There’s a lot of cystine in alpha-keratin, the protein that makes up the fingernails, skin, and hair. For this reason cysteine supplements are sometimes marketed as anti-ageing products that claim to stimulate the formation of collagen and improve skin elasticity. Cysteine supplementation may also help speed the healing of burns and wounds, and improve joint flexibility in those with rheumatoid arthritis.
Because it promotes the production of the antioxidant glutathione, cysteine supplementation may be useful to those suffering from conditions that have been linked to free-radical oxidative damage, such as hardening of the arteries and cancer. It may also help treat emphysema, tuberculosis, and bronchitis—cysteine has been shown to help break down mucus in the respiratory tract.
Cystine is a nonessential amino acid, which means the body manufactures its own supply of this substance.
The body more easily absorbs cysteine than cystine, so most supplements contain cysteine rather than cystine. In addition, too much cystine in the body can cause cystinosis, a rare disease that can cause cystine crystals to form in the body and produce bladder or kidney stones. This side effect has not been associated with cysteine; however, as previously mentioned, cysteine is unstable, and is often converted to cystine in the body. To avoid the conversion of cysteine to potentially harmful amounts of cystine, it is advised to take vitamin C supplements or consume citrus fruits along with cysteine supplements. The body without adequate amounts of vitamin B6, vitamin B12 and folic acid cannot use cystine, so you’ll want to make sure you get the right amount of these supplements as well. B vitamins are also needed to help the body get rid of homocysteine, a waste product that is formed when the body uses cysteine. Homocysteine has been linked to inflammation in the arteries that results in heart disease.
Cysteine is a powerful free radical destroyer by itself, but works best when vitamin E and selenium are present. It helps detoxify and protect the body from radiation damage, so it is often used in conjunction with chemotherapy and radiation cancer treatments.
Sources of cysteine
Cysteine can be synthesize from the amino acid methionine in our body but is also found in high protein foods such as poultry, wheat, broccoli, eggs as well as garlic, onions and red peppers.
Benefits of cysteine
Cysteine is required by our skin as well as to detoxify our body. It is found in beta-keratin, the main protein in nails, skin as well as hair. It not only is important in collagen production but also assists in skin elasticity and texture.
Cysteine is also required in the manufacture of the amino acid taurine and is a component of the antioxidant gluthione. It is useful to detoxify the body from harmful toxins and help protect the brain and liver from damage from alcohol, drugs etc.
It has also been found that it may help in strengthening the protective lining of the stomach as well as intestines, which may help prevent damage caused by aspirin and similar drugs.
Cysteine is also critical to the metabolism of a number of essential biochemicals including coenzyme A, heparin, biotin, lipoid acid, and glutathione.
Benefits of cystine
Required for proper vitamin B6 utilization and is also helpful in the healing of burns and wounds, breaking down mucus deposits in illnesses such as bronchitis as well as cystic fibrosis.
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 etc.
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.
Deficiency of cysteine
No important deficiency symptoms are known. In chronic diseases it appears that the formation of cysteine from methionine is prevented, resulting in a deficiency.
Symptoms of high intake
People suffering from diabetes should be careful when taking supplementation, as it could inactivate insulin.
People suffering from AIDS/HIV may benefit from cysteine in proper amounts, as low levels are normally reported in people with this problem.
General daily requirement is not known but as supplement cysteine is used at 200 mg two to three times per day.