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What is E920 Food Additive?

02/23/2016 adminCategory: Knowledge of Food AdditivesPage Views: 7517

This is part of our ongoing series helping consumers better understand food additives. We translate the food science, explain the food natures, and give you an honest advice, so you can choose the right foods for your family!

E920 food additive is called L-Cysteine, which is a proteinogenic amino acid contributing to building protein and includes the element sulphur. L-cysteine is a semi-essential amino acid. It is manufactured in the body but may be essential for infants and aging population as well as those metabolic disorders. L-cysteine is built directly from the essential amino acid L-methionine, which makes the abundance of L-methionine in the body a critical factor to the body’s supply of L-cysteine.


Applications and Uses of E920 L-Cysteine

Cysteine, mainly the L-enantiomer, is a precursor in the food, pharmaceutical, and personal-care industries. One of the largest applications is the production of flavors. For example, the reaction of cysteine with sugars in a Maillard reaction yields meat flavors. L-Cysteine is also used as a processing aid for baking. In the field of personal care, cysteine is used for permanent wave applications, predominantly in Asia. Again, the cysteine is used for breaking up the disulfide bonds in the hair's keratin.


Food Source of E920 L-Cysteine

Our body makes cysteine from methionine, an essential amino acid. Cysteine is also found in most high-protein foods, including: Ricotta, Cottage cheese, Yogurt, Pork, Sausage meat, Chicken, Turkey, Duck, Lunch meats, Wheat germ, Granola, Oat flakes.

While some L-cysteine is directly synthesized in laboratories, most of it is extracted from a cheap and abundant natural protein source: human hair. The hair is dissolved in acid and L-cysteine is isolated through a chemical process, then packaged and shipped off to commercial bread producers.


Benefits of E920 L-Cysteine

Cysteine plays an important role in the human body due to its specific structure including sulfur and contributes significantly to the general well-being. Especially when the individual has chronic conditions, cataract or arthritis, the appropriate supplementation of this semi-essential amino acid is of great benefits. Also illnesses of the intestines usually increase the needs for L-cysteine, because many nutrients simply cannot be absorbed and get lost as a result of the digestive system being compromised. Environmental factors such as stress or extreme physical strain will also lead to an increased demand in Cysteine.

A very important role of the semi-essential amino acids lies with protein synthesis, meaning the building of proteins. L-cysteine is a natural building block of many important structural proteins in the connective tissue. The body is also able to convert this multifunctional nutrient into Taurine, which is important for the conducting of electric nervous impulses, the digestive as well as the vascular system.


Side Effects of E920 L-Cysteine

L-cysteine is most likely safe when used properly but may cause some unwanted side effects such as nausea, vomiting, diarrhea and constipation. Allergic reactions may also occur and symptoms may include rashes, fever, headache, low blood pressure, headache and drowsiness. There is currently no link to harm of fetus or mother when pregnant; however, L-cysteine should only be taken when pregnant if absolutely necessary and directed by a physician. L-cysteine benefits should be discussed with a physician to determine whether this supplement is appropriate for you.



Mardikian PN, LaRowe SD, Hedden S, Kalivas PW, Malcolm RJ. An open-label trial of N-acetylcysteine for the treatment of cocaine dependence: a pilot study. Prog Neuropsychopharmacol Biol Psychiatry. 2007;31(2):389-394.

Cai J, Nelson KC, Wu M, Sternberg P Jr, Jones DP. Oxidative damage and protection of the RPE. Prog Retin Eye Res. 2000;19(2):205-221.

Lavergne V, Taft RJ, Alewood PF. Cysteine-rich mini-proteins in human biology. Curr Top Med Chem. 2012

Elshorbagy AK, Smith AD, Kozich V, Refsum H. Cysteine and obesity. Obesity (Silver Spring). 2012

Truong TH, Carroll KS. Redox regulation of epidermal growth factor receptor signaling through cysteine oxidation. Biochemistry. 2012


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