What is Glycine And What Does It Do In The Body?
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When people think about collagen, they often think about healthy skin, stronger hair, or joint support.
But one of collagen's most interesting qualities has nothing to do with collagen itself.
It has to do with glycine.
Collagen is one of the richest dietary sources of glycine—an amino acid your body uses every single day. In fact, glycine makes up roughly one-third of collagen's amino acid profile, making collagen an easy way to add more of this important building block to your diet.1,2
While glycine is considered a non-essential amino acid because your body can produce it on its own, some researchers suggest our daily needs may exceed the amount we naturally make—especially during periods of growth, aging, exercise, injury, or recovery.3
So where does glycine go once your body has it?
1. Building Your Body's Own Collagen
Glycine is a major structural component of collagen itself. Along with proline and hydroxyproline, it helps form the strong triple-helix structure that gives collagen its strength and flexibility. Your body continuously uses these amino acids as it builds and repairs connective tissues throughout life.1,2
2. Supporting Glutathione Production
Glycine is one of three amino acids required to produce glutathione—often called the body's "master antioxidant." Glutathione helps protect cells from oxidative stress and supports the body's natural antioxidant defenses.4,5
3. Producing Bile Acids
Your liver combines glycine with bile acids before releasing them into the digestive tract. This process helps bile emulsify fats, making dietary fat easier to digest and absorb.5,6
4. Making Creatine
Many people associate creatine with athletes, but your body naturally produces creatine every day. Glycine is one of the amino acids required for this process. Creatine helps store and recycle energy, particularly in muscles and the brain.5,7
More Than Just Protein
Collagen isn’t a complete protein—it doesn’t contain all nine essential amino acids in the amounts needed to fully support muscle protein synthesis. It works best alongside other protein-rich foods as part of a balanced diet.
What collagen does provide is something unique: a concentrated source of glycine, proline, and hydroxyproline—amino acids that are less abundant in many other protein-rich foods. Rather than replacing complete proteins like eggs, Greek yogurt, fish, meat, or legumes, collagen works beautifully alongside them as part of a balanced diet.
That’s exactly why you’ll often find me adding collagen to meals that already contain complete proteins—stirred into Greek yogurt, mixed into smoothies made with milk or whey, or whisked into homemade tzatziki served over a Greek omelet with eggs and feta. It’s a simple way to enjoy the unique amino acids collagen provides while still getting all nine essential amino acids from the rest of the meal.
References
1. Berg JM, Tymoczko JL, Gatto GJ, Stryer L. Biochemistry. 9th ed. W.H. Freeman.
2. Alberts B, et al. Molecular Biology of the Cell. 7th ed. Garland Science.
3. Meléndez-Hevia E, de Paz-Lugo P, Cornish-Bowden A, Cárdenas ML. The demand for glycine is higher than can be met by de novo synthesis in humans. Journal of Biosciences. 2009;34(6):853-872.
4. Wu G. Functional amino acids in nutrition and health. Amino Acids. 2013;45(3):407-411.
5. Rodwell VW, et al. Harper's Illustrated Biochemistry. 31st ed. McGraw-Hill Education.
6. Hall JE. Guyton and Hall Textbook of Medical Physiology. 14th ed. Elsevier.
7. Brosnan JT, Brosnan ME. Creatine: endogenous metabolite, dietary, and therapeutic supplement. Annual Review of Nutrition. 2007;27:241-261.
This article is intended for educational purposes only and should not be considered medical advice. Collagen supplements are not intended to diagnose, treat, cure, or prevent any disease.