Key takeaways
- Glycine is classified as non-essential, but research suggests most people don't get enough from diet alone.
- It plays a role in gut lining integrity, sleep quality, collagen production, and inflammation regulation.
- Bone broth made from slow-simmered bones is one of the richest natural dietary sources of glycine.
- The evidence is promising but still developing — no medical claims are made here.
What is glycine?
Glycine is the simplest amino acid in the human body. It's classified as "non-essential," meaning the body can produce it on its own — but research increasingly suggests that the amount synthesized may not always meet demand.
It's found in high concentrations in collagen-rich foods: skin, cartilage, tendons, and bones. For most of human history, these were a regular part of the diet. Today, they largely aren't — and that gap may matter more than we previously thought.
The main benefits of glycine
Sleep quality
A well-designed Japanese study found that 3g of glycine taken before bed improved sleep quality and reduced daytime fatigue. The mechanism appears to involve glycine's role in lowering core body temperature at night — a key signal for the body to enter deep sleep.
Gut lining support
The gut lining is a single layer of cells separating what you eat from your bloodstream. Glycine appears to support the integrity of tight junctions — the connections between gut lining cells — helping maintain this barrier. Animal studies support this; early human research is promising but limited.
Collagen production
Glycine makes up roughly one-third of collagen by weight. Without adequate glycine, the body's ability to produce and maintain collagen — relevant for joints, skin, tendons, and cartilage — is compromised.
Inflammation regulation
Glycine has been shown to inhibit the activation of certain immune cells involved in inflammatory responses, with growing interest in its role in managing chronic low-grade inflammation.
Why bone broth is one of the best sources
Bone broth made from slow-simmered bones and connective tissue is one of the most concentrated natural sources of glycine in the diet. The long cooking process — typically 12 to 18 hours — breaks down collagen into gelatin and free amino acids, including glycine, proline, and hydroxyproline.
Unlike isolated glycine supplements, bone broth delivers these amino acids within a natural food matrix — alongside minerals and other compounds that may work together in ways supplements don't replicate.
The exact glycine content varies depending on the bones used, the simmering time, and the preparation method. This variability is a genuine limitation compared to a supplement with a stated dose — but it comes with the advantage of being a whole food rather than an isolated compound.
What glycine can't claim in Europe
In Europe, health claims on food products are tightly regulated by the EFSA. Claims linking glycine or collagen to specific health outcomes are not authorized on packaging or marketing unless backed by approved dossiers. The honest position: the science is genuinely interesting, the mechanisms are plausible, and the evidence base is growing — but it isn't yet at the level that justifies medical claims.
Who should think about glycine intake?
If your diet is rich in muscle meat but low in collagen-containing foods — which describes most modern Western diets — you may be getting less glycine than your body can optimally use.
Adding bone broth as part of a varied diet is a low-risk, historically grounded way to increase glycine intake naturally. It won't replace a balanced diet, but as a daily ritual with a genuinely favorable nutritional profile, it has a strong case.
Summary
Glycine plays a meaningful role in sleep, gut lining integrity, collagen synthesis, and inflammation — but the research is still developing. Bone broth is one of the richest natural dietary sources of glycine, particularly when made from bones simmered for an extended period. The evidence doesn't support dramatic health claims, but it does support bone broth as a thoughtful, natural addition to a daily routine.
“Bone broth won't fix everything — but as a daily source of glycine, it's hard to beat.”
Frequently asked questions
- What are the main benefits of glycine?
- Glycine supports sleep quality, gut lining integrity, collagen production, and inflammation regulation. Research is still developing, but the evidence base is growing.
- Is bone broth a good source of glycine?
- Yes — bone broth made from slow-simmered bones is one of the richest natural dietary sources of glycine, alongside proline and hydroxyproline.
- How much glycine does bone broth contain?
- It varies depending on the bones used and simmering time. A well-made bone broth simmered for 12–18 hours will contain meaningful amounts of glycine, though exact levels differ by preparation.
- Can I get enough glycine from diet alone?
- The body produces glycine, but research suggests most people consuming a modern Western diet — rich in muscle meat but low in collagen-containing foods — may not produce enough to meet optimal needs.
