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N-acetylcysteine (NAC)

The effects of aging are influenced by genetic and environmental factors. Reactive oxygen species (ROS) are considered major culprits in aging and disease. ROS are byproducts of energy generation in normal metabolism and increase during infection and inflammation, exercise and stress, overexposure to sunlight and radiation, and exposure to external pollutants such as auto and diesel exhausts, emissions from power plants, cigarette smoke, pesticides, lead from old paint, and asbestos just to name a few.1

When high levels of ROS exist with inadequate antioxidants to neutralize them, oxidative stress increases and exacerbates aging and disease. The consequences of ROS damage depends on the molecules they attack and the body's levels of antioxidants. When the target molecule is DNA, the resulting ROS-induced chemical changes lead to genetic mutations. Oxidation of lipids and proteins injures cell membranes, increases blood vessel frailty, damages immune cells and modifies enzymes.

As people age, internal antioxidant production declines. This paves the way for increased risk for disease and age-related conditions. No matter how healthy, fit or nutrition-conscious an individual has been, bombardment with environmental contaminants provokes the formation of ROS thus producing some degree of oxidative stress. This increases the demand for antioxidants at a time when the body is producing less. Glutathione levels have been shown to decrease with aging, leaving neurons vulnerable to ROS attack and subsequent damage.2 A steady state of oxidative stress exhausts the body's glutathione resources and outpaces its ability to replace them. Depletion of glutathione is compounded by insufficient supply of precursors for glutathione synthesis.3 As glutathione levels decrease and oxidative stress increases, the cell's ability to function progressively declines until it dies.

How does one boost levels of this powerful antioxidant? Glutathione levels cannot be increased by orally ingesting glutathione. This is because glutathione is manufactured inside the cell. The manufacture of glutathione in cells is limited by the concentration of its precursor, cysteine. Products that increase glutathione must provide cysteine. Glutathione levels cannot be increased by ingesting oral cysteine because oral cysteine is potentially toxic and is spontaneously destroyed in the gastrointestinal tract.

N-acetylcysteine is the bioavailable form of cysteine and dramatically increases the body's production of glutathione, the brain's most important scavenger of ROS, also known as free radicals.

References

  1. Monograph: Glutathione, Reduced (GSH). Alternative Medicine Review 2001;6(6):601-607.
  2. Lui R and Choi J. Age-associated decline in Gamma-glutamylcysteine synthetase gene expression in rats. Free Radical Biology Medicine 2000;28:566-574.
  3. Pocernich C et al. In-vivo glutathione elevation against hydroxyl free radical-induced protein oxidation in rat brain. Neurochemistry International 2000;36:185-191.