L-cysteine
Learn what L-cysteine (E920) is, why it's added to food, whether it's safe, and which products contain it.
Generally recognized as safeWhat is L-cysteine?
A food additive used as a flour improver. L-cysteine is a non-essential amino acid (the human body produces it naturally and does not rely on external sources). Higher amounts are beneficial and necessary for children and the elderly. It plays an important role in detoxifying the body, particularly from smoking or alcohol consumption. L-cysteine is derived from animal proteins, hair (animal or human), and feathers. It is added to bread flour to improve dough quality, ease processing, and stabilize bread structure.
Why is L-cysteine added to food?
L-cysteine (E920) is a flour treatment agent commonly found in: Bakery products.
Permitted quantity: No daily limit specified.
Is L-cysteine safe?
Generally recognized as safe
No side effects have been reported at levels found in food.
Is L-cysteine banned anywhere?
✓ Not currently banned in the EU or known to be restricted in other countries.
Is L-cysteine okay for kids?
This additive is not permitted in foods intended for infants and young children.
Common foods that contain L-cysteine
- Bakery products
How to spot L-cysteine on labels
Look for any of these names in the ingredients list:
- E920
- L-cysteine
Common misspellings to watch for:
- l-eysteine
- l-cysteine
- l-cy$teine
- l-cystelne
Better alternatives
• Renal conditions: L-cysteine is metabolized in the kidneys. Individuals with renal impairments should avoid excessive consumption as it may strain the kidneys. • Liver conditions: High intake of L-cysteine can add pressure on the liver, especially in individuals with pre-existing liver conditions. Medical consultation is recommended for such individuals before consuming L-cysteine supplements.
Also known as
- l-eysteine
- l-cysteine
- l-cy$teine
- l-cystelne
Scan products with BioBrief
Not sure if a product contains L-cysteine? BioBrief scans the barcode and instantly shows you every additive in the ingredients list — including E920 — with a plain-language explanation.
Frequently asked questions about L-cysteine
- Is L-cysteine safe to eat?
- No side effects have been reported at levels found in food.
- Is L-cysteine banned anywhere?
- L-cysteine is not currently banned in the EU or known to be restricted in other countries.
- Is L-cysteine safe for children?
- This additive is not permitted in foods intended for infants and young children.
- How do I spot L-cysteine on a food label?
- Look for E920, L-cysteine in the ingredients list. It may also appear as: l-eysteine, l-cysteine, l-cy$teine.
Ingredients change. Always check the actual product label before purchasing. Information on this page is for educational purposes only.