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N-acetyl-cysteine (NAC) is the acetylated form of L-cysteine that has been used to break up pulmonary and bronchial mucous.86-94 It is very efficiently absorbed and has been shown to protect cells directly.95-104 NAC is an antioxidant and a free radical-scavenging agent that increases intracellular glutathione at the cellular level. NAC can act as a precursor for glutathione synthesis as well as a stimulator of the cytosolic enzymes involved in glutathione regeneration. NAC has been shown to protect against oxidative stress-induced neuronal death in cultured granule neurons.105

NAC is an antioxidant that increases intracellular glutathione at the cellular level. NAC can act as a precursor for glutathione synthesis as well as a stimulator of the cytosolic enzymes involved in glutathione regeneration. NAC is the more efficiently absorbed and used form of the amino acid L-cysteine. L-cysteine plays a role in the sulfation cycle, acting as a sulfur donor16 in phase II detoxification and as a methyl donor in the conversion of homocysteine to methionine.17,18 N-acetyl cysteine also enhances immune function.19-22 NAC attenuates the progression of the abnormal retention of lipids within liver cells by decreasing development of oxidative stress and subsequent increases in TNF-alpha.23 In addition, N-acetyl cysteine is used to support bronchial health.24-27

Those who supplement with NAC should drink six to eight glasses of water daily to prevent cysteine renal stones. Cysteine renal stones are rare but do occur.