Clinical Trials

Baylor College Scientists Reverse Signs of Aging with Antioxidant Cocktail in Older Adults

Clinical trial results show that glycine and N-acetylcysteine (GlyNAC) improves cognition, boosts physical performance, and mitigates insulin resistance in older adults.

By Dylan G. Arrazati

Key Points: 

  • Supplementing older adults with GlyNAC restores cognition, boosts physical function, and mitigates insulin resistance — a condition that can lead to diabetes. 
  • GlyNAC raises natural antioxidant defenses to reduce inflammation, mitochondrial dysfunction, and oxidative stress — damage caused to cells by excessive reactive oxygen species.   
  • The beneficial effects of GlyNAC treatment disappear 12 weeks after stopping treatment, indicating that continual treatment is needed to sustain the accrued benefits. 

Cognitive and physical decline are crippling hallmarks of aging that compromise our ability to live independently, ultimately leading to the need for medical treatment. In attempts to slow these features of aging, our bodies harness the power of antioxidants. However, vital antioxidants like glutathione (GSH), whose deficiency is associated with aging, decrease with age and increase our susceptibility to cellular damage. Thus, finding ways to replenish these vital molecules upon aging is extremely important. 

Researchers from Baylor College of Medicine published a new study in the journal Clinical and Translational Medicine detailing a pilot clinical trial with older adults (70-80 years) given GlyNAC, precursors to our bodies most abundant antioxidant GSH. They showed that GlyNAC successfully improves cognition and boosts physical performance. What’s more, GlyNAC reduced oxidative stress, inflammation, mitochondrial dysfunction, and insulin resistance, all of which accelerate cognitive and physical impairment upon aging. Notably, the accrued benefits of GlyNAC supplementation disappeared 12 weeks after stopping treatment, indicating that continual treatment is needed to sustain GlyNAC’s benefits. 

GlyNac Boosts Cognitive Function in Older Adults  

To examine the clinical effects of GlyNAC supplementation on cognitive function, Kumar and colleagues supplemented older adults with capsules containing glycine (1.33 mmol/kg/day) and N-acetylcysteine (0.81 mmol/kg/day) once a week for 24 weeks. They then conducted an array of tests commonly used to evaluate cognitive function. The findings showed that cognition scores significantly improved after 24 weeks of GlyNAC supplementation, demonstrating GlyNAC’s neuroprotective effects. 

It was also found that GlyNAC supplementation reduced insulin resistance, which the authors suggest could be a driving factor in boosting cognition. Our brains need glucose to function, and increased insulin resistance hinders glucose entry into the brain, so reducing insulin resistance could stimulate brain glucose entry and improve cognition. 

Additionally, GlyNAC drastically reduced inflammation. Inflammation contributes to brain tissue damage and plays a vital role in the development of neurodegenerative diseases like Alzheimer’s and Parkinson’s disease, so GlyNAC could also restore cognitive function by reducing inflammation.

GlyNAC improves cognition
(Kumar et al., 2022 | Clin. Transl. Med.) GlyNAC Improves Cognitive Performance in Older Adults. According to cognitive test scores, young adults (YA) outperform older adults (OA). However, 24-weeks of GlyNAC supplementation improves these scores in OA. 

GlyNAC Improves Physical Performance in Older Adults

The Baylor researchers proceeded to evaluate GlyNAC’s effects on muscle strength and exercise capacity in older adults, measured by grip strength and a six minute rapid walk test. They showed that GlyNAC supplementation improved scores across all physical tests. Supplemented older adults  even performed as well as young adults on the six minute rapid walk test, indicating a reversal of this marker of aging. 

Like our brain, our muscles require sufficient levels of energy to function, which requires our cellular powerhouses (mitochondria) to be healthy. Mitochondria become less healthy and dysfunctional as we age. However, Kumar and colleagues showed that GlyNAC reduced this mitochondrial dysfunction, which could explain the observed improvements in physical performance. 

When our mitochondria become dysfunctional, they produce more reactive oxygen species (ROS). ROS are normally neutralized by antioxidants like GSH, but excessive unneutralized ROS cause damage to cellular components (oxidative stress), including mitochondria. Kumar and colleagues showed that GlyNAC raised the levels of the antioxidant GSH by 200% in older adults, which could explain the reduction in oxidative stress. 

Oxidative stress contributes to nearly all age-related diseases by interfering with the machinery of our cells. This includes the machinery involved in insulin signaling, which can lead to insulin resistance. What’s more, elevated ROS levels are almost always associated with increased inflammation and mitochondrial dysfunction. Thus, hypothetically, by reducing oxidative stress, inflammation, and mitochondrial dysfunction, GSH restoration could mitigate brain, muscle, and cellular deterioration, resulting in improved cognition, physical performance, and metabolism (insulin signaling). However, a larger randomized clinical trial, along with more animal studies are needed to confirm this hypothesis. 

GlyNAC increases physical fitness in seniors
(Kumar et al., 2022 | Clin. Transl. Med.) GlyNAC Boosts Physical Performance in Older Adults. According to physical test scores, young adults (YA) outperform older adults (OA). However, 24-weeks of GlyNAC supplementation improves these scores in OA. 

Should Older Adults Start Taking GlyNac? 

The study’s findings are quite compelling given that medical interventions for aging and age-related diseases are severely lacking. The Baylor researchers demonstrate that GlycNAC supplementation could potentially promote healthy aging by mitigating critical hallmarks of aging: mitochondrial dysfunction, inflammation, and oxidative stress. Furthermore, GlyNAC supplementation appears to be well tolerated with no apparent adverse effects, and since GlyNAC supplements are widely available, it may be worth trying. Interestingly, GlyNAC supplementation has also been shown to increase the lifespan of mice, further highlighting its potential to boost longevity. Overall, GlyNAC supplementation warrants further research to fully elucidate its protective effects against aging. 

Model & Dosage

Old Adults: (70-80 years old) ; Young Adults: (20-30 years old)

GlyNAC: capsules containing glycine (1.33 mmol/kg/day) and N-acetylcysteine (0.81 mmol/kg/day) once a week for 24 weeks


Kumar P, Liu C, Hsu JW, et al. Glycine and N-acetylcysteine (GlyNAC) supplementation in older adults improves glutathione deficiency, oxidative stress, mitochondrial dysfunction, inflammation, insulin resistance, endothelial dysfunction, genotoxicity, muscle strength, and cognition: Results of a pilot clinical trial. Clin Transl Med. 2021;11:e372.

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