Glycine
The most-underrated amino acid — essential for collagen, glutathione, and deep sleep
Definition
Glycine is the smallest and simplest amino acid, considered 'conditionally essential' in humans: the body synthesises it, but needs exceed endogenous production especially with age, in athletes, and in diets low in collagen/gelatin. It is essential for three critical functions: collagen synthesis (one-third of collagen is glycine), glutathione synthesis (rate-limiting cofactor of the master antioxidant), and inhibitory neurotransmission in the brain (effects on deep sleep and body temperature).
Detailed explanation
Documented applications in clinical and biohacking practice:
Sleep: 3 g of glycine before bedtime reduces sleep latency, increases N3 (deep) sleep phase, and the sense of rest upon waking (studies by Yamadera 2007 and Inagawa 2006). Glutathione synthesis: glycine + N-acetyl-cysteine (NAC) in a formulation called GlyNAC has shown in Baylor clinical trials (Sekhar 2021-2024) significant reduction in oxidative stress, mitochondrial improvement, grip strength, and walking speed in older adults. Collagen and joints: glycine supplementation (5-15 g/day) or hydrolysed collagen (10-20 g/day rich in glycine) improves synthesis of collagen types I and II. Metabolic health: low plasma glycine levels predict incidence of type 2 diabetes and metabolic syndrome (robust independent association).
Dosing: 3-5 g/day dissolved in water (mildly sweet, pleasant taste). For GlyNAC protocols: 100 mg/kg glycine + 100 mg/kg NAC. No significant side effects at nutritional doses. Relative contraindication: clozapine (glycine may reduce its efficacy).
Scientific sources
- PubMed — Glycine ingestion improves subjective sleep quality (Yamadera)
- PubMed — GlyNAC supplementation in older adults improves glutathione and aging hallmarks (Sekhar)
- PubMed — Glycine in metabolic diseases: a potential therapeutic target
- PubMed — The role of glycine in regulating glutathione synthesis
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