L-cysteine is mostly made from human hair, chicken or duck feathers, boar bristles etc., or it can be synthetic. I would like to know if it is halal, since it can be found in many bakery products such as bread, pizza dough, bagels, donuts etc.

  • Do you want to edit the question to mean L-cysteine derived from animal sources? (those animals that are not halal for us to consume, either inherently or because of their manner of slaughter)
    – Ansari
    Commented Jul 1, 2012 at 16:54
  • Yes, I meant the human/animal sources, and I've made the edit.
    – shoehada
    Commented Jul 2, 2012 at 18:41
  • 1
    FYI, if the quantity is sufficiently small, it will not affect the halality of the product. Let me know if you want me to post an answer detailing this.
    – ashes999
    Commented Jul 4, 2012 at 16:32

2 Answers 2


Is L-cysteine halal?

Yes, it is.

What is L-cystiene?

Cysteine (abbreviated as Cys or C)[3] is an α-amino acid with the chemical formula HO2CCH(NH2)CH2SH. It is a semi-essential amino acid, which means that it can be biosynthesized in humans.
P.S Biosynthesized meansthe following - Biosynthesis (also called biogenesis) is an enzyme-catalyzed process in cells of living organisms by which substrates are converted to more complex products.
or in brief it is produced in our body (this is one proof that it is halal).Cysteine can usually be synthesized by the human body under normal physiological conditions if a sufficient quantity of methionine is available. Cysteine is catabolized in the gastrointestinal tract and blood plasma.

Where is is used? Where is it found?

Although classified as a non-essential amino acid, in rare cases, cysteine may be essential for infants, the elderly, and individuals with certain metabolic disease or who suffer from malabsorption syndromes. (2nd proof of being halal)

Cysteine is found in most high-protein foods, including:

Animal sources:- Sausage meat, chicken, turkey, duck, luncheon meat, eggs, milk, whey protein, ricotta, cottage cheese, yogurt.

Plant sources:- Red peppers, garlic, onions, broccoli, brussels sprout, oats, granola, wheat germ. (3rd proof of being halal. As these food stuff are halal and they occur naturally in these foods then it has to be halal.)

Note- Im not a biology student so this information is not from me but from wikipedia.
Another thing to note is that L-cystiene is the same as cystiene. Well actually along with L-cystiene there also exists D-cystiene. They both are same to cystiene. Their chemical properties are similar but their physical properties might not be similar. i know this because i am a chemistry student.

  • 2
    Just because our body produces it doesn't mean it's a proof for being halal :) Our body produces lots of other things that are unlawful for consumption.
    – Ansari
    Commented Jul 1, 2012 at 16:55
  • @Ansari i know you might be thinking of urine etc. but i meant that it is produced to be used as a nutrient
    – Ashu
    Commented Jul 1, 2012 at 16:58
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    Point taken - but I suspect the question is more about the sources of the L-cysteine than the compound itself. I asked the OP to clarify.
    – Ansari
    Commented Jul 1, 2012 at 17:00
  • @Ansari i think OP is confused between natural and man-made sources
    – Ashu
    Commented Jul 1, 2012 at 17:02
  • 3
    This doesn't really answer my question. Most of the L-cysteine that is used in bakery products is either made from human hair or chicken/duck feathers etc. (naturalnews.com/032718_L-cysteine_commercial_bread.html) I just wanted to know what's the ruling of L-cysteine from these sources.
    – shoehada
    Commented Jul 2, 2012 at 18:43

Well muslim consumer group declares the following The L-Cysteine made from human hair is a Haram ingredient. The L-Cystiene made from chicken/duck feathers is not consider as Halal by ulema. July 2014

  • It would be useful to add your resource here
    – nim
    Commented Feb 5, 2016 at 8:52

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