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Glycine is a single amino acid, one of the building blocks for protein, as well as a calming neurotransmitter, best known as a calming influence on the NMDA receptors involved in learning and memory (or excitotoxicity, if they are overstimulated). 

In its role as a protein building block, glycine is particularly important for collagen, elastin, creatine, heme formation, bile salts, and glutathione. The roles for these two are critical, and deficiency in glycine can therefore have far-reaching results. And deficiency is more common than you might think. 

Why We’re Low in Glycine

This paper suggests that, with all of its many various jobs in the body, including collagen turnover, heme formation, glutathione levels, and the rest, optimal intake for glycine is around 15 grams per day. Twelve grams of this go toward collagen turnover, and the surplus should be sufficient for the rest. 

However, while glycine isn’t considered an essential amino acid (meaning our bodies are capable of producing it), we only make three grams per day, dairy, and beans, and average dietary intake is around another two or three grams daily. 

That means most of us are still short around 9-10 grams. 

Glycine and Collagen

As mentioned, 12 grams of glycine daily would be needed for optimal collagen turnover.

Collagen is a popular anti-aging and joint supplement, for good reason: it’s not only the most critical structural protein in skin and joints, but it’s also the structural component of blood vessels as well. 

A number of nutrients are necessary for the body to make collagen, but glycine is one of the most abundant amino acids in its structure. If you take collagen (or eat bone broth), you’re already getting glycine as part of it — but this may be insufficient for your overall needs for collagen turnover, let alone for other purposes besides.

Glycine, Glutathione, and Oxidative Stress

Glutathione is the body’s master antioxidant. It’s a tripeptide comprised of the amino acids glycine, glutamine, and cysteine. NAC (the activated version of cysteine) is often the rate-limiting step in glutathione formation, but sometimes that is insufficient to raise levels. Glycine deficiency may be the reason. 

Aside from its use as a building block in glutathione, glycine also helps to decrease oxidative stress by blocking production of superoxide free radicals from oxygen via NADPH. 

Glycine is also required for production of inflammatory proteins like C-reactive protein too—which means that oxidative stress tends to deplete glycine by consuming it in production of CRP. If this means there’s not enough left over to make glutathione, or to block NADPH, then the problem is compounded. 

Glycine and the Brain

In addition to its other jobs, glycine is involved in the production of new neurons. This may be why it’s regulated by Brain-Derived Neurotropic Factor, or BDNF, which is necessary to create new neural pathways.

This is probably why glycine has been shown to aid in memory.

The Upshot

Glycine has many more functions than those highlighted here, including aiding in repair of intestinal mucosa, improving depth and quality of sleep, and more. 

Glycine has a very mild sweet flavor, and can be used as a sweetener in tea or coffee (or hidden in a smoothie). Considering the shortfall for most of us, it’s not a bad idea to add it in. Here’s one I’d suggest.