Other name(s):

di-[a-amino-propionic]-b-disulphide, cysteine

Unsubstantiated claims

There may be benefits that have not yet been proven through research.

Cystine may help speed recovery after surgery. It may also boost your immune system. It may also help treat lung diseases.

Recommended intake

Cystine is an amino acid that is found in digestive enzymes, in the cells of the immune system, in skeletal and connective tissues, skin, and hair. Hair and skin are 10% to 14% cystine. Amino acids (AAs) are available as single AAs or in AA combinations. They also come as part of multivitamins, proteins, and food supplements. The forms include tablets, fluids, and powders.

Note that by eating enough protein in your diet, you get all of the amino acids you need.

There are no conditions that increase how much cystine you need.

Side effects, toxicity, and interactions

Using a single amino acid supplement may lead to negative nitrogen balance. This can decrease how efficient your metabolism is. It can also make your kidneys work harder. In children, taking single amino acid supplements may also cause growth problems.

You should not take high doses of single amino acids for long periods of time.

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

People with maple syrup urine disease (MSUD) or cystinuria shouldn’t use cystine supplements.