Anyone who looks into sleep comes across glycine sooner or later. Before we get to effects, a sober look is worthwhile: what is it, actually?
The simplest amino acid there is
Glycine is the smallest of the twenty protein-building amino acids — so small that it fits in places where no other would have room. That is exactly why it sits where things get tight: in the triple helix of collagen, where every third position is occupied by glycine. Without that tiny size, the structure could not be folded at all.
Collagen makes up around a third of all the protein in the human body. That makes glycine one of the most significant amino acids by quantity — in skin, tendons, ligaments, cartilage and bone.
What the body does with it
Glycine is not a single-purpose substance. It turns up at several points in the metabolism:
- Building block for collagen — that is, for connective tissue, skin and joint structures.
- Precursor of glutathione, one of the body's most important antioxidants. Glutathione consists of three amino acids, one of which is glycine.
- Involved in the formation of creatine, which plays a role in providing energy in muscle and nerve cells.
- Messenger in the nervous system — in the spinal cord and brainstem, glycine acts as an inhibitory neurotransmitter, similar to GABA. It dampens rather than stimulates.
The last point was the first assumption about why glycine might have something to do with sleep. Animal experiments now point to a different route: if this inhibitory glycine receptor is blocked specifically, nothing about the effect changes — the trail leads instead to receptors in the brain region that controls the body clock. What the studies give us — and who carried them out — we have written up in a separate article.
Where glycine comes from
The body can make glycine itself, above all from serine. That is why it counts as non-essential — you do not depend on eating it.
It is not quite that simple, though. Its own production is on the order of a few grams a day, while the requirement for collagen renewal alone is estimated to be higher. Specialists therefore sometimes speak of a conditionally essential amino acid: usually it is enough, under particular strain possibly not.
Through food, glycine comes above all from the parts of the animal that rarely end up on the plate today:
- Bone broth and gelatine — by far the richest sources
- Skin, cartilage and tendons — that is, what used to be cooked along with everything else
- Meat and fish — considerably less, but regularly
- Pulses and seeds — plant sources in smaller amounts
Anyone who eats muscle meat exclusively takes in noticeably less glycine than someone who uses the whole range. That is not a warning about deficiency, but an observation about changed eating habits.
What glycine tastes like
A small aside that surprises many people: glycine tastes slightly sweet. The name comes from the Greek glykys, meaning sweet. That is one of the reasons it is used in food technology.
And where that leaves us
Glycine is not an exotic active ingredient but a basic building block that is constantly needed and used in every body. That is what makes it interesting — because this very central role in the body shows how versatilely glycine is used. Its involvement in numerous natural processes makes it an intriguing component for a holistic view.
