Other name(s):


Unsubstantiated claims

Please note that this section reports on claims that have NOT yet been substantiated through scientific studies.

Cystine is believed to help speed post-operative recovery and to stimulate the immune system. It may also be useful in treating bronchitis.

It also may play a role in cystic fibrosis, angina, fibrosing alveolitis, chronic obstructive pulmonary disease (COPD), end-stage renal disease (ESRD), epilepsy, and influenza.

Recommended intake

Amino acids (AAs) are available as individual AAs or in proprietary AA combinations, as well as part of multi-vitamin formulas, proteins, and food supplements. The forms include tablets, fluids, and powders. However, adequate protein in the diet should provide a sufficient source of all amino acids.

There are no conditions that increase the nutritional requirements for cystine.

Side effects, toxicity, and interactions

The use of a single amino acid supplement may lead to negative nitrogen balance, decreasing the metabolic efficiency and increasing the workload of the kidneys. In children, taking single amino acid supplements may also harmfully affect growth parameters.

Always avoid taking individual amino acids in high dosage for prolonged periods.

Women who are pregnant or breastfeeding should not use cystine supplements.

Individuals with maple syrup urine disease (MSUD) or cystinuria, rare, inherited disorders, should also not use cystine supplements.

Additional information

Click here for a list of reputable websites with general information on nutrition.