Glycine: the sleep amino acid, and the founder of tissues and cells

Glycine holds a singular place in human biochemistry: on its own it accounts for nearly twelve percent of the body's amino acids, a proportion no other reaches. Its recent fame was built around sleep, which leaves most of its physiological activity in the shadows. The real question is its actual role in the body, and its presence at 750 mg in a daily micronutritional formula. The answer spans four documented domains: the construction of connective tissues, glutathione synthesis, one-carbon metabolism and the integrity of the intestinal lining. Sleep comes after, as one facet among others.

What is glycine?

Glycine is the simplest of amino acids, and yet one of the most versatile. Its structure reduces to an amine group, a carboxyl group and a hydrogen atom as its side chain. This extreme simplicity founds its singularity: its small size gives it access to molecular positions where no other amino acid can lodge.

Long classed as non-essential because the body knows how to make it, it is now recognised as conditionally essential. Internal synthesis, mainly from serine, rarely covers the full need. Meléndez-Hevia et al. (2009) established the calculation: human biosynthetic capacity sits far below the amounts required for collagen synthesis alone, with an estimated gap of several grams per day. A dietary or supplemental intake therefore often becomes necessary to support its many functions.

The structural pillar of tissues

Glycine's first role concerns the construction and maintenance of tissues. It is the major constituent of collagen, the body's most abundant protein, where it occupies one position in three along the chain and stabilises the famous triple helix. The repeated sequence glycine, proline, hydroxyproline forms the basic motif of this coil; no other molecule can replace it there, because only its small size fits at the geometric centre of the helix, where three chains draw closest together.

Skin, tendons, cartilage, bone, vessel walls and the supporting matrix depend on its availability. The work of de Paz-Lugo et al. (2018) on articular chondrocytes shows that a sufficient glycine concentration directly increases collagen synthesis, and that a deficit slows cartilage repair. This structural function also covers wound healing and the renewal of all connective tissues.

Your collagen is made by you

This dependence opens a perspective few consumers know. Collagen ingested as peptides is fully digested into amino acids and dipeptides before absorption, and the body then rebuilds its own chains from these bricks. Endogenous synthesis remains the final mechanism, and it demands two simultaneous conditions: glycine availability, and the presence of vitamin C.

Vitamin C acts as cofactor of the prolyl- and lysyl-hydroxylase enzymes, which hydroxylate the proline and lysine residues of procollagen; this hydroxylation conditions the thermal stability of the triple helix. Murad et al. (1981) documented the direct stimulation of collagen synthesis by ascorbic acid in human fibroblasts. Vitamin C contributes to normal collagen formation for the normal function of skin, bones, cartilage, teeth, gums and blood vessels.

base One combines 750 mg of glycine and 580 mg of vitamin C in the same intake: the substrate and the cofactor, together in the same absorption window.

The glutathione precursor and cell protection

Glycine is one of the three amino acids composing glutathione, with cysteine and glutamic acid. Glutathione is the main antioxidant made by the cell itself, guardian of oxidative balance and pillar of hepatic detoxification. Insufficient glycine availability limits glutathione production, reduces antioxidant defences and weakens cell protection. Sekhar et al. (2011) measured, in elderly subjects, a restoration of glutathione synthesis and red-cell concentration after combined glycine and cysteine intake, with a concomitant fall in oxidative stress markers. Glycine also takes part in the conjugation of foreign substances, a mechanism by which the liver neutralises and eliminates certain toxic compounds.

Cell metabolism and the mitochondrion

At the heart of the cell, glycine feeds one-carbon metabolism, the biochemical crossroads that commands DNA synthesis, gene repair and methylation. The glycine cleavage system transfers a methylene group to tetrahydrofolate, directly linking this amino acid to the folate cycle and to that of vitamin B12. It enters the making of heme, the core of oxygen-carrying haemoglobin; of creatine, the rapid energy reserve of muscle and brain; and of the purine bases of our nucleic acids. Recent research underlines its role in supporting mitochondrial function, the organelle that produces cellular energy.

The intestinal lining, a tissue in its own right

The intestine perfectly illustrates glycine's double role, both a tissue to maintain and a surface to protect. Intestinal wall cells possess a specific transporter, GLYT1, which lets them accumulate glycine and resist oxidative stress; Howard et al. (2010) established this transporter's indispensable character in protecting human intestinal epithelial cells against oxidative damage. This uptake protects colonocytes and supports the integrity of the intestinal barrier. By preserving the tight junctions between cells and the epithelium's mitochondrial function, glycine helps maintain a healthy mucosa and limit intestinal permeability, commonly called leaky gut. The formula extends this logic with 1,500 mg of L-glutamine, the preferential fuel of enterocytes: two amino acids covering two complementary sides of digestive-wall maintenance.

Other notable physiological functions

Glycine also takes part in fat digestion, through the conjugation of bile acids that facilitate lipid absorption, producing glycocholic acid, the majority form of human bile salts. It modulates the immune response by regulating certain cytokines and intracellular calcium balance. Low glycine concentrations are regularly observed in obesity, type 2 diabetes and hepatic steatosis, suggesting a link between its status and global metabolic health (Alves 2019).

Glycine and sleep: what the studies show

Glycine also acts as an inhibitory neurotransmitter in the central nervous system. It binds the glycinergic receptors of the brainstem and spinal cord, and occupies the co-agonist site of NMDA receptors, notably in the suprachiasmatic nucleus. Yamadera et al. (2007) observed, in subjects dissatisfied with their sleep, improved subjective sleep-quality scores after 3 g taken before bed. Kawai et al. (2015) documented the underlying mechanism: peripheral vasodilation followed by a drop in core body temperature, two physiological events that accompany natural sleep onset. Bannai and Kawai (2012) described the central pathway of this thermoregulatory effect. This property, often the only one put forward, is in reality one facet among others: used in the daytime, glycine deploys above all its structural, antioxidant, cellular and intestinal functions.

Why 750 mg in base One

The chosen dose follows a daily baseline logic, distinct from the one-off 3 g doses used in sleep-study protocols. Three reasons found it. Coherence with the cofactors present: vitamin C at 580 mg for collagen hydroxylation, L-glutamine at 1,500 mg for the intestinal mucosa, zinc at 5 mg for epithelial repair, vitamin B6 as P5P at 10 mg for the trans-sulfuration route that supplies the cysteine of glutathione. Galenics: glycine has a naturally sweet taste, without glycaemic load and without synthetic sweeteners, and its 750 mg contribute to the drink's taste profile. Rhythm: structural needs express themselves continuously, in the permanent synthesis of collagen, glutathione and purine bases; a regular daily intake answers this baseline demand, and leaves the door open to a dedicated evening supplement for whoever wants to explore the sleep route.

FAQ

Glycine in the evening?

Sleep studies use about 3 g roughly an hour before bed. The baseline intake in base One follows a different logic: daily support of structural and cellular functions.

Does glycine taste sweet?

Its name comes from the Greek glykys, meaning sweet. It brings a natural mild sweetness, without sugar and without synthetic sweeteners.

What are the benefits of glycine?

The scientific data describe it as the major constituent of collagen, a glutathione precursor, an actor of one-carbon metabolism and a protector of the intestinal epithelium. Sleep studies observe a central thermoregulatory action.

David Giovenco · Micronutrition researcher · President, Académie Internationale Francophone de Médecine Orthomoléculaire et Intégrative · Founder & Formulator, nuho

Sources

Murad 1981 (PNAS) · Yamadera 2007 · Meléndez-Hevia 2009 · Howard 2010 · Sekhar 2011 · Bannai & Kawai 2012 · Wang 2013 · Kawai 2015 · de Paz-Lugo 2018 · Alves 2019 · Metabolism Clin Exp 2025 · Frontiers in Pharmacology 2025.