Is L-cysteine (E920) vegan?
Depends on the brand
Depends — L-cysteine dough conditioner can come from duck feathers, hog hair or fermentation.
Also listed as: E920, cystine
Key facts
- Verdict
- Depends on the brand
- Category
- Additive
- Also listed as
- E920, cystine
- Best swap
- Sourdough breads
Why
The amino acid is used to soften commercial bread and pastry. Traditional production used feathers and hair; synthetic and microbial fermentation versions are now common but rarely labelled.
What to check on the label
- E920 in supermarket bread and buns
- Fast-food bakery items
- Brand confirmation of synthetic source
Swap it for
Sourdough breadsHome-baked or artisan loavesCertified vegan bakery brands
Questions people ask
Is bread usually vegan?
Plain bread often is, but soft supermarket buns may contain L-cysteine, whey, honey or mono- and diglycerides.
Can I tell from the label?
Rarely — only a vegan certification or a direct answer from the manufacturer confirms the source.
More additive checks
Reviewed 2026-09-16 by the Veg.ac editorial team · Free to reuse under CC BY 4.0 with a link back.