Facts
Why cysteine is good for you
Cysteine is a sulphur containing non-essential amino acid, which is formed from methionine. It is necessary in the detoxification of the body from harmful toxins.
Cysteine helps protect the liver and brain from damage. It is required in the manufacture of taurine and is a component of glutathione. Skin nails and hair contain cysteine – and it is not only important in collagen production but also assists in skin elasticity and texture.
Important cysteine facts
- Cysteine is closely related to cystine, as cystine consists of two cysteine molecules joined together
- Cysteine is an unstable nutrient and easily converts to cystine, but this does not cause a problem, since both can convert into the other – as required by the body
- Cysteine is critical to the metabolism of a number of essential biochemicals – coenzyme A, heparin, biotin, lipoid acid, and glutathione
- Cystine or the N-acetyl form of cysteine (N-acetyl cysteine) may be used in place of L-cysteine
- N-acetyl cysteine has been shown to be more effective at boosting glutathione levels than supplements of cystine or even of glutathione itself
Cysteine works best with
Health
Cysteine and health
- Stomach protection – cysteine has been found to help strengthen the protective lining of the stomach as well as intestines, which may help prevent damage caused by aspirin and similar drugs
- Chemotherapy treatment – N-acetyl cysteine helps to prevent side effects from chemotherapy and radiation therapy
Talk to a medical professional about cysteine supplements before taking them.
Deficiency
Groups at risk of cysteine deficiency
Deficiency of cysteine is rare, but can occur in the following individuals:
- People on low protein diets – people who are not eating enough protein foods may not get enough cysteine in their diet
- Vegans and vegetarians – people who are on a strict vegetarian diet may suffer from a cysteine deficiency if their diet is deficient in protein
- HIV and AIDS patients – People suffering from HIV/AIDS may benefit from cysteine in medically administered dosages, as low levels are normally reported in HIV/AIDS patients
People in these groups at risk of cysteine deficiency should talk to a medical professional about cysteine supplementation before trying it.
Symptoms of cysteine deficiency
No direct deficiencies have been reported, but in chronic diseases it seems the formation of cysteine from methionine by the body can be prevented, resulting in a deficiency.
Food sources
Cysteine in food
The body can create cysteine from the amino acid methionine, so there is unlikely to be a deficiency in this amino acid. It is also found in high protein foods such as:
Daily intake
Cysteine recommended daily intake (RDI)
| RDA | No information available |
|---|---|
| TOLERABLE UPPER LIMIT | 200-500mg Must be taken with Vitamin C & Vitamin B6 |
| TOXIC LEVELS | No information available |
Toxicity
Overdosage, toxicity and cautions for cysteine
None known, but damage to nerve cells in rats has been reported in very high dosage, and research data is still not available.
Precautions
Precautions
- People with diabetes should be careful when taking cysteine supplements, as it could inactivate insulin
- Cystinuria patients should not take it.
Interactions
Interactions
References
References
- Osiecki H, Meeke F, Smith J, The Encyclopaedia of Clinical Nutrition – Volume 1: The Nervous System, BioConceps Publishing QLD 2004
Last reviewed and updated: 8 May 2024
