Glycine

About Glycine

The smallest amino acid, non-essential but required in large amounts for collagen — which is roughly one-third glycine — and for glutathione and creatine synthesis. It tastes distinctly sweet.

Glycine has two separate literatures. The sleep one comes from a small set of Japanese trials, several conducted by a company that produces amino acids, reporting that 3 g before bed improved subjective sleep quality and next-day alertness and shortened the time to reach slow-wave sleep, plausibly through a mild drop in core body temperature. The other is the argument that ordinary diets supply less glycine than collagen synthesis demands, making it conditionally essential — an interesting metabolic case with almost no outcome evidence behind it. Both are more modest than the marketing around glycine as a longevity compound suggests.

Sold as

Powder, Capsule, Combined with magnesium as magnesium glycinate

Standardised to

Grams of free glycine — a product without this marker may not resemble what was studied.

Also known as

Glycine, Aminoacetic acid

Regulation: Sold as a dietary supplement and used as a food ingredient with no pre-market efficacy review.

What the research used

The amounts, forms and durations published trials of Glycine actually administered.

When it was taken

Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.

In the food catalogue

The whole-food form, where one exists. The evidence for a concentrated extract rarely transfers to the food, or the other way round — these are cross-links, not equivalents.