymers, and microsphere formulations for controlled oral and transdermal drug delivery represents an active area of pharmaceutical science, though these applications are at the preclinical or materials-science stage.
In medicinal products, the dosage of karaya gum for adolescents and adults is up to 12 g/person per day, administered up to three times daily (4 g per dose, equivalent to 170 mg/kg body weight per day for a 70-kg person).
In a controlled human volunteer study, 5 male subjects consumed 10.5 g of gum karaya daily for 21 days.
Karaya gum from Sterculia spp. was well tolerated in humans at a dose of about 100 mg/kg body weight per day for 4 weeks.
The EFSA Panel concluded that exposure to karaya gum by use as a food additive should not exceed 7,000 mg/person per day in adults, the level at which some individuals experienced abdominal discomfort.
There are no clinical data to support the use of karaya gum for any specific therapeutic use, and clinical studies are lacking to provide dosing recommendations. The dosages cited above are those reported in specific human tolerance studies and pharmacopoeial pharmaceutical monographs, not evidence-based therapeutic doses established by controlled trials.
Karaya gum is generally recognized as safe (GRAS) by the US Food and Drug Administration (FDA). The EFSA Panel concluded that there is no safety concern at the refined exposure assessment for the use of karaya gum as a food additive, and that there is no need for a numerical acceptable daily intake (ADI) for karaya gum. An ADI "not specified" was allocated by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), whereas the Scientific Committee for Food (SCF) allocated an ADI of 12.5 mg/kg body weight per day.
Karaya gum is practically undigested and not degraded by intestinal microflora, and it is most probably not, or only negligibly, absorbed unchanged in humans. Karaya gum (E 416) from Sterculia spp. did not induce toxic effects in animals at dose levels up to 1,250 mg/kg body weight per day, the highest dose tested. There is no concern with respect to the genotoxicity of karaya gum from Sterculia spp.
The repeated short-term oral administration of karaya gum to mice, rats, dogs, and monkeys did not induce toxic effects. Although slight growth depression was observed in female rats fed a diet with 5% karaya gum in one subchronic study, corresponding to approximately 4,800 mg/kg body weight per day, this effect was not observed in other studies with similar or higher doses.
Ingestion or inhalation has been reported to have caused allergy. Sixteen cases of allergic sensitivity to inhalation of the gum used as a hair wave set and to oral ingestion as a laxative were reported. Symptoms included hay fever, asthma, dermatitis, and gastrointestinal distress (Figley, 1940).
Gum karaya is capable of eliciting an immune response which is comparable to the specific immune responses elicited by a protein antigen, hen's egg ovalbumin. The EFSA Panel noted case reports of hypersensitivity reactions associated with karaya gum and considered that this hypersensitivity might be due to the proteins present in karaya gum (E 416).
Aside from allergy, case reports of adverse reactions are limited; however, excessive doses as a laxative may cause diarrhea, and with inadequate water consumption, may result in bowel obstruction. A case of esophageal blockage occurred in a man who consumed dry karaya gum stool bulking granules without drinking water or liquid. Esophageal obstruction after ingestion of sterculia has been reported. A 91-year-old man presented with complete esophageal obstruction after taking a tablespoonful of sterculia granules (Normacol) without water. There was no predisposing esophageal disease.
Karaya gum may affect the absorption of oral medications due to its gelling properties. It is advisable to take medications and gum karaya at different times. No specific pharmacokinetic interaction studies between karaya gum and named pharmaceutical drugs were identified in the peer-reviewed literature reviewed; the interaction concern is a class effect shared with all bulk-forming hydrocolloids.
Information regarding safety and efficacy in pregnancy and lactation is lacking.
Bulk-laxatives, including karaya gum, should not be used in individuals with bowel obstruction. No other specific contraindications have been identified in the published regulatory and peer-reviewed sources reviewed.
Because of the botanical origin, the polysaccharidic nature, and the possible contamination by soil and air during collecting and sorting, gums can be a substrate of microbiological contamination and of field and storage fungal development. Quality control of commercial grades is thus important for both safety and efficacy.
Health conditions that Karaya gum may help support.
Body systems that Karaya gum may help support.
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