GlyNAC Improves Aging Markers in Older Adults - Study

clinical-trial PMID: 33783984

Quick Summary: A recent study found that a supplement called GlyNAC (a combination of glycine and N-acetylcysteine) helped older adults in several ways. It improved their glutathione levels, reduced oxidative stress, and boosted their overall health, including muscle strength and thinking skills.

What The Research Found

This research looked at how GlyNAC affects older adults. The study showed that taking GlyNAC for 24 weeks:

Increased Glutathione: Helped boost levels of glutathione, an important antioxidant.

Reduced Oxidative Stress: Lowered levels of harmful molecules that can damage cells.

Improved Energy Production: Enhanced the function of mitochondria, the "powerhouses" of cells.

Reduced Inflammation: Lowered levels of inflammation in the body.

Improved Blood Vessel Function: Helped blood vessels work better.

Improved Insulin Sensitivity: Made the body better at using insulin.

Improved Cognition: Improved thinking skills and memory.

Increased Muscle Strength: Made muscles stronger.

Improved Walking Speed: Helped people walk faster.

Reduced Body Fat: Lowered body fat and waist size.

However, when people stopped taking GlyNAC, some of these benefits started to fade.

Study Details

Who was studied: 8 older adults.

How long: 36 weeks total: 24 weeks taking GlyNAC, followed by 12 weeks without it.

What they took: GlyNAC, a combination of glycine and N-acetylcysteine (NAC). The specific doses were not provided in the study summary.

What This Means For You

This study suggests that GlyNAC might be helpful for older adults looking to improve their health. It could potentially help with:

Boosting energy levels

Improving brain function

Increasing muscle strength

Reducing the effects of aging

However, it's important to remember that this was a small study. More research is needed to confirm these findings.

Study Limitations

Small Study: Only a small number of people were involved.

No Placebo: Everyone in the study took GlyNAC; there was no group that didn't take it to compare results.

Short Duration: The study only looked at the effects for a limited time.

No Long-Term Data: The study didn't follow people for a long time to see if the benefits lasted.

Key Findings

GlyNAC (glycine + N-acetylcysteine) supplementation for 24 weeks in older adults corrected red blood cell (RBC) glutathione deficiency, reduced oxidative stress, and restored mitochondrial fuel oxidation. It significantly improved inflammation, endothelial dysfunction, insulin resistance, genomic damage, cognition, muscle strength, gait speed, and exercise capacity while reducing body fat and waist circumference. Benefits partially reversed after 12 weeks of withdrawal, indicating sustained supplementation is necessary. The study concluded GlyNAC is well-tolerated and addresses multiple age-related dysfunctions by targeting glutathione deficiency.

Study Design

This 36-week open-label pilot clinical trial included 8 older adults (OAs; mean age not specified in summary) and 8 young adults (YAs) at baseline. After initial assessments, YAs exited the study. OAs underwent GlyNAC supplementation for 24 weeks followed by a 12-week withdrawal period. Primary outcomes measured RBC glutathione, mitochondrial fuel oxidation (MFO), plasma biomarkers (oxidative stress, inflammation, endothelial function, glucose/insulin), physical performance (gait speed, grip strength, 6-minute walk test), cognitive function, genomic damage, and body composition.

Dosage & Administration

The specific doses of glycine and N-acetylcysteine (NAC) in the GlyNAC formulation were not quantified in the provided study summary. Supplementation was administered orally for 24 consecutive weeks, followed by a 12-week cessation period to assess withdrawal effects.

Results & Efficacy

GlyNAC corrected RBC glutathione deficiency (p<0.05, though exact values not detailed in summary) and normalized oxidative stress markers. Mitochondrial fuel oxidation improved significantly (p<0.05), alongside reductions in inflammatory cytokines (e.g., TNF-α, IL-6), insulin resistance (HOMA-IR), and endothelial dysfunction markers (e.g., ICAM-1). Cognitive scores (e.g., MoCA), grip strength, and 6-minute walk distance increased, while body fat and waist circumference decreased. All improvements regressed toward baseline during the 12-week withdrawal phase, confirming treatment dependency. Statistical significance (p<0.05) was reported for primary outcomes, but exact effect sizes and confidence intervals were not provided in the summary.

Limitations

The study had a very small sample size (n=8 OAs), no placebo control, and an open-label design, risking performance and detection bias. Lack of a concurrent OA control group limits causal inference. Young adults served only as baseline comparators and were not followed longitudinally. Short withdrawal duration (12 weeks) and absence of long-term safety data restrict conclusions about sustainability. Mechanistic insights were limited, and results require validation in larger, randomized, double-blind trials.

Clinical Relevance

For older adults, GlyNAC may offer a multi-system intervention targeting glutathione deficiency—a key driver of aging—potentially improving metabolic, cognitive, and physical health. However, benefits appear temporary, necessitating ongoing use. Given the pilot nature and small sample, this does not support broad clinical recommendations yet. Users should prioritize consulting healthcare providers before supplementation, as optimal dosing, long-term safety, and efficacy in diverse populations remain unconfirmed. Larger trials are essential to translate these findings into practice.