A paper published in the Nature Journal, Eye, suggests that N-acetyl-cysteine (NAC) may lower elevated levels of matrix metalloproteinase-9 (MMP-9) activity associated with ocular surface and corneal disease.

Matrix metalloproteinase-9 is a human enzyme encoded by the MMP9 gene.

Excessive amounts are associated with ocular surface disease including dry eye, as well as diabetic retinopathy, retinitis pigmentosa, arthritis, intracerebral hemorrhage, metastasis and collagen degradation.

NAC is the acetylated form of the amino acid L-Cysteine. It has been suggested in a large number of published scientific studies to rapidly metabolize to intracellular glutathione, the mother-of-all-antioxidants found inside every cell in the body, including the eye.

Glutathione is produced in the liver from three amino acids, cysteine, glutamic acid and glycine, with cysteine being the major player.  Very small amounts are found naturally in fruits and vegetables, but absorption rates of both natural and supplemental glutathione seem to be fairly low.

Dietary cysteine is primarily found in egg yolk, which probably puts vegans who don’t take supplemental NAC at risk.

A review published in the American Family Physician suggests that NAC supplementation is linked to prevention of chronic obstructive pulmonary disease, prevention of kidney damage during imaging procedures, and attenuation of illness from the influenza virus, if started before infection, as well as eradication of Helicobacter pylori and hearing loss in patients on renal dialysis.

The long-proven ability of NAC to increase glutathione production is particularly important during flu and cold season:

1. Evidence suggests that glutathione helps the body inhibit viral replication.

2. Adequate glutathione levels help to prevent unwanted mucus buildup in the lungs.

3. Double-masked research suggests that NAC supplementation lowers the risk of chronic bronchitis recurrences.

A recent study looked at NAC glutathione and markers of inflammation and oxidative stress in an early model of diabetic retinopathy. The results show that plasma markers of oxidative stress and inflammation are minimized with NAC treatment.  This suggests that early supplemental therapies can reduce free radical damage in the diabetic eye.

NAC and Alzheimer’s

A study published in an August 2009 peer-reviewed journal on rats treated with aluminum to induce cognitive dysfunction similar to that of Alzheimer’s disease had promising results for those at genetic risk of developing Alzheimer’s disease. The study subjects pre-treated with NAC maintained significantly improved memory retention during tasks, decreased oxidative damage and reduced acetyl-cholinesterase activity, which is the enzyme that breaks down the neurotransmitter acetylcholine that plays a key role in memory, learning and many other brain functions.  The NAC untreated rats did not fare well at

NAC and Tylenol

NAC has been used in hospitals for years to treat liver damage caused by mostly excessive Tylenol (acetaminophen) intake.

Even though Tylenol controls about 35% of the pain killer market in North America; acetaminophen overdose is responsible for more emergency room visits than any other medicine on the OTC market.

Has anyone ever thought of including NAC in Tylenol?

Don’t jump on the obvious too fast! NAC is more efficacious when taken as part of a full-spectrum vitamin/mineral/antioxidant multiple. It chelates heavy metals, including mercury, and it also increases the excretion of zinc, copper and other minerals if excessive amounts are taken over an extended period of time.

Ellen Troyer, MT MA, with Spencer Thornton, MD and the Biosyntrx Staff

PEARL: Again, we come back to the importance of micronutrient synergy and ask this question: as a reasonable safety precaution, doesn’t it make biological sense NAC to be included in, or taken with, AREDs formulations that include excessively high amounts of zinc?

We are also intensely interested in emerging science around the therapeutic use of antioxidants, including NAC, for clinical depression.