Is NAC Safe (Without Glycine)? Maybe

by Nils Osmar. September 10, 2022. Medical Disclaimer
NAC (N. Acetyl Chysteine) is a form of cysteine that is often taken as a nutritional supplement.
When it’s not being used as a supplement, NAC is sometimes used medically to improve fertility, and treat respiratory diseases. It has also been found to support brain health.
NAC for life extension?
- When taken along with glycine, NAC has been shown to extend lifespan in mice by 24%. See study: GlyNAC (Glycine and N-Acetylcysteine) Supplementation in Mice Increases Length of Life by Correcting Glutathione Deficiency, But is NAC safe to take by itself?
- Some studies suggest that supplementing with NAC (alone) lengthens lifespan. When give to C. Eleganz, the worms lived significantly longer. See study: Lifespan extension and increased resistance to environmental stressors by N-Acetyl-L-Cysteine.
From a 2015 study:
Dietary N-acetyl-L-cysteine supplementation significantly increased resistance to oxidative stress, heat stress, and UV irradiation in C. elegans.
In addition, N-acetyl-L-cysteine supplementation significantly extended both the mean and maximum lifespan of C. elegans. The mean lifespan was extended by up to 30.5% with 5 mM N-acetyl-L-cysteine treatment, and the maximum lifespan was increased by 8 days.
N-acetyl-L-cysteine supplementation also increased the total number of progeny produced and extended the gravid period of C. elegans.
A U-shaped curve?
- However, other studies have shown that large amounts of NAC are associated with a shorter lifespan, at least in nemadotes. See study: Antioxidants reveal an inverted U‐shaped dose‐response relationship.
- Lifespan was also extended when it was given in a liposomal form. See study: A method for oral administration of hydrophilic substances to Caenorhabditis elegans: Effects of oral supplementation with antioxidants on the nematode lifespan.
- In sum, the studies are uneven. Some show life extension, in worms and in mammals. Others show that it can either extend or shorten lifespan, at least in worms, depending on the dose given.
Adding glycine
- Other evidence suggests that NAC can have a potent life-extending effect in mammals if it’s accompanied by glycine. See study.
- I take glycine along with NAC because when they’re take in equal amounts, they have been shown to combine in the body to synthesize glutathione, a powerful life-extending molecule.
- I used to take NAC alone at night because it clears up my breathing. But I may actually have been shortening my life.
- I plan to keep taking them in combination, but I’ve stopped taking NAC alone.
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