Gum tragacanth
A natural plant gum used to thicken and stabilise foods. Approved in the UK and EU, but documented as a potent allergen in sensitive individuals.
Documented as a powerful allergen capable of triggering asthma, contact dermatitis, and severe allergic reactions including anaphylaxis in sensitised people. Cross-reactivity with gum arabic has been reported.
What is it?
Tragacanth is a viscous gum obtained from the dried sap of Astragalus shrubs, mainly Astragalus gummifer, native to the Middle East and western Asia. It is one of the oldest known natural gums and consists primarily of a complex polysaccharide mixture (tragacanthin and bassorin fractions).
What does it do?
It absorbs water to form a thick, stable gel, making it effective as a thickener, emulsifier, stabiliser and binder. It resists heat and acidic conditions better than many other natural gums, which makes it useful in products where stability is needed over a wide pH range.
Where you will see it
Found in salad dressings, sauces, confectionery, ice cream, baked goods, pie fillings, and pharmaceutical tablet coatings. Historically common in confectionery gums and pastilles. On a UK label it appears as 'gum tragacanth' or 'E413'.
What the science says
Allergy and severe hypersensitivity reactions
Gum tragacanth has been documented as a potent allergen since at least the mid-twentieth century. Case reports describe asthma, rhinitis, contact dermatitis, and anaphylactic-type reactions following exposure. Sensitisation is most commonly reported through occupational inhalation, though food-route reactions have also been described. Cross-reactivity with gum arabic (E414) has been confirmed in laboratory tests, meaning people already allergic to gum arabic may react to E413.
An early clinical case established that tragacanth is a powerful allergen capable of causing extremely severe reactions, including anaphylaxis, and noted that desensitisation is difficult.
Cross-reactivity between gum arabic and gum tragacanth has been demonstrated by RAST (radioallergosorbent testing), indicating shared allergenic epitopes between the two gums.
Allergic manifestations to tragacanth can occur across the full spectrum of severity, from contact dermatitis through to occupational asthma; reactions are more likely following inhalation exposure.
EFSA re-evaluation and ADI
EFSA completed a systematic re-evaluation of E413 in 2017 and concluded no numerical acceptable daily intake was needed based on reported food-additive use levels. The panel noted the long history of use and low dietary exposure. However, the evaluation did not negate the allergenicity signal, which is separate from the dose-based toxicological assessment.
EFSA concluded that no numerical ADI is required for tragacanth (E413) and identified no safety concern for the general population at reported food-additive exposure levels.
Where it stands with the regulators
Who should be careful
Anyone with a known allergy to plant gums, particularly gum arabic (E414), should be cautious, as cross-reactivity has been documented. People who handle gum tragacanth in powder form occupationally (bakers, food manufacturers, pharmacists) face a higher inhalation-sensitisation risk. Look for 'gum tragacanth' or 'E413' on the ingredient list.
The honest read
Gum tragacanth has been used in food for centuries and has a long regulatory track record. The main documented concern is allergenicity rather than toxicity. Most people consume it without any reaction. However, for a small number of sensitised individuals it can trigger reactions ranging from dermatitis to severe asthma, and there is cross-reactivity with gum arabic. The allergenicity signal is real and well-supported by case literature, even if the population-level risk from food amounts is low. Labelling as E413 is the only current tool a shopper has to identify it.
Related additives
Common questions
Is E413 banned in the UK?
No. Gum tragacanth (E413) is approved for use in both the UK and EU under food additive regulations. EFSA completed a re-evaluation in 2017 and maintained its approved status.
Can gum tragacanth trigger an allergic reaction?
Yes. Tragacanth is a documented allergen. Case reports going back decades describe asthma, contact dermatitis, and severe allergic reactions in sensitised individuals. Cross-reactivity with gum arabic (E414) has also been confirmed in laboratory tests. If you have reacted to gum arabic, tragacanth is a potential cross-reactor.
What foods contain E413?
Gum tragacanth appears in salad dressings, emulsified sauces, ice cream, confectionery (particularly pastilles and gum sweets), baked goods, and some pie fillings. It is also used in pharmaceutical tablet coatings. On a UK label it is listed as 'gum tragacanth' or 'E413'.
Is E413 vegan?
Yes. Gum tragacanth is derived entirely from the dried sap of Astragalus shrubs. It contains no animal-derived ingredients and is suitable for vegans and vegetarians.
Sources
- EFSA Journal: Re-evaluation of tragacanth (E413) as a food additive (2017)
- UK FSA: Approved additives and E numbers
- Journal of Allergy: The allergenic properties of the vegetable gums (1943)
- Thermo Fisher Scientific Allergen Encyclopaedia: Tragacanth gum (f298)
- Frontiers in Immunology: Food-Induced Anaphylaxis: Role of Hidden Allergens and Cofactors (2019)
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