Reactive Oxygen Species (ROS), more simply known as oxidants, are the widely recognized culprits responsible for the functional decline of the mitochondria during aging (mitochondria are the organelles that power all of our cells, except red blood cells). In a recent animal study, scientists demonstrated that by restricting the caloric content of the diet of laboratory animals, and by giving them the amino acid N-acetyl-L-cysteine or NAC, they could counteract both ROS generation and effects during aging. In essence, old mitochondria were converted to young ones. To learn more about this research, click here. "Effect of Antioxidant Diets on Mitochondrial Gene Expression in Rat Brain During Aging" Neurochemical Research, Volume 30, Nos 6/7, June/July 2005, pp. 737-752. This Research Update column highlights articles related to recent scientific inquiry into the process of human aging. It is not intended to promote any specific ingredient, regimen, or use and should not be construed as evidence of the safety, effectiveness, or intended uses of the Juvenon product. The Juvenon label should be consulted for intended uses and appropriate directions for use of the product.

By Benjamin V. Treadwell, Ph.D.

It is not uncommon for medical science to discover additional benefits of a common nutrient initially thought to serve limited specific functions in our tissues. One interesting example is the amino acid, cysteine, which is one of the twenty common amino acids comprising the proteins of our body. Today’s article will describe exciting discoveries about this common amino acid that, when taken in significant amounts, may help protect cells from age-associated degeneration of specific cellular structures.

Cysteine: A Potent Antioxidant

The amino acid Cysteine, in addition to being a critical component of proteins, has extra duties to perform in the cell, including protecting the cell from the damaging effects of the ubiquitous free radicals. In other words, it functions as a potent antioxidant. Interestingly, Cysteine functions as a free-radical neutralizer in two ways: by binding to and neutralizing the radical, and by promoting the synthesis of an endogenous antioxidant, glutathione. This latter antioxidant is involved in numerous enzymatic reactions necessary for sustaining life and protecting the cell from toxins, either those produced by our cells or carcinogens in our environment.

It turns out that a modified version of the amino acid Cysteine, N-acetyl-L-cysteine or NAC, is a more stable form of cysteine and can be converted to the latter in the cell. NAC is available in dietary supplement form.

NAC or glutathione?

For persons interested in protection from toxic compounds, it is more advantageous to take NAC than glutathione, for two reasons. First, NAC is transported into the cell's interior much more effectively than glutathione. Perhaps more importantly, NAC will stimulate the synthesis of glutathione if the cell is deficient in the latter antioxidant. This is important, since too much glutathione is also not healthy. When the cell utilizes cysteine to synthesize glutathione on demand, it can make just the right amount.

NAC protects cellular components from degenerative events associated with toxic compounds.

NAC is currently widely used as an agent to treat patients who have taken toxic doses of acetaminophen, the key ingredient in Tylenol®. (A toxic dose might be as little as 2 or 3 times the recommended dose.) Acetaminophen is converted in the liver to an oxidant that, if present in excessive quantities, destroys liver tissue. This condition can lead to severe liver damage and death if not treated. Treating the patient with NAC is effective in preventing tissue damage if the patient is immediately treated. Apparently, the antioxidant NAC either directly interacts with the toxic acetaminophen-derived compound, and/or promotes the synthesis of glutathione. Both effects will result in neutralization and elimination of the toxin.

		Another Rediscovery Niacin, or vitamin B3, is another rediscovery. In the early 1950's, it was determined that this common vitamin, when taken in large doses, had a significant effect on improving one's lipid profile (lipids are fatty substances such as cholesterol, and triglycerides). Unfortunately, the use of niacin as a prescribed remedy for lowering cholesterol never took off. Prescription of this lipid-lowering vitamin by medical doctors was almost non-existent until about five years ago, following publication of the results of a seminal study on cholesterol-lowering drugs. The study clearly demonstrated that a combination of two compounds, niacin and statins, was very effective at reducing bad cholesterol (LDL) and elevating good cholesterol (HDL), as well as lowering triglycerides. To the surprise of many, niacin proved to have a dramatic positive effect on the lipid profile when combined with the statin-class of cholesterol-lowering drugs. The impact of this study was so great that physicians now often prescribe niacin in combination with statins drugs for patients with poor lipid profiles.

A number of studies with animals indicate that alcohol-associated damage to the liver and brain can also be attenuated by pretreatment with NAC. Alcohol in excess is itself an oxidant. Once consumed, it is converted to even more potent toxic compounds that are destructive to tissue. The destruction appears to result from an ethanol-induced depletion of the cellular antioxidant, glutathione, the major cellular protector from toxic substances. In animal studies, NAC has been demonstrated to help restore the glutathione content to normal cellular levels, as well as directly acting on and neutralizing the alcohol-derived oxidants. In rats, pretreatment with NAC before excessive alcohol consumption has been shown to help prevent damage to tissues including those of the liver and nervous system. Whether this same effect will be verified in humans has not yet been determined.

NAC has been demonstrated to improve circulation in heart and peripheral vessels.

Studies on humans with coronary artery disease have shown a significant increase in vasodilation (increased blood flow) after treatment with NAC. It is known that patients with diseased coronary arteries have an increased presence of oxidants that result in a depletion of glutathione. The endothelial cells, which line the arterial walls, are negatively affected by an imbalance of the oxidant/antioxidant ratio in favor of the oxidant. When this happens, the cells release substances that cause vasoconstriction (decreased blood flow). Left unattended, the high oxidant environment causes inflammation and severe artery disease. Treatment with NAC is believed to improve this condition by restoring balance to the oxidant/antioxidant ratio.

Numerous additional studies support a health-promoting role for the physiological antioxidant NAC. These include protecting our genetic code, especially the mitochondrial genetic code, as well as the delicate lipid constituents of cellular membranes. In addition to its multiple positive health effects, another factor makes this antioxidant even more attractive. Numerous studies, in humans as well as animals, demonstrate its safety as well as the virtual absence of significant side effects.

Why take NAC if you already take other antioxidants?

Antioxidants differ from one another in physical structure as well in their mode of interaction with cellular components. Some are more readily taken up by cells, and they appear to have very specific roles in the highly complex mechanisms of the cell. Furthermore, antioxidants perform additional roles in the cell besides simply acting as an antioxidant, and these roles too are specific to the species of antioxidant. In other words, it takes more than one antioxidant species to provide the global protection the body requires for maximum health.