Is Cysteine Vegan?
Often from feathers or hair.
Contains or is derived from animal products.
Cysteine profile
Cysteine
- Also known as
- L-cysteine, E920, L-cysteine hydrochloride
- Typical source
- Duck or chicken feathers, human hair (most commercial); synthetic or microbial (less common)
- Source type
- Source-dependent
- Common function
- Dough conditioner — relaxes gluten for softer, faster-processing bread
- Vegan status
- Feather- and hair-derived L-cysteine dominates industrial supply; synthetic exists
- E-number
- E920
Detailed answer
Often not vegan in commercial bread. L-cysteine (E920) is a dough conditioner commonly extracted from duck feathers or human hair, though synthetic and fermented versions exist.
Why the answer varies
L-cysteine is an amino acid added to commercial dough to reduce mixing time and create a softer crumb. The global supply chain is dominated by extraction from duck feathers and, to a lesser extent, human hair collected from barbershops — primarily in Asia. Synthetic L-cysteine exists and is vegan, as do newer microbial fermentation routes. But cost pressures mean feather-derived cysteine remains the default for large bakeries. Labels list it as L-cysteine, L-cysteine hydrochloride, or E920 without noting the origin.
Products that commonly contain L-cysteine
- Supermarket sliced white and whole wheat bread
- Bagels, burger buns, and hot dog rolls
- Frozen pizza dough and some fresh pizza bases
- Crackers and certain pretzel products
- Some hair-care products (different supply chain, same ingredient name)
L-cysteine production routes
| Source | Vegan? | Market share |
|---|---|---|
| Duck/chicken feathers | No | Majority of food-grade supply |
| Human hair | No | Significant, especially in Asia |
| Synthetic (petrochemical) | Yes | Growing but minority |
| Microbial fermentation | Yes | Emerging, used by some vegan brands |
How to avoid non-vegan L-cysteine
- Read bread labels for L-cysteine, L-cysteine hydrochloride, or E920.
- Choose bread labeled vegan — certifiers require plant or synthetic sources.
- Artisan, bakery-fresh, or simple-ingredient breads (flour, water, yeast, salt) usually skip dough conditioners.
- Supermarket in-store bakery bread sometimes has shorter ingredient lists — compare loaves side by side.
- Ask your local bakery directly; smaller operations often know their ingredient sources.
Frequently asked questions
- Is E920 always from duck feathers?
- Not always, but feather extraction is the dominant commercial method. Synthetic and fermented alternatives exist but are not the default for mass-market bread.
- Is L-cysteine in hair products the same as in bread?
- Same chemical compound, potentially different supply chains. Neither feather- nor hair-derived cysteine is vegan.
- Do all commercial breads contain L-cysteine?
- No, but it is very common in soft, shelf-stable sliced bread. Crusty artisan loaves and many European-style breads omit it.
- Is synthetic L-cysteine vegan?
- Yes. Synthetic L-cysteine is produced without animal inputs. The challenge is knowing which bread uses it.
- Is L-cysteine the same as cystine?
- Related but not identical — cystine is the oxidized dimer of cysteine. Both can appear in supplements; source questions apply to both.
- Are bagels usually vegan aside from L-cysteine?
- Many bagels are otherwise vegan (flour, water, yeast, malt), but commercial bagels frequently include E920. Check each brand.
Evidence
Last verified August 2026
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Checked by Is This Vegan? · August 2026