Cystine is a stable form of the amino acid cysteine. The body is capable of converting one to the other as required and in metabolic terms they can be thought of as the same. Both cystine and cysteine are rich in sulphur and can be readily synthesized by the body. Cystine is found abundantly in hair keratin, insulin and certain digestive enzymes.
As a detoxification agent Cystine has been shown to protect the body against damage induced by alcohol and cigarette smoking. One study showed its effectiveness in preventing the side effects of drinking, such as hangover, and that it prevented liver and brain damage as well.
Cystine or cysteine is needed by the body for proper utilization of vitamin B6. The metabolic steps in the formation of these two amino acids is from methionine to cystathionine to cysteine to cystine. In chronic diseases it appears that the formation of cysteine from methionine is prevented.
One element in correction of the biochemistry of the chronic disease could be the restoration of adequate levels of cysteine or cystine. Cysteine is more soluble than cystine and contributes sulphur more readily and thus achieves better results in some patients.
No single nutrient should be seen as curative for any condition. By reducing the body’s absorption of copper, cystine protects against copper toxicity, which has been linked to behavioral problems. It is also found helpful in the healing of burns and wounds, and is used to break down mucus deposits in illnesses such as bronchitis and cystic fibrosis. Cysteine also assists in the supply of insulin to the pancreas, which is needed for the assimilation of sugars and starches. However, supplements of cysteine and cystine are readily utilized carbon sources that may actually enhance Candida growth in its more pathogenic yeast form.