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Glutathione is an antioxidant compound produced by the body’s cells. It helps prevent damage from oxidative stress caused by the production of reactive oxygen species, a key contributor to the aging process. Glutathione levels decrease with aging. Findings from a new study suggest that supplemental glycine and cysteine restore glutathione levels and correct several markers of aging.
Glycine and cysteine (commonly provided as N-acetylcysteine, or NAC) are amino acids. They play critical roles in the body’s synthesis of glutathione. Glycine and cysteine levels are typically lower in older adults and people with metabolic disease.
The authors of the study conducted a 36-week trial of glycine and cysteine (GlyNAC) supplementation in 16 healthy old (average age, 74 years) and young adults (average age, 24 years). The authors drew blood from the participants and assessed their metabolic, physical, and cognitive health at baseline and at 12, 24, and 36 weeks after the start of the intervention. Assessments included measures of mitochondrial fuel oxidation, oxidative stress, inflammation, glucose metabolism, body composition, and strength tests, among others. The old adults took a GlyNAC supplement (dose varied according to the participants' bodyweight) every day for 24 weeks; the young adults did not take a GlyNAC supplement.
Twenty-four weeks of supplemental GlyNAC restored red blood cell levels of glutathione, reduced oxidative stress, and improved mitochondrial function. Markers of inflammation, endothelial dysfunction, glucose metabolism, and genomic damage decreased. Measures of cognition, strength, and body composition improved. Discontinuation of supplemental GlyNAC negated these improvements.
These findings suggest that supplemental GlyNAC provides a viable means to improve several measures of metabolic, physical, and cognitive health in older adults. This was a very small study, however, and lacked a blinded placebo group. Further study is warranted.
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