What Is Glycine? Foods, Benefits, and Why It's Important for Collagen

Around one-third of the amino acids that build up collagen are glycine, making it the most abundant amino acid in collagen.

But what exactly is glycine, and why is it found in such high amounts in collagen-rich foods?

In this article, we'll answer those questions and explore food sources of glycine, its relationship to collagen, and the differences between glycine and collagen supplements.

What Is Glycine?

Glycine is a non-essential amino acid, meaning that the body can produce it itself, although not always in high amounts. Like other amino acids, glycine is used to build proteins throughout the body.

What Does Glycine Do in the Body?

Glycine is involved in a variety of biological processes in the body. Some of its best-known roles include:

Collagen Formation

Glycine is an essential building block for collagen, the structural protein found in skin, bones, joints and connective tissue.

Protein Synthesis

Like all amino acids, glycine is used to build proteins throughout the body that are involved in everything from muscle tissue and enzymes to hormones and immune function.

Neurotransmission

In the brain and spinal cord, glycine acts as a neurotransmitter and helps nerve cells communicate. It also functions as a co-agonist at NMDA receptors, which are involved in memory and learning.

Glutathione Production

Glycine is one of the three amino acids needed to produce glutathione, which is one of the body's main antioxidants.

Why Is Glycine Important For Collagen?

Glycine is the most predominant amino acid in collagen. Along with proline and hydroxyproline, glycine helps form the structure of collagen, which has a triple-helix structure. Glycine can be found at every third position in the triple-helix. Its small size allows the three collagen chains to sit tightly together, giving collagen its strength and stability. 

The main amino acids in collagen include:

• Glycine (~33%)

• Proline

• Hydroxyproline

• Other amino acids

Foods High in Glycine

Glycine is found in a variety of foods, but the richest sources are collagen-rich animal foods.

Foods naturally high in glycine include:

• Bone broth and bones

• Collagen peptides

• Gelatin

• Pork skin

• Chicken skin

• Beef skin

• Tendons and other connective tissues
  
  

Other foods that contain some glycine include:

• Beef

• Chicken

• Fish

• Eggs

• Dairy products

Because glycine is the most significant amino acid in collagen, foods that are rich in collagen generally contain more glycine than muscle meats alone. Except for the foods mentioned above, plant-based foods also contain some glycine.

In the table below, you’ll find an overview of foods that contain glycine, and their collagen content. 

Collagen vs Glycine Supplements

Both collagen and glycine supplements have increased in popularity, and they’re often compared to one another. But should you use both or is one of them enough?

The main difference between them is that glycine is a single amino acid, whereas collagen (usually in the form of collagen peptides in supplements) contains all of the amino acids that are naturally present in collagen, including glycine, proline, and hydroxyproline. 

Because collagen consists of around one-third glycine, collagen supplements provide glycine alongside other amino acids naturally found in collagen. For example, 5 grams of collagen provides roughly 1.5–1.7 grams of glycine, while 5 grams of glycine provides 5 grams of glycine.

Which one to choose depends on your goal. If you specifically want to increase your glycine intake, a glycine supplement provides glycine in its pure form. Collagen peptides, on the other hand, provide glycine alongside other amino acids naturally found in collagen.

Can You Get Enough Glycine From Food?

Collagen-rich animal foods are among the richest dietary sources of glycine, although glycine can be found in a variety of foods. Lean cuts of meat contain some glycine, while collagen-rich parts of the animal typically contain much higher amounts.

Traditionally, many cultures consumed animals nose-to-tail, including skin, connective tissue, tendons, and broths made from slow-simmered bones. These foods contain more collagen and glycine than muscle meat alone.

Today, many people mostly eat lean muscle meats and don’t consume as many collagen-rich foods. For those looking to increase their glycine intake, foods such as bone broth, gelatin, collagen peptides, and collagen-rich cuts of meat are among the best sources.

Conclusion

Glycine is an amino acid naturally found in foods such as bone broth, animal skin, gelatin, and collagen peptides. It's the primary amino acid in collagen, and while the body can produce glycine on its own, it can also be obtained through food. Because glycine makes up around one-third of collagen's amino acid content, collagen-rich foods are among the richest dietary sources of this amino acid.