Aging affects every cell in the body. Glutathione levels fall, oxidative stress rises, mitochondria slow down, and inflammation becomes harder to control. A randomized, double‑blind, placebo‑controlled human trial tested whether restoring glutathione with GlyNAC—a combination of glycine and N‑acetylcysteine (NAC)—could help older adults regain healthier cellular function.

The study was published in The Journals of Gerontology: Series A in 2023 and registered as NCT01870193. It included 24 older adults (61–80 years) and 12 young adults (21–40 years) for comparison.

Why GlyNAC?

Glutathione (GSH) is the body’s master antioxidant. It protects cells, supports mitochondria, and helps maintain healthy inflammation levels. Older adults often become deficient in the two amino acids needed to make glutathione:

• Glycine
• Cysteine (provided here as NAC)

When glutathione falls, oxidative stress rises, and mitochondria struggle to produce energy efficiently. GlyNAC aims to restore glutathione by supplying its missing building blocks.

What the Study Found

1. Glutathione levels normalized

• Older adults began with about 66% lower glutathione than young adults.
• After 16 weeks of GlyNAC, glutathione increased by ~164%.
• Levels became indistinguishable from young adults.
• No improvement occurred in the placebo group.

2. Oxidative stress dropped sharply

• Key oxidative stress markers fell by about 72%.
• Values returned toward youthful ranges.
• No change in placebo.

3. Mitochondrial function improved

• Improved fatty‑acid oxidation.
• Normalized respiratory quotient (RQ).
• Improved expression of mitochondrial regulators (PGC‑1α, Sirtuin‑3, AMPK).

4. Inflammation and endothelial function improved

• Reductions in IL‑6, TNF‑α, and CRP.
• Improved markers of vascular health.

5. Several aging hallmarks shifted toward youthful levels

• Genomic damage markers
• Mitophagy proteins (PINK1, LC3)
• Stem‑cell fatigue markers (PAX7)
• Cellular senescence markers (p16^INK4a)
• Telomere‑protection protein (POT1)

6. Physical function improved

• Faster gait speed
• Improved upper and lower body strength
• Trend toward better 6‑minute walk distance

7. Waist circumference and blood pressure improved

• Waist circumference decreased
• Systolic blood pressure dropped
• No meaningful change in placebo

What This Study Does Not Show

• The study was small (24 older adults).
• It lasted 16 weeks, not years.
• It did not measure disease risk or lifespan.
• Aging‑hallmark markers were exploratory.
• The research team holds a patent on GlyNAC (licensed to Nestlé Health Science).

The findings are promising but represent early‑stage human evidence.

What This May Mean for Older Adults

This trial suggests that restoring glutathione through GlyNAC may help:

• Reduce oxidative stress
• Improve mitochondrial efficiency
• Support healthier inflammation levels
• Improve strength and walking ability
• Shift several cellular aging markers in a youthful direction

Larger and longer studies are still needed before drawing firm conclusions.

Reference

The study is available here: Supplementing Glycine and N-Acetylcysteine (GlyNAC) in Older Adults.