L-cysteine has an important role as a building block of glutathione. Glutathione (gamma-glutamylcysteinylglycine) is a tripeptide that participates in a variety of detoxification, transport, and metabolic processes. Glutathione is the most abundant antioxidant within our cells. The balance between its reduced form (often abbreviated GSH) and oxidized form glutathione disulfide (GSSG) maintains the sulfur-hydrogen groups of intercellular proteins in the correct oxidation states for optimum metabolic functions. GSH is also substrate for peroxidase reactions, which destroy reactive peroxide radicals, and is involved in leukotrienes synthesis.
Reactive oxygen metabolites and leukotrienes are the main players in the biochemistry of airway inflammation. They directly cause symptoms of asthma, allergies, and breathing difficulties associated with inhaled toxins.
Leukotrienes
Arachidonic acid is a polyunsaturated fat always present in cell membranes. Inflammatory triggers (i.e. pathogens, allergens) signal enzymes to turn arachidonic acid into a series of very troublesome leukotrienes. This leukotriene series acts to keep inflammatory conditions running once they're initiated. They're also stimulators of bronchial constriction, and increase production of lung mucus. You only need to produce a tiny amount to narrow the breathing passages and precipitate an asthma attack.
Reactive Oxygen Metabolites
Abnormally high levels of leukotrienes and reactive oxygen metabolites (ROM) are responsible for chronic bronchial and lung inflammation. Most ROM are naturally produced by activated immune cells, increased metabolism, and strenous exercise, as well as in response to tissue injury. They are part of our defense and repair mechanisms, but they're also capable of irritating and inflaming tissues all over the body. Prolonged or chronically high ROM levels are not beneficial - ROM begin to damage instead of repairing tissues. Excessive levels of ROM are also caused by external agents including tobacco smoke, toxic chemicals, and mining or agricultural dust.
