Glycine + NAC (GlyNAC): oxidative stress, mitochondrial aging, and restoration of cellular resilience
One underestimated, yet fundamental driver of ageing is the gradual decline of the body’s own antioxidant system. As we grow older, the availability of glutathione in particular decreases—the main intracellular antioxidant. Glutathione plays a central role in neutralising reactive oxygen species, protecting mitochondria, and supporting detoxification and repair. A shortage of glutathione contributes directly to several Hallmarks of Aging, including oxidative stress, mitochondrial dysfunction, and inflammation associated with ageing.
Glycine and N-acetylcysteine (NAC) together form a particularly effective combination, often referred to as GlyNAC, because they supply exactly the two limiting building blocks needed for glutathione synthesis. Glutathione consists of three amino acids: glycine, cysteine, and glutamate. With ageing, the availability of glycine and cysteine in particular appears to decline, causing glutathione production to fall short on an ongoing basis. NAC acts as a well-absorbed precursor of cysteine, while glycine completes the synthesis.
The central role of glutathione in redox balance, mitochondrial protection, and cellular survival is described in depth in a mechanistic review in Free Radical Biology & Medicine, which explains how glutathione is essential for preserving mitochondrial function and limiting oxidative damage.3
That a shortage of glutathione truly contributes to ageing is also shown by human studies. In a series of studies led by Kumar et al., it was demonstrated that older adults have significantly lower glutathione levels than younger adults, together with increased oxidative stress, reduced mitochondrial function, and poorer physical performance.
In a randomised, controlled human study published in Clinical and Translational Medicine, older adults received GlyNAC supplementation for 24 weeks. The results were striking: the supplementation restored glutathione levels, lowered oxidative stress, improved mitochondrial energy production, and led to measurable improvements in muscle strength, walking capacity, and overall physical function.²
In addition, the researchers observed improvements in insulin sensitivity, inflammation markers, and markers of fatigue. These findings are especially relevant for longevity, because they show that restoring a fundamental antioxidant system can positively influence multiple mechanisms of ageing at the same time.
Preclinical studies further support this picture. In animal models, restoring glutathione leads to improved mitochondrial biogenesis, lower inflammatory activity, and better cellular resistance to stress. These effects closely match the human data and underline that GlyNAC does not merely address a symptom, but corrects an underlying biological deficiency.
What sets GlyNAC apart from many other supplements is that it does not try to “force” ageing, but helps the body return to a more youthful biochemical balance. By restoring the availability of glutathione, mitochondria are better protected, energy production becomes more efficient, and inflammatory processes are restrained.
Within a longevity strategy, GlyNAC is therefore an exceptionally strong intervention. It supports oxidative balance, mitochondrial health, and functional capacity at the same time—three pillars that determine how healthily we grow older. Glycine and NAC are valuable on their own, but together they form a synergistic building block for those who not only want to live longer, but above all want to keep functioning at a high level for longer.
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