Karaya Gum

Scientific Name(s): Sterculia urens Roxb.
Common Name(s): Bassora tragacanth, Indian chestnut, Indian tragacanth, Kadaya, Kadira, Karaya, Katila, Kullo, Mucara, Sterculia

Botany

The majority of commercial karaya gum is obtained from S. urens, a soft-wood tree that grows to approximately 10 m. The small, yellow flowers bloom from February to March, and the tree bears a star-shaped fruit.1, 2

The plant is native to India and Pakistan, where it is found on the dry, rocky hills and plateaus and is cultivated for karaya production.3 All parts of the tree exude a soft gum when injured. Karaya gum is produced by charring or scarring the tree trunk and removing a piece of bark or by drilling holes into the trunk. The gum seeps from the scars and is collected, washed, dried, and then graded. A mature tree may yield 1 to 5 kg of gum per season.1, 3, 4

History

Karaya gum has been used commercially for approximately 100 years. Its use became widespread during the early 20th century, when it was used as an adulterant or as an alternative to tragacanth gum.3 However, experience indicated that karaya possessed certain physiochemical properties that made it more useful than tragacanth and less expensive. Traditionally, India has been the largest producer and exporter of karaya gum.3 The gum has been used in a variety of products, including cosmetics and lotions, and as a bulking agent.5 The fruit of the related Sterculia villosa has been used traditionally as an antidiabetic agent in India.6

Chemistry

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.1, 2

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.1 Pharmaceutical grades of karaya may be almost clear or translucent.2

Karaya gum is the least soluble of commercial plant exudates, but it absorbs water rapidly and swells to form viscous colloidal solutions even at low concentrations (1%).1 The swelling reaction of karaya gum is dependent upon the presence of acetyl groups in its structure. Deacetylation through alkali treatment results in a water soluble gum. When used in higher concentrations in water (up to 4%), karaya forms gels or pastes. Unlike other gums, karaya swells in 60% alcohol but remains insoluble in other organic solvents. Karaya may absorb up to 100 times its weight in water.1

The astringent bark, containing alpha cellulose, botulin, and tannin, has also been investigated.2, 7 Sesquiterpenoids possessing antiproliferative properties have been identified in the bark of the related Madagascan species Sterculia tavia.8

In addition, seeds of the karaya plant contain carbohydrates and lignoceric, linoleic, myrstic, oleic, palmitic, and stearic acids.7 Cerebroside chemicals, with antioxidant properties, and polysaccharides have been identified in the related species Sterculia lychnophora, that is used in traditional Chinese medicine,9, 10 whereas lectins have been identified in Serissa foetida seeds.11

Uses and Pharmacology

Anti-inflammatory effects

Animal data

Extracts of S. lychnophora10 seeds and Sigara striata12 bark were effective in reducing ear and paw edema and writhing in mice.

Clinical data

There are no clinical data regarding the use of extracts of Sterculia species for anti-inflammatory effects.

Dyslipidemia

Animal data

Limited studies in hens and quails suggest karaya saponin may exert a hypocholerstolemic effect.13, 14

Clinical data

No clinical data exist regarding the use of karaya extracts for the management of dyslipidemia. Earlier preliminary studies suggested that gums may normalize blood sugar and plasma lipid levels.15

Laxative

Animal data

There are no recent animal data regarding the use of karaya gum as a laxative. Studies were conducted in dogs in the 1930s.16

Clinical data

Karaya gum particles absorb water and swell to 60 to 100 times their original volume, making it useful as a bulk laxative.1, 3, 17 Excessive doses as a laxative may cause diarrhea and, with inadequate water consumption, may result in bowel obstruction.18 Recent clinical data is lacking.

Other uses

Karaya gum has also been used as an adhesive for dental fixtures. A protective coating of karaya gum applied to dentures has been shown to reduce bacterial adhesion by 98%.19

The gum has been used in ostomy care, as a base for transdermal delivery of medicines,20, 21 and as a carrier for poorly soluble medicines.22, 23 Similarly, the gum has been tested as a biosorbent of toxic heavy metal ions.24

Antiproliferative properties of the bark of the related Madagascan S. tavia plant have been described,8 whereas antioxidant properties have been identified in the related plant S. lychnophora, used in traditional Chinese medicine.9 Antimicrobial activity against human pathogens was demonstrated by lectins extracted from the seeds of S. foetida.11

Dosing

No specific dosage of karaya gum preparations has been determined by clinical studies. Studies conducted in the 1980s used doses of 10 g/day.16

Pregnancy / Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented. Use with antiperistalsis agents (eg, loperamide) is unadvisable.1

Adverse Reactions

A report published in 1989 found that widespread use of karaya gum throughout the United States and Europe was not associated with any clinically important adverse experiences.25 Aside from allergy,16 case reports of adverse reactions with the use of karaya gum are limited; however, excessive doses as a laxative may cause diarrhea and, with inadequate water consumption, may result in bowel obstruction.18

Toxicology

Karaya gum is GRAS for internal consumption.25 Studies conducted in the 1970s and 1980s found no evidence of mutagenicity or teratogenicity.16

References

Disclaimer

This information relates to an herbal, vitamin, mineral or other dietary supplement. This product has not been reviewed by the FDA to determine whether it is safe or effective and is not subject to the quality standards and safety information collection standards that are applicable to most prescription drugs. This information should not be used to decide whether or not to take this product. This information does not endorse this product as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this product. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this product. This information is not specific medical advice and does not replace information you receive from your health care provider. You should talk with your health care provider for complete information about the risks and benefits of using this product.

This product may adversely interact with certain health and medical conditions, other prescription and over-the-counter drugs, foods, or other dietary supplements. This product may be unsafe when used before surgery or other medical procedures. It is important to fully inform your doctor about the herbal, vitamins, mineral or any other supplements you are taking before any kind of surgery or medical procedure. With the exception of certain products that are generally recognized as safe in normal quantities, including use of folic acid and prenatal vitamins during pregnancy, this product has not been sufficiently studied to determine whether it is safe to use during pregnancy or nursing or by persons younger than 2 years of age.

Copyright © 2018 Wolters Kluwer Health

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer