Cysteine and cystine - Nature Cures®

Cysteine is a sulphur containing amino acid that occurs naturally in foods and can also be manufactured by the body from the amino acid methionine. In the production of cysteine, methionine is converted to S-adenosyl methionine, which is then converted to homocysteine. Homocysteine then reacts with serine to form cysteine.

Cysteine is also found in the body and in food as cystine, an amino acid that contains two cysteines joined together. Cysteine is the precursor for proteins, glutathione, taurine, coenzyme A and inorganic sulphate.

Glutathione, glutamic acid and glycine, is found in all human tissues, with the highest concentrations in the liver and eyes. Glutathione is a potent antioxidant, protecting fatty tissues from the damaging effects of free radicals. The antioxidant activity of glutathione is attributed specifically to the presence of cysteine in the compound.

Cysteine rich foods can help to detoxify the body of chemicals and heavy metals and protect cells from free radical damage. Because it can breakdown proteins found in mucous that settles in the lungs it can be useful in the treatment of many respiratory problems.

Conditions that cysteine can prevent and help to treat

Acute respiratory distress syndrome
Asthma
Bronchitis
Cancer
Cataracts
Coughs and colds
Cystic fibrosis
Dementia
Hair loss
Heart disease
Heavy metal toxicity or exposure
HIV/AIDS
Liver disease
Parkinson’s disease
Psoriasis
Rheumatoid arthritis
Viral infections

Deficiency of cysteine

Deficiency is relatively uncommon but may be seen in vegetarians with low intake of the plant foods containing methionine and cysteine. Low cysteine levels may reduce one’s ability to prevent free radical damage and may result in impaired function of the immune system and neurodegenerative diseases, including multiple sclerosis, amylotrophic lateral sclerosis (Lou Gehrig’s disease) and Alzheimer’s disease.

Because the production of cysteine involves several nutrients a deficiency of methionine, vitamin B6 (pyridoxine), vitamin B9 (folate), vitamin B12 (cyanocobalamin) and s-adenosyl methionine (SAMe) may decrease the production of cysteine. Certain medications and alcohol consumption can cause deficiencies of these nutrients which will in turn cause a deficiency in cysteine.

It is scientifically recommended that all individuals 1 years of age or greater should consume 25 milligrams of cysteine plus methionine (combined) for every 1 gram of food protein.

Cysteine often gets destroyed in the gastrointestinal tract as a potentially toxic free molecule. Cystine is used to survive the GI Tract or blood serum and get into the cells that can break the bisulphide bond to utilise the freed cysteine molecules.

Highest sources of cystine in milligrams per 100 grams

Rabbit (wild) 1243 mg
Soya beans 1046 mg
Sesame seeds 1012 mg
Pheasant 1007 mg
Sunflower seeds 952 mg
Chlorella (dried) 770 mg
Safflower seeds 685 mg
Mustard seeds 680 mg
Spirulina (dried) 662 mg
Oat bran 576 mg
Winged beans 545 mg
Calf’s liver 490 mg
Black walnuts 462 mg
Sunflower seeds 451 mg
Watermelon seeds 438 mg
Peanuts 433 mg
Pumpkin and squash seeds 404 mg
Chicken 397 mg
Quail 394 mg
Caviar (fish roe) 389 mg
Peanuts 375 mg
Whelks 374 mg
Brazil nuts 367 mg
Sesame seeds 358 mg
Flaxseeds 340 mg
Lamb’s liver 320 mg
Wheat 317 mg
Mussels 312 mg
Pine nuts 289 mg
Beef (lean mince) 278 mg
Rabbit (wild) 274 mg
Eggs 272 mg
Soya beans 268 mg
Mackerel (tinned) 249 mg
Salmon (Atlantic farmed) 237 mg
Black beans 235 mg
Shrimp/prawns 234 mg
Walnuts 209 mg
Squid 204 mg
Quinoa 203 mg
Venison 202 mg
Almonds 189 mg
Turkey 178 mg
Cheddar cheese 125 mg
Brown rice 96 mg

Related subjects

Join our mailing list to receive your monthly emailed newsletter with all the latest scientific findings for natural health remedies.