Glycine is the smallest, most abundant and versatile amino acid of them all.
It is found everywhere in the body, as it performs so many important tasks and is involved in so many processes.
It has a broad spectrum of anti-inflammatory (strongly lowers markers of inflammation such as TNF-alpha, IL-6 and TF-kB), cytoprotective (protects cells against damage) and immunomodulatory (boosts immunity) properties. It’s also important in the synthesis of heme (iron and red blood cells), formation and repair of RNA/DNA, maturing satellite cells, helping with the absorption of calcium in the body and increasing muscle protein synthesis by activation of the mammalian target of rapamycin (mtOR) signaling pathway.
Improves alertness and is anti-anxiety
As a non-essential amino acid, glycine has indispensable roles in both excitatory and inhibitory neurotransmission via N-methyl-D-aspartate (NMDA) type glutamate receptors and glycine receptors, respectively. Meaning it can help keep you awake and alert, and also help with calmness and sleep.
For e.g. exogenous glycine (glycine supplementation) promotes sleep by causing peripheral vasodilation through the activation of NMDA receptors in the brain, as well as increases REM sleep and decreases non-REM sleep.
This brain vasodilation (of the micro vesicles) isn’t just useful for sleeping but will enhance brain function during waking hours. It reduces fatigue and sleepiness for sleep deprived/fatigued individuals. Glycine also has a strong anti-anxiety and anti-psychotic effect.
Glycine aids in the convertion of progesterone to allopregnanolone (neurosteroid) by 5-alpha reductase in the brain. Allopregnanolone exerts neurogenetic (growth of new neurons), neuroprotective (protect neurons from damage), antidepressant, anti-anxiety and cognitive alertness effects.
A shortage of glycine in the brain can negatively influence the brain’s neurochemistry, synthesis of collagen, RNA/DNA, porphyrins, and other important metabolites (1).
Glycine enters the folate cycle to produce 5,10-methylenetetrahydrofolate (MTHFR). MTHFR is a gene important in the methylation cycle for converting homocysteine to methionine and also in DNA synthesis. Methionine can then be converted to S-adenosylmethionine (SAM) which is the universal methyl donor.
Once our methylation need for methionine is met, we use vitamin B6 and glycine to convert any additional homocysteine in our diet to glutathione (which is the master antioxidant and detoxifier of the cell as well as a key regulator of protein function) or sulfate or taurine. Glycine is thus a methylation buffer to prevent a buildup of homocysteine. So it can be a very handy tool, essential I would say, for optimal energy, health and well-being.
Improves fat digestion & fat burning
Glycine helps with the digestion of fats as it’s involved in the synthesis of bile salts and bile acid glycocholic acid. Bile acid is an emulsifying agent which breaks down fat into smaller molecules, making the surface area bigger for lipase (the enzyme that digests fat) to bind to and do a proper job digesting fat, so that all the fat molecules can be absorbed and utilized in the body. Glycine also stimulates glucagon release, which increases fat breakdown to increase fatty acids to be burned as energy.
Glycine also helps synthesize carnitine, which then transports fatty acids into the mitochondria to be burned for energy.
It also increases adiponectin which increases insulin sensitivity, reduces inflammation and stimulates beta-oxidation (burning fat as fuel)
Increases the integrity and repair of connective tissue
Glycine is found in high concentrations in the skin, joints and other connective tissue. So supplementing with glycine is very good for joints, skin, hair, intestinal lining and many other organs, as it is involved in collagen formation and synthesis.
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Glycine is one of the three amino acids involved in creatine synthesis via guanidinoacetate in a SAM-dependent pathway (2). Creatine aids the cells in producing ATP, which is energy.
Improves vascular function
Glycine relaxes arteries, causing vasodilation, and it is also part of the structure of hemoglobin, which helps oxygenate tissue better. This will speed up recovery as more nutrients will be able to travel to the tissue which is in need of it, and the waste products, such as lactic acid, can be transported away more effectively. Lactic acid induces inflammation, so getting it out of your muscles faster will aid in faster recovery and put your muscles in the right environment to build muscle.
Boosts growth hormone
Glycine supplementation leads to higher GABA concentration, via activation of the NMDA receptors. (8) GABA increases growth hormone secretion.
Intravenous injection of glycine increases GH in a dose-dependent manner. (3)
Glycine together with glutamine and niacin also enhances GH secretion. (4)
Under conditions of stress and toxins, TRH (thyrotropin releasing hormone) is released to increase TSH (thyroid stimulating hormone). However, prolonged stress can lead to hyper/hypothyroidism. Elevated TRH increases prolactin. Chronic elevated TRH, TSH and prolactin are all antagonistic to thyroid function and are inflammatory. Even a low dose of glycine has been shown to inhibit TSH stimulation from TRH, acting to protect thyroid and keep prolactin low. Stress is good, chronic stress is not. Glycine can help protect your thyroid during periods of stress. Glycine might not lower prolactin, but prevent a stress-induced rise in prolactin, which will keep prolactin levels low. Elevated levels of prolactin are an indication of stress.
Cortisol is a stress hormone. Chronically elevated levels of cortisol are bad, especially if you’re wanting to build muscle. Fortunately, glycine is able to lower cortisol (5) as it increases GABA and is an agonist to the GABA rho 1 receptor (7), and GABA has been shown to lower cortisol. GABA is even a weak glycine receptor agonist and works on synergy with glycine as inhibitory neurotransmitters. (6) Optimal thyroid hormones are anti-stress and adaptogenic, as it makes you more resilient against stressors, thus reducing the need for stress hormones, such as cortisol and cortisone. Increased stress leads to a higher taurine/glycine ratio, showing that both have a protective effect, but that glycine is consumed to fight against elevated cortisol, and should be supplemented during times of stress to prevent a deficiency and stress hormones to do harm.
Glycine is shown to inhibit the function of serotonin. Serotonin is known to cause a “harm avoidance, submissive” behavior, slower metabolism, decreased thyroid function and is also positively associated with estrogen. Although serotonin is important for periods of rapid growth, once the desired growth is achieved, serotonin should be kept low. Before falling asleep, your body temperate drops and your metabolism slows down a bit, this is when anabolic hormones such as testosterone and GH increase. Nutrients are then used for growth, and not for energy during sleep. Serotonin will help with that. Supplementing with tryptophan for accelerating growth for certain periods is the only “excuse” to use it, and once your desired weight is achieved, discontinue tryptophan supplementation. When you wake up, take the GH stack again, but without the tryptophan, as you don’t want elevated serotonin levels throughout the day, as serotonin will also decrease memory forming and learning. I’ll write more on serotonin in a future article.
Amino acids which also interact with the glycine receptors include beta-alanine and taurine, which will also exert a similar effect and may work well in synergy, amplifying the effect of glycine. The mitochondrial can catalyse glycine to form serine and vice versa. Supplementing with serine or phosphatidylserine will have a glycine sparing effect, leaving glycine available for more important tasks.
It’s worth noting that glycine strongly activates 5-alpha reductase for progesterone conversion to allopregnanolone, as mentioned above, then glycine will increase 5-alpha reductase for testosterone conversion to DHT (no human studies on it yet).
Be sure to check out my growth hormone stack here…
I drink some bone broth for my glycine, as collagen/gelatin are the richest sources of glycine. Immediately after drinking a cup of bone broth, my mood, alertness, wakefulness, mental clarity, calmness, assertiveness increase. My mind becomes more clear, and I’m able to be more creative and focused etc… So, for me, it works great.
I’d surely supplement with glycine if I don’t have some broth. Hydrolyzed gelatin does not have the same effect for me and actually has a negative effect on many of my clients. I advise unhydrolyzed gelatin unless you know you are able to tolerate the hydrolyzed version.
Glycine is much cheaper than gelatin, and is generally well-tolerated. Consuming glycine as a whole food might be better than just consuming the isolated amino acid.
Start off with about 500mg glycine a day and work up from there. I don’t think it’s needed to supplement more than 5g daily.
If you don’t feel a difference from a small dose, increase it a bit and see.