Immune Life

Cysteine and Cystine

The names sound similar, but they describe different chemical forms.

Cysteine

Cysteine is a sulfur-containing amino acid used to build proteins and glutathione. Its sulfhydryl group gives it important chemical reactivity.

Cystine

Cystine forms when two cysteine molecules are linked by a disulfide bond. Under the right conditions, cells can convert cystine back into cysteine.

Food and supplements

Protein-rich foods provide amino acids, while some whey products contain cystine-rich proteins. Processing conditions can change protein structure, so product quality and evidence matter.

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