Glycine

Story

Connected to · 6

synergy · 1

Insomnia
In Yamadera 2007, a small crossover trial, people who took glycine before bed rated their sleep better, fell asleep faster on polysomnography, and felt more refreshed the next morning. One explanation is that glycine widens peripheral blood vessels and lowers core body temperature, a drop that is one of the body's signals for sleep (Bannai 2012; the mechanism comes mainly from animal studies).

cofactor · 4

N-Acetylcysteine
Glutathione is made of three amino acids: glutamate, cysteine and glycine. Cysteine is usually the scarcest ingredient, and N-acetylcysteine (NAC) supplies exactly that; glycine is the last one added. Both affect how fast glutathione can be made.
Collagen peptides
About a third of the amino acids in collagen are glycine, so making collagen each day uses up a good deal of glycine. Some researchers have estimated that the body's own glycine production cannot meet the demand of collagen synthesis; that is the chemical basis for supplementing collagen peptides or glycine, though the estimate has not been tested against health outcomes in people.
Conditionally Essential
The line for "conditionally essential" is drawn on rates, not on the molecule. Meléndez-Hevia 2009 added up an adult's daily glycine use item by item, compared it with the output of the synthesis pathway from serine, and found that production cannot keep up with use. This is a calculated inference that has not been tested against health outcomes in people.
Folate
Glycine is an important source of one-carbon units: when it is broken down or converted, it hands one carbon to folate for making DNA and for methylation.

contrast · 1

Melatonin
They sit on the same sleep-aid shelf but act in different places: melatonin tells the body clock that night has come and helps most with rhythm problems (Zhdanova 2001 found a small dose effective in insomniacs over 50); glycine improved subjective sleep in small trials, possibly by widening peripheral blood vessels and lowering core temperature (Yamadera 2007). Whether taking both adds anything has not been tested; for chronic insomnia, CBT-I is still the first-line treatment.

Read full story

Stop 1/5

Does the body make enough?

EVIDENCEREVIEW 2 · RCT 1

READ THE ORIGINAL

Glycine (abbreviated Gly or G) is the smallest of the 20 amino acids that make up proteins: its side chain is a single hydrogen atom. Because it is so small, it fits where other amino acids cannot, such as the tightest center of the collagen triple helix.

Textbooks list it as non-essential, meaning the body can make it. The question is whether it makes enough. Meléndez-Hevia 2009 (J Biosci) added up the published figures for glycine production and use item by item and estimated that for a 70 kg adult, what the body makes plus what an ordinary diet supplies may fall about 10 g a day short of all its uses. This is an estimate assembled from literature data, not a shortfall measured directly in people.

On that basis, some researchers argue that glycine should count as conditionally essential: the body can make some, but under certain conditions not enough, so food has to make up the rest. Glutamine, arginine, cysteine and tyrosine belong to the same group, a third case outside the textbook split between essential and non-essential.

Educational content, not medical advice — consult a clinician.

Back

Glycine

Story

Connected to · 6

synergy · 1

Insomnia
In Yamadera 2007, a small crossover trial, people who took glycine before bed rated their sleep better, fell asleep faster on polysomnography, and felt more refreshed the next morning. One explanation is that glycine widens peripheral blood vessels and lowers core body temperature, a drop that is one of the body's signals for sleep (Bannai 2012; the mechanism comes mainly from animal studies).

cofactor · 4

N-Acetylcysteine
Glutathione is made of three amino acids: glutamate, cysteine and glycine. Cysteine is usually the scarcest ingredient, and N-acetylcysteine (NAC) supplies exactly that; glycine is the last one added. Both affect how fast glutathione can be made.
Collagen peptides
About a third of the amino acids in collagen are glycine, so making collagen each day uses up a good deal of glycine. Some researchers have estimated that the body's own glycine production cannot meet the demand of collagen synthesis; that is the chemical basis for supplementing collagen peptides or glycine, though the estimate has not been tested against health outcomes in people.
Conditionally Essential
The line for "conditionally essential" is drawn on rates, not on the molecule. Meléndez-Hevia 2009 added up an adult's daily glycine use item by item, compared it with the output of the synthesis pathway from serine, and found that production cannot keep up with use. This is a calculated inference that has not been tested against health outcomes in people.
Folate
Glycine is an important source of one-carbon units: when it is broken down or converted, it hands one carbon to folate for making DNA and for methylation.

contrast · 1

Melatonin
They sit on the same sleep-aid shelf but act in different places: melatonin tells the body clock that night has come and helps most with rhythm problems (Zhdanova 2001 found a small dose effective in insomniacs over 50); glycine improved subjective sleep in small trials, possibly by widening peripheral blood vessels and lowering core temperature (Yamadera 2007). Whether taking both adds anything has not been tested; for chronic insomnia, CBT-I is still the first-line treatment.

Read full story

Stop 1/5

Does the body make enough?

EVIDENCEREVIEW 2 · RCT 1

READ THE ORIGINAL

Glycine (abbreviated Gly or G) is the smallest of the 20 amino acids that make up proteins: its side chain is a single hydrogen atom. Because it is so small, it fits where other amino acids cannot, such as the tightest center of the collagen triple helix.

Textbooks list it as non-essential, meaning the body can make it. The question is whether it makes enough. Meléndez-Hevia 2009 (J Biosci) added up the published figures for glycine production and use item by item and estimated that for a 70 kg adult, what the body makes plus what an ordinary diet supplies may fall about 10 g a day short of all its uses. This is an estimate assembled from literature data, not a shortfall measured directly in people.

On that basis, some researchers argue that glycine should count as conditionally essential: the body can make some, but under certain conditions not enough, so food has to make up the rest. Glutamine, arginine, cysteine and tyrosine belong to the same group, a third case outside the textbook split between essential and non-essential.

Educational content, not medical advice — consult a clinician.