Glycine is one of the simplest endogenous amino acids that build proteins, yet its role in the human body reaches far beyond its part in tissue synthesis. It is involved in the functioning of the central nervous system, collagen production, regenerative processes and the regulation of metabolism. In recent years, interest has grown in its potential influence on sleep quality and on the body’s ability to recover, which is reflected in the results of scientific studies.
Contents
- What is glycine?
- Why is glycine so important?
- How does glycine work in the body?
- Glycine and sleep
- Glycine and the nervous system
- Glycine in physically active people
- When is it worth considering glycine supplementation?
- FAQ – frequently asked questions
- What does glycine help with?
- What should glycine not be combined with?
- What are the symptoms of glycine deficiency?
- References
What is glycine?
Glycine belongs to the endogenous amino acids, which means that the body is able to synthesise it on its own. At the same time, in certain situations, for example during intense physical exertion, convalescence or an increased demand for collagen, the amount of glycine produced may prove insufficient in relation to the body’s needs .
It is the smallest of all the protein amino acids. Thanks to its simple structure, it takes part in many biological processes that occur in practically all the tissues of the body. It is one of the basic components of collagen, the protein responsible for the strength of skin, bones, cartilage, ligaments and tendons. It is estimated that about one third of the amino acids making up a collagen molecule is glycine [1,2].
The natural sources of glycine are above all protein-rich foods such as meat, fish, eggs and dairy. Considerable amounts of this amino acid are also found in bone broths and in products containing gelatine. Modern eating habits often limit the consumption of these foods, which is why some people decide to supplement glycine.
Why is glycine so important?
Although for many years glycine was seen mainly as a component of proteins, it is now known that it also acts as a neurotransmitter. This means that it takes part in passing signals between nerve cells. In addition, it is involved in the synthesis of creatine, glutathione and haem, the compound essential for the proper functioning of red blood cells .
How does glycine work in the body?
The variety of glycine’s functions means that it affects many systems of the body at once. Glycine influences processes connected with metabolism, recovery and the functioning of the nervous system.
One of the best understood mechanisms of glycine’s action is its part in inhibiting excessive activity of neurons. In the spinal cord and the brainstem it acts as an inhibitory neurotransmitter, helping to maintain the balance between the excitation and the calming of nerve cells .
The second important mechanism is its effect on the NMDA receptors present in the brain. These receptors are responsible, among other things, for the processes of learning, memory and the plasticity of the nervous system. Glycine acts as a cofactor necessary for their proper functioning, however this effect depends on many other factors and does not mean an automatic improvement of cognitive function after supplementation .
In the body, glycine is also involved in:
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the synthesis of collagen, which is responsible for the proper structure of skin, cartilage and bones;
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the production of glutathione, one of the most important antioxidants in the cells;
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the synthesis of creatine, which takes part in storing energy in the muscles;
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metabolic processes taking place in the liver [2,5].
A growing number of studies also point to glycine’s part in regulating inflammatory processes and protecting cells against oxidative stress .
Glycine and sleep
The influence of glycine on sleep quality is one of the best documented areas of its action. For this reason it is increasingly analysed as an ingredient that supports good sleep hygiene.
Clinical studies suggest that taking about 3 g of glycine before bed may shorten the time it takes to fall asleep and improve the subjective quality of rest in some healthy adults, especially during periods of sleep deprivation [6,7]. The mechanism of this action does not consist in inducing drowsiness similar to that caused by sleeping pills. Instead, glycine probably supports the natural processes responsible for preparing the body for sleep.
Glycine and the nervous system
The nervous system is responsible for coordinating the work of the whole body. Glycine plays many important functions within it, which is why for years it has been the subject of research into brain health, sleep quality and cognitive function.
In the central nervous system glycine plays a dual role. On the one hand it acts as an inhibitory neurotransmitter, limiting excessive excitability of neurons, especially in the spinal cord and the brainstem . On the other hand it takes part in activating the NMDA receptors, which are responsible, among other things, for the processes of learning, memory and brain plasticity .
Such a complex action means that maintaining an appropriate level of glycine matters for proper communication between nerve cells. This does not mean, however, that supplementation will improve cognitive function in every person. The studies carried out so far bring promising results, but experts stress the need for larger clinical trials covering different groups of patients .
Glycine in physically active people
Recovery covers all the processes responsible for rebuilding tissues after physical exertion, injuries and the everyday functioning of the body. Glycine takes part in many of these processes, because it is an important component of numerous proteins and biologically active compounds.
One of glycine’s most important tasks is its part in the production of collagen, the protein responsible for building cartilage, ligaments, tendons and bones, which is why an adequate availability of the basic amino acids is essential for its synthesis .
The second important mechanism is glycine’s part in the production of glutathione – one of the most important antioxidants found in the human body. Glutathione helps protect cells against oxidative stress, which increases during intense physical exertion, infections or chronic inflammation, among other things .
When is it worth considering glycine supplementation?
Taking glycine may be considered by people whose diet provides only small amounts of this amino acid or who want to complement their daily menu in line with their individual needs. It is worth making the decision with the whole lifestyle and state of health in mind.
In studies on sleep quality, the dose most often used was about 3 g of glycine before bed [7,8]. Products containing high doses of glycine in a single serving are available on the market. One example is BestGlycine, which provides 3 g of glycine per serving, that is the amount most often used in scientific studies.
People interested in comprehensive support for the body may also wish to look at the range of BEST LAB food supplements and at the category Supplements for immunity and strengthening, remembering that food supplements are only a complement to a properly balanced diet and a healthy lifestyle.
FAQ – frequently asked questions
Below you will find answers to the questions that come up most often in connection with glycine and its supplementation.
What does glycine help with?
Glycine takes part in many processes that occur in the body. It is involved in the synthesis of collagen, creatine and glutathione, it supports the functioning of the nervous system and it may have a beneficial effect on sleep quality in some people. Studies carried out so far also suggest that it takes part in regenerative processes and in protecting cells against oxidative stress.
What should glycine not be combined with?
No major interactions of glycine with food have been described. Caution should be exercised, however, by people taking medicines that affect the central nervous system, especially if they are planning to start regular supplementation. In the case of long-term treatment or coexisting illnesses, it is worth consulting a doctor or pharmacist beforehand.
What are the symptoms of glycine deficiency?
There is no characteristic set of symptoms that points to glycine deficiency alone. Because the body is able to synthesise it, deficiencies are difficult to identify clearly. An insufficient supply of amino acids or protein in the diet may, however, affect regenerative processes and collagen synthesis.