Safety Facts and Side Effects About L-Cystine

L-Cystine E921 Side Effects

L-Cystine E921 is marketed in nutritional supplements as an anti-oxidant and immune system booster, and has been reported to improve muscle recovery following vigorous exercise and soft tissue recovery following injury or surgery. Though L-Cystine E921 is considered safe, some are convinced it has potentially dangerous health effects.

What Is L-Cystine E921?

L-Cystine E921 is a nonessential amino acid as a natural nutritional additive, flavor modifier, dough strengthening agent, and yeast fermentation agent.

Possible Side Effects of L-Cystine E921

The most common side effects of L-Cystine E921 supplementation include upset stomach, nausea, vomiting, diarrhea, persistent stomach cramps, body aches, headache, and general gastrointestinal discomfort.

GRAS Affirmation: No

Generally recognized as safe (GRAS) is an American Food and Drug Administration (FDA) designation that a chemical or substance added to food is considered safe by experts, and so is exempted from the usual Federal Food, Drug, and Cosmetic Act (FFDCA) food additive tolerance requirements. Though L-Cystine Side Effects is not on FDA’s GRAS exemption list, it’s still widely accepted as safe food additive in many countries including USA with specific limit on dosage.

Suggested Dosage


Special Populations Precaution

There is a lot of concern about diet and nutrition for these population, like Newborns, children, pregnant, sensitive to L-Cystine populations. Better consult to your doctor if you would like to intake Wild Yam Extract.

Related Research

1. Glutathione and l-cysteine modified silver nanoplates-based colorimetric assay for a simple, fast, sensitive and selective determination of nickel. [Talanta. 2014 Oct] Author: Kiatkumjorn T, Rattanarat P, Siangproh W, Chailapakul O, Praphairaksit N.

2. Potential Protective Effect of l-Cysteine against the Toxicity of Acrylamide and Furan in Exposed Xenopus laevis Embryos: An Interaction Study. [J Agric Food Chem. 2014 Jul 23.] Author: Williams JR, Rayburn JR, Cline GR, Sauterer R, Friedman M.

3. Hydrogen sulfide-mediated regulation of contractility in the mouse ileum with electrical stimulation: Roles of l-cysteine, cystathionine β-synthase, and K+ channels. [Eur J Pharmacol. 2014 Jul 5] Author: Yamane S, Kanno T, Nakamura H, Fujino H, Murayama T.

4. Vitamin D and L-cysteine levels correlate positively with GSH and negatively with insulin resistance levels in the blood of type 2 diabetic patients. [Eur J Clin Nutr. 2014 Jun 25] Author: Jain SK, Micinski D, Huning L, Kahlon G, Bass PF, Levine SN.

5. Structural, morphological and optical studies of l-cysteine modified silver nanoparticles and its application as a probe for the selective colorimetric detection of Hg(2+). [Spectrochim Acta A Mol Biomol Spectrosc. 2014 Dec 10] Author: Nidya M, Umadevi M, Rajkumar BJ.

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