Glycine - more than just a sweetener

A common struggle, that is a regular topic of conversation amongst parents is sleep, mostly in the younger years, and getting to sleep in particular. Apart from homoepathic remedies, there are few safe and effective options to help sleep onset in children.

The amino acid, glycine is naturally sweet but unlike other natural sweeteners, Glycine has therapeutic benefits. One of these is aiding sleep initiation. Glycine plays an essential role as an inhibitory neurotransmitter via glycine receptors in the peripheral and central nervous systems. It has shown an ability to promote objective and subjective improvements in sleep quality and leads to natural sleep patterns1.

The hypothermic or “cooling” properties of Glycine provide a novel mechanism upon which it regulates sleep-wake behaviour. Core body temperature has a circadian oscillation and drops at the onset of sleep, continues to decrease during sleep and gradually rises as a person wakes2.

Pharmacological findings showed that glycine primarily acts on N-Methyl-D-aspartic acid receptors (NMDAR) in the suprachiasmatic nucleus (SCN) and decreases the body’s core temperature via vasodilation. Thus, the heat dissipation induced by Glycine ingestion leads to an improvement in sleep quality.

Another novel use for Glycine is in improving salicylate metabolism, via glycine conjugation. This is particularly good news for children with salicylate allergies. One study investigated aspirin metabolism in 45 patients who had self-administered an overdose of aspirin. There were four groups, given the following: oral fluids only, Glycine, N-glycylglycine and intravenous sodium bicarbonate. The major metabolite of aspirin is salicyluric acid and salicylic acid.

Plasma Glycine was consistently lower in patients with aspirin overdose than in healthy volunteers, suggesting the glycine was used for the conjugation of salicylate3. Orally administered Glycine and N-glycylglycine increased plasma glycine levels. The rate of excretion of salicyluric acid was higher in patients who received Glycine than in the control group3. The data suggest that supplemental Glycine increases the rate of formation of salicyluric acid in salicylate overdose3.


  1. Yamadera W, Inagawa K, Chiba S, Bannai M, Takahashi M, Nakayama K. Glycine ingestion improves subjective sleep quality in human volunteers, correlating with polysomnographic changes. Sleep Biol Rhythms. 2007;5(2):126-131. doi:10.1111/j.1479-8425.2007.00262.x.
  2. Bannai M, Kawai N, Ono K, Nakahara K, Murakami N. The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers. Front Neurol. 2012;APR(April):1-8. doi:10.3389/fneur.2012.00061.
  3. Patel, D, Ogunbona, A, Notarianni, L, Bennett, P. Depletion of Plasma Glycine and Effect of Glycine by Mouth on Salicylate Metabolism During Aspirin Overdose. Human and Experimental Toxicology. 1990; 9 (6): 389-395.