Re: My friend\'s hair has grown like crazy!!!!!....
Caution:
When taking L-cysteine, N-acetyl-cysteine, or glutathione, it is recommended that three times as much vitamin C should be taken at the same time to prevent these amino acids from being oxidized in the body.
L-cysteine is a conditionally essential amino acid, one of only three sulfur-containing amino acids, the others being taurine (which can be produced from L-cysteine) and L-methionine from which L-cysteine can be produced in the body by a multi-step process.
L-cysteine is a protein amino acid naturally present in the proteins of life forms. L-cysteine is a sulfur amino acid and contains a sulfhydryl group. Although most cysteine is found in proteins, small amounts of free cysteine are found in body fluids and in plants. The normal diet contributes approximately 1 gram of L-cysteine daily.
L-cysteine is considered a nonessential amino acid, meaning that, under normal physiologic conditions, sufficient amounts of this amino acid are formed from the dietary essential amino acid L-methionine and the nonessential amino acid L-serine via a transsulfuration reaction. L-cysteine is a conditionally essential amino acid under certain circumstances, for example, for preterm infants.
L-cysteine serves as a precursor for synthesis of proteins, glutathione, taurine, coenzyme A and inorganic sulfate. Glutathionine itself has a number of biochemical functions, including maintenance of normal cellular redox state. Certain conditions, e.g. an acetaminophen overdose, can deplete hepatic glutathione, and this can be life-threatening. The antidote to an acetaminophen overdose is L-cysteine, in the delivery form of N-acetylcysteine. The L-cysteine derived from N-acetylcysteine helps to restore hepatic glutathione.
L-cysteine can act as an antioxidant, may prevent liver diseases, and can help to thicken the individual diameters of existing hair if taken regularly. Following ingestion, some L-cysteine is oxidized to L-cystine, and both L-cysteine and L-cystine are absorbed from the small intestine by active-transport processes. L-cysteine absorption is largely sodium-dependent, while L-cystine is absorbed by a sodium-independent transport system. Following absorption, L-cysteine enters the portal circulation, which distributes it to the liver. There, much of it is metabolized to protein, glutathione, taurine and sulfate. L-cysteine, which does not get metabolized by the liver, enters the systemic circulation which distributes it to various tissues of the body.
Although the incidence of cystine renal stones is low, they do occur. Those who form renal stones, particularly cystine stones, should avoid L-cysteine supplements. L-cysteine, like other sulfhydryl-containing substances, could produce a false-positive result in the nitroprusside test for ketone bodies used in diabetes.
There are no reports of overdosage in those taking L-cysteine supplements. However, large doses of L-cysteine are neuroexcitotoxic in several species. Single injections of L-cysteine (0.6-1.5 g/kg) into 4-day-old pups resulted in massive damage to cortical neurons, permanent retinal dystrophy, atrophy of the brain and hyperactivity.
The usual supplemental dosage of L-cysteine is 500 milligrams to 1.5 grams daily. Those who supplement with L-cysteine should drink at least six to eight glasses of water daily in order to prevent cystine renal stones. Some studies indicate that an intake of 3 to 5 grams daily of vitamin C may prevent cystine stones. However, high-dose vitamin C itself may contribute to renal stones in some (see Vitamin C).
N-acetyl-cysteine is the acetylated form of L-cysteine which is more efficiently absorbed and used. It is also an antioxidant that is helpful against viruses. N-acetyl-cysteine has been used as a liver protectant and to break up pulmonary and bronchial mucus. N-acetyl-cysteine can boost glutathione levels in cells.
Glutathione (gamma-L-glutamyl-L-cysteinyl-glycine) is a peptide (short protein)-like molecule synthesized in the body from the three amino acids L-glutamic acid, L-cysteine, and glycine. Glutathione is one of the body’s most important and powerful antioxidants. A major function of vitamin C is to keep glutathione, L-cysteine, and N-acetyl-cysteine in reduced form so that they can continue to have their powerful free radical quenching effects.
Even though many published studies show that garlic, selenium, alpha-lipoic acid, L-cysteine and N-acetyl-cysteine can boost cellular glutathione levels, people with health problems may benefit from taking high doses of glutamine. Those with cataracts or liver disease may want to take 500 mg a day of this very potent antioxidant.