What is Cystine

Chemical Name: 3,3′-disulfanediylbis[(2R)-2-aminopropanoic acid]

Molecular Weight: 240.3

Structrual Formula:

Nitrogen Content: 11.66%


Cystine (13, 117)

  • Cystine is a crystalline, sulfur-containing amino acid, formed from two molecules of the amino acid cysteine
  • It can be converted to cysteine by reduction
  • It is particularly abundant in skeletal and connective tissues, hair and digestive enzymes
  • The steps followed in the formation of cystine and cysteine, is from methionine to cystathionine and then to cysteine to cystine
  • Required for proper vitamin B6 utilization
  • Helpful in the healing of burns and wounds, breaking down mucus deposits in illnesses such as bronchitis as well as cystic fibrosis
  • Cysteine also assists in the supply of insulin to the pancreas, which is needed for the assimilation of sugars and starches
  • It increases the level of glutathione in the lungs, liver, kidneys and bone marrow, and this may have an anti-aging effect on the body by reducing age-spots
  • It has been shown as a detoxification agent to protect the body against damage of alcohol and cigarette smoking, and may be effective in preventing hangovers, as well as preventing liver and brain damage

Cystine and immune system (127)

Cystine provides resistance to the body against harmful effects by building up white blood-cell activity and it is essential for the proper functioning of the skin and helps in recovery from surgery

Cystine and growth (136)

  • It promotes the formation of carotene which helps hair growth
  • The flexibility of the skin, as well as the texture, is influenced by cysteine as it has the ability to protect collagen, the connective tissue protein

Cystine, smoking and alcohol (137)

  • Cystine has been shown to protect the body against damage caused by alcohol and cigarette smoking
  • One report states that not only is it effective in preventing the side-effects of drinking, such as a hangover, but it prevents liver and brain damage as well
  • It also reduces lung damage such as emphysema, resulting from smoking

Cystine in Food

Cystine can be found in whole grains, soya beans, leafy vegetables, Pistachio nuts, bananas, meat, eggs and milk

Deficiency of cystine (61)

In chronic diseases it appears that the formation of cysteine from methionine is prevented, resulting in a deficiency

Toxicity and symptoms of high intake (61)

People suffering from diabetes should be careful when taking supplementation, as it could inactivate insulin

Precaution (61)

  • Accumulation of free cystine in the body tissues can lead to a rare disease known as cystinosis
  • This results in the appearance of cystine crystals in the cornea, conjuctiva; bone marrow, lymph nodes, leukocytes, and internal organs
  • Persons with diabetic tendencies should not use large supplemental doses of cysteine except under medical supervision, as it is capable of inactivating insulin by reducing certain disulphidebbrids which determine its structure
  • In order to avoid the conversion of cysteine to cystine, with possible consequences of the formation of kidney or bladder stones, an intake of three times the dose of vitamin C has been suggested to accompany the taking of cysteine supplementally


  • 13) Balch, James, MD, and Phyllis Balch, CNC, Prescription for Nutritional Healing, Avery Pub., 1997.
  • 117) Cynober, L, editor, Amino Acid Metabolism & Therapy in Health & Nutritional Diseases, 1995.
  • 127) Droge W, Eck HP, Gmunder H, Mihm S. Modulation of lymphocyte functions and immune responses by cysteine and cysteine derivatives. Am J Med. 1991 Sep 30;91(3C):140-144.
  • 136) Pohlandt F. Cystine: a semi-essential amino acid in the newborn infant. Acta Paediatr Scand. 1974 Nov;63(6):801-4.
  • 137) Pech-Amsellem MA, Myara I, Storogenko M, Demuth K, Proust A, Moatti N. Enhanced modifications of low-density lipoproteins (LDL) by endothelial cells from smokers: a possible mechanism of smoking-related atherosclerosis. Cardiovasc Res. 1996 Jun;31(6):975-83.
  • 61) Peter J. Garlick. The Nature of Human Hazards Associated with Excessive Intake of Amino Acids. J. Nutr. 2004 134: 1633-1639.