Tragacanth gum is a food additive which may result in allergy symptoms in sensitised individuals.

Tragacanth Gum Allergy Test: Allergen Exposure

Tragacanth gum is a viscous, odorless, tasteless, water-soluble mixture of polysaccharides obtained from sap and dried.

The sap is collected from the Astragalus species of shrub, an evergreen growing to 30cm in height, which is found in Iran, Asia Minor and Syria. Tragacanth is collected via man-made incisions in the lower stem and root of the shrub, and is similar in this fashion to the collection of latex. It is considered to be the most viscous of the naturally occurring plant gums. Tragacanth gum has been collected and used by humans for many thousands of years.

Tragacanth gum is used as a thickener, stabiliser and emulsifier in candy, salad dressings, sauces, fruit jelly, ornamental icings, fruit sherbets, etc. It is an approved additive to food and has the E number E413. The seedpods of some species may be eaten, but those of others are toxic.

The gum is demulcent, though it is not often used internally because it is not completely soluble. It has long been employed externally as a dressing for burns. This gum has recently been shown to stimulate the immune system and to suppress tumours. Tragacanth tends to decrease absorption of cholesterol into the system if taken with cholesterol-rich foods.

It also has a wide range of non-food uses, including as a thickener, stabiliser and emulsifier in shaving cream, toothpaste, face packs, creams, and eye makeup, as a fabric dressing, and as a thickening agent in dyes, glues, watercolours and ink.

It has been used in traditional medicine as a herbal remedy for conditions such as coughs and diarrhea, as well as a topical treatment for superficial burns.

Being highly water soluble, it is ideal for ease of use and even spreading, and it is one of the stronger naturally occurring plant gums for holding particles in suspension. Smaller amounts of tragacanth gum are needed, when compared to gum arabic or similar substances, for the same applications.

It is used as a binding agent in paper making, and a culture medium in laboratories. It is commonly used in lozenges in order to bind the ingredients and impart consistency, as well as in cigar making to seal and secure the outer tobacco skin.

Both the stems and the gum can be burnt as incense.

Tragacanth Gum Allergy Test: Allergen Description

No allergens from tragacanth gum have yet been characterised.

Tragacanth Gum Allergy Test: Potential Cross-Reactivity

An extensive cross-reactivity among the different individual species of the genus could be expected but in fact is not seen frequently.

Clinical studies have found that there is little cross-reactivity among members of the Fabaceae (Leguminosae).

Cross-reactivity between Acacia gum and Tragacanth gum has been reported.

Tragacanth Gum Allergy Test: Clinical Experience

Tragacanth gum may rarely induce allergy symptoms in sensitised individuals. Asthma and contact dermatitis have been described. Excess ingestion can result in diarrhoea, abdominal pain, gas production or constipation.

Other reactions

Many members of this genus contain toxic glycosides. All species with edible seedpods can be distinguished by their fleshy round or oval seedpod that looks similar to a greengage.

A number of species can also accumulate toxic levels of selenium when grown in soils that are relatively rich in that element.