Is L-cysteine (E920 / INS 920) Halal?
L-cysteine is considered haram (not permissible). Amino acid often sourced from human hair or poultry feathers.
Why this status?
Amino acid often sourced from human hair or poultry feathers. Haram unless certified plant/microbial origin.
Editorial summary
This summary is editorial and is general information, not a religious ruling. The status above is unchanged.
What it is
L-cysteine, also listed as E920, L-cystine and cysteine, is an amino acid used as a dough conditioner that makes bread, bagels, pizza bases and other baked goods easier to shape and quicker to prepare. This entry is rated haram unless the source is certified plant or microbial.
Where it comes from
According to the Vegetarian Resource Group, L-cysteine is most often made from human hair or duck feathers and to a lesser extent from pig bristles and hooves. Synthetic versions made by chemical or fermentation processes exist, and their manufacturers say they are certified kosher and halal, but they cost more and are used less. Published Islamic rulings state that products containing L-cysteine from human hair or from pigs are impermissible.
Reading a label
The ingredient list shows L-cysteine or E920 without a source, and manufacturers have often been vague about where theirs comes from. Look for bread, bagels, flatbreads, crackers and pastry that carry a halal certificate, or for products that state that their cysteine is plant-based or fermentation-derived, and ask the manufacturer in writing when they do not. Many breads do not use it at all, so a short ingredient list is a reasonable starting point.
Common products
L-cysteine is used mostly in commercial bread, bagels, pizza dough, flatbreads, pastries and some processed meat and flavorings. Small bakeries and artisan breads often leave it out, since it is mainly used to speed up industrial production. Halal-certified bread brands and bakeries that state their ingredients are the easiest way to avoid the question.
In short
In short, L-cysteine is commonly made from hair, feathers or bristles and is rated haram unless certified plant or microbial. Synthetic versions exist, and the label does not say which a bread uses.
Also listed on labels as
L-cysteine can appear on an ingredient list as E920, L-cystine, cysteine.
What to do when a product lists it
A product that lists this ingredient is not permissible for those who follow this rating, so look for an alternative made without it. Some ingredients have halal-certified or plant-based versions, and a recognized halal certificate is the way to confirm that a particular product uses one. Recipes change and differ between countries, so check the package in your hands.
Sources
Classification based on clinical nutrition assessment; no independent published study cited.
Reviewed by Habib Aman, Islamic Scholar, MBA — last reviewed September 27, 2026.
This is general guidance for everyday shopping, not a religious ruling. Formulations vary by manufacturer and country — confirm with the manufacturer or your local scholar when it matters.
Checking a whole product?
SafaScan is a halal scanner app that is coming soon. It will check L-cysteine and every other ingredient on a product. Sign up for launch updates. Learn about SafaScan.
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