Acacia Gum

Scientific Name(s): Acacia senegal (L.) Willd. Other species of Acacia have been used in commerce. Family: Fabaceae (beans)

Common Name(s): Acacia gum , acacia vera , 1 Egyptian thorn , 1 gummi africanum , 2 gum Senegal , gummae mimosae , kher , Sudan gum arabic , Somali gum , yellow thorn

Uses

Acacia gum has been used in pharmaceuticals as a demulcent. It is used topically for healing wounds and has been shown to inhibit the growth of periodontic bacteria and the early deposition of plaque.

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Dosing

Gum acacia is usually used to modify the physical properties of foods. It was used in a clinical study of cholesterol reduction at a dose of 15 g per day.

Contraindications

Contraindications have not yet been identified.

Pregnancy/Lactation

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

Interactions

None well documented.

Adverse Reactions

Ingestion may raise serum cholesterol. Various forms of acacia gum can cause allergic reactions, including respiratory problems and skin lesions.

Toxicology

Acacia is essentially nontoxic when ingested.

Botany

The acacia tree ( A. senegal ; syn. with A. verek Guill et Perr.) is a thorny, scraggly tree that grows to heights of about 15 feet. It grows most prolifically in regions of Africa, in particular in the Republic of Sudan. During times of drought, the bark of the tree splits, exuding a sap that dries in small droplets or “tears.” 3 In the past, these hardened sap tears served as the major source of acacia gum, but today commercial acacia gum is derived by tapping trees periodically and collecting the resin semi-mechanically. At least three grades of acacia gum are available commercially and their quality is distinguished by the color and character in the collected tears. 4 There is considerable variation in gum quality depending on whether it is obtained by natural flow secondary to extreme drought, obtained by tapping or induced by the boring of beetles at sites of branch injury. 5 Gums derived from Combretum are readily available at low prices in East and West Africa and are often offered for sale as “gum arabic.” Because there is no toxicologic data supporting the safety of these gums, they are not recognized as food additives by most countries. 6 Similarly, trees of the genus Albizia are often confused with Acacia and should not be used as acacia substitutes. 7

History

Acacia gum has long been used in traditional medicine and in everyday applications. The Egyptians used the material as a glue and as a pain-reliever base. Arabic physicians treated a wide variety of ailments with the gum, resulting in its current name. 3 Today, it is used widely in the pharmaceutical industry as a demulcent and in the cooking industry to give body and texture to processed food products. It also is used to stabilize emulsions. The fibers of the bark are used to make cordage. 8

Chemistry

Acacia gum is a brittle, odorless and generally tasteless material that contains a number of neutral sugars, acids, calcium and other electrolytes. 9 The main component of the gum is arabin, the calcium salt of the polysaccharide arabic acid. 4 The structure of the gum is complex and has not yet been fully explained. A comprehensive analysis, including NMR spectra for 35 samples of gum arabic, has been published to serve as the basis for international standardization of acacia gum. 10 The gum is built upon a backbone of D-galactose units with side chains of D-glucuronic acid with L-rhamnose or L-arabinose terminal units. The molecular weight of the gum is large and estimates suggest the weight lies in the range of 200,000 to 600,000 daltons. 9 It is very soluble in water, but does not dissolve in alcohol.

Uses and Pharmacology

Acacia gum has no significant systemic effects when ingested.

Cholesterol

Although related gums have been shown to be hypocholesterolemic when ingested, there is no evidence for this effect with acacia.

Animal data

Some studies suggest that ingestion of acacia gum may increase serum cholesterol levels in rats. 9

Clinical data

When administered to hypercholesterolemic patients for periods ranging from 4 to 12 weeks, acacia gum had no effect on the level of any plasma lipid evaluated. 11 , 12

Periodontal disease

Whole gum mixtures of acacia have been shown to inhibit the growth of periodontic bacteria, including Porphyromonas gingivalis and Prevotella intermedia in vitro when added to culture medium in concentrations ranging from 0.5% to 1%. 13

Animal data

Research reveals no animal data regarding the use of acacia gum for periodontal disease.

Clinical data

At a concentration of 0.5%, acacia whole gum mixture also inhibited bacterial protease enzymes, suggesting acacia may be useful in limiting the development of periodontal disease. In addition, chewing an acacia-based gum for 7 days has been shown to reduce mean gingival and plaque scores compared to a sugar-free gum; the total differences in these scores was significant ( P < 0.05) between groups suggesting that acacia gum primarily inhibits the early deposition of plaque. 14

Other uses

Acacia gum is a demulcent, and soothes irritated mucous membranes. Consequently, it is used widely in topical preparations to promote wound healing and as a component of cough and some gastrointestinal preparations.

In the past, the gum has been administered intravenously to counteract low blood pressure following surgery and to treat edema associated with nephrosis, but this administration caused renal and liver damage and allergic reactions, and its use was abandoned. 5

Dosage

Gum acacia is usually used to modify the physical properties of foods. It was used in a clinical study of cholesterol reduction at a dose of 15 g per day. 12

Pregnancy/Lactation

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

Interactions

None well documented.

Adverse Reactions

Allergic reactions to the gum and powdered forms of acacia have been reported and include respiratory problems and skin lesions. 9 IV administration causes renal and liver damage.

Toxicology

Acacia is essentially nontoxic when ingested.

Acacia contains a peroxidase enzyme, which is typically destroyed by brief exposure to heat. If not inactivated, this enzyme forms colored complexes with certain amines and phenols and enhances the destruction of many pharmaceutical products including alkaloids and readily oxidizable compounds such as some vitamins. 5 , 9 Acacia gum reduces the antibacterial effectiveness of the preservative methyl-p-hydroxybenzoate against Pseudomonas aeruginosa , presumably by offering physical barrier protection to the microbial cells from the action of the preservative. 15 A trypsin inhibitor also has been identified, but the clinical significance of the presence of this enzyme is not known. 8

Bibliography

1. Meyer JE. The Herbalist . Hammond, IN: Hammond Book Co.; 1934:13.
2. Osol A, Farrar GE Jr., eds. The Dispensatory of the United States of America . 25th ed. Philadelphia, PA: J.B. Lippincott; 1955:1.
3. Dobelis IN, ed. Magic and Medicine of Plants . Pleasantville, NY: Reader's Digest Association, Inc.; 1986.
4. Evans WC. Trease and Evans' Pharmacognosy . 13th ed. London: Bailliere Tindall; 1989.
5. Morton JF. Major medicinal plants . Springfield, IL: C.C. Thomas Publisher; 1977.
6. Anderson DM, Morrison NA. The identification of Combretum gums which are not permitted food additives, II. Food Addit Contam . 1990;7:181-188.
7. Anderson DM, Morrison NA. Identification of Albizia gum exudates which are not permitted food additives. Food Addit Contam . 1990;7:175-180.
8. Duke JA. Handbook of Medicinal Herbs . Boca Raton, FL: CRC Press; 1985.
9. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs, and Cosmetics . New York, NY: J. Wiley and Sons; 1980.
10. Anderson DM, Millar JR, Weiping W. Gum arabic (Acacia senegal): unambiguous identification by 13C-NMR spectroscopy as an adjunct to the Revised JECFA Specification, and the application of 13C-NMR spectra for regulatory/legislative purposes. Food Addit Contam . 1991;8:405-421.
11. Jensen CD, Spiller GA, Gates JE, Miller AF, Whittam JH. The effect of acacia gum and a water-soluble dietary fiber mixture on blood lipids in humans. J Am Coll Nutr . 1993;12:147-154.
12. Haskell WL, Spiller GA, Jensen CD, Ellis BK, Gates JE. Role of water-soluble dietary fiber in the management of elevated plasma cholesterol in healthy subjects. Am J Cardiol . 1992;69:433-439.
13. Clark DT, Gazi MI, Cox SW, Eley BM, Tinsley GF. The effects of Acacia arabica gum on the in vitro growth and protease activities of periodontopathic bacteria. J Clin Periodontol . 1993;20:238-243.
14. Gazi MI. The finding of antiplaque features in Acacia arabica type of chewing gum. J Clin Periodontol . 1991;18:75-77.
15. Kurup TR, Wan LS, Chan LW. Interaction of preservatives with macromolecules: Part I- natural hydrocolloids. Pharm Acta Helv . 1992;67:301-307.

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