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Ingredient dictionary

Thongweed on a food label: allergens, diets and other names

Thongweed is a kind of seaweed. It is not one of the allergens that labels must declare. It is vegan. Open Food Facts finds it in 90 products, most often in fish and seafood.

By Bravoora teamUpdated Sources checked 4 sourcesHow we check

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Does thongweed contain an allergen?

Thongweed is not one of the allergens that food labels must declare in the US, the UK, Europe or the Gulf. Open Food Facts does not link it to an allergen, and Bravoora’s label checker does not read the name as one.

Is thongweed vegan?

Yes. Thongweed is vegan and vegetarian: Open Food Facts records nothing from an animal in it.

VeganFits youNothing from an animal, by the Open Food Facts record.
VegetarianFits youNothing from an animal, by the Open Food Facts record.

A pack can differ from the usual recipe: the app reads the label in your hand.

What other names does thongweed have on a label?

In English thongweed can also read “sea spaghetti”. On European labels it is “spaghetti de mer” in French, “Riementang” in German and “riemwier” in Dutch. The other 2 languages are listed below.

In Englishsea spaghetti
French
spaghetti de mer, Hymanthalia
German
Riementang
Dutch
riemwier
Finnish
merispagetti
Croatian
prašnjak

Which foods contain thongweed?

Open Food Facts lists thongweed in the ingredients of 90 products, most often fish and seafood, ready meals and dressings and sauces. Most of them are sold in France, Germany and Belgium.

  • Fish and seafood37
  • Ready meals8
  • Dressings and sauces5
  • Oily fish4
  • Salty and fatty foods3
  • Beans and pulses2

Products with it, by country of sale: France 80 · Germany 4 · Belgium 2 · United States 2.

Counted on 13 October 2026 from the Open Food Facts product database, which volunteers fill from real packs: it shows where thongweed turns up, not how much of the market it is.

What kind of ingredient is thongweed?

Thongweed is a kind of seaweed.

Bravoora reads this ingredient for everyone you shop for: an allergy or intolerance, a vegan or vegetarian diet, a calorie or protein goal, and the labels on supplements and skincare too. Build a profile · For dietitians, doctors and trainers

Sources

An allergen is stated only when two of three checks agree: the Open Food Facts record, Bravoora’s label checker, and the ingredient’s own name or family (oat flour is oats, a cheese is milk). Every name where they disagree waits for a person to review it.

  1. Open Food Facts: Thongweed
  2. Open Food Facts: ingredients taxonomy (names, family tree, allergen and vegan flags), ODbL
  3. Open Food Facts: product database, 4,535,553 products, read 13 October 2026, ODbL
  4. Wikipedia: Himanthalia elongata

Contains information from Open Food Facts, which is made available here under the Open Database License (ODbL). Read the licence · Download this dictionary’s data · How we check

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