What is glycine
Glycine is an amino acid that is found in many proteins. It is called replaceable, that is, it can be synthesized by the body, and not just enter it with food.
The amino acid is involved in the synthesis of DNA and RNA, the production of creatine – a fast fuel for muscles – and the creation of the tripeptide glutathione. The latter protects the body from free radicals – reactive molecules that can damage cell components and lead to their death.
Glycine also works as an inhibitory neurotransmitter. It regulates the activity of nerve cells and, together with glutamate, activates NMDA receptors in the brain, which are associated with learning and memory processes.
Recently, scientists have even discovered special amino acid receptors in the brain that play a role in the occurrence of depressive disorders. But it’s too early to talk about any practical application of this information.
The body receives about 1.5–3 g of glycine per day from meat, fish, dairy products, rice and other protein-rich foods. And about 12–15 mg per kilogram of body weight is produced in the body every hour from other amino acids, mainly serine.
Manufacturers claim that the amino acid can also be obtained from pharmaceutical preparations. In Russia, glycine belongs to the nootropic group of drugs and is sold in 100 mg tablets. The product was even included in the list of vital and essential drugs for medical use for 2024. You can also buy amino acids in the form of dietary supplements, but, as a rule, in a much higher dosage. For example, in capsules of 1,000 mg.
Regardless of its form, glycine is touted as an effective nootropic, that is, a remedy that can improve brain function and affect cognitive function. At the same time, there are doubts that in small doses the substance can penetrate the blood-brain barrier – a layer of cells that protect the brain from microbes and other substances that can cause damage.
Why do people drink glycine?
The supplement is mentioned in clinical guidelines for the treatment of cerebrovascular insufficiency. It is also recommended to take the drug after an ischemic stroke in order to quickly restore brain function.
Glycine is also mentioned in clinical recommendations for the treatment of alcohol withdrawal syndrome as a means to maintain brain function. And in a textbook on narcology it is used as a medication for inducing sleep during withdrawal symptoms.
In the reference book of medications, indications for taking glycine also include psycho-emotional tension in stressful situations, decreased mental performance, and even deviant forms of behavior in children and adolescents.
Among the people, glycine has generally become synonymous with an affordable nootropic, and the phrase “you need to drink some glycine” is used to show that memory and attention are no longer what they used to be. But whether it really helps you sleep better, concentrate, remember, be in a good mood and not get into conflicts is a big question.
Can glycine really improve brain function?
First of all, it must be said that glycine from drugs does not penetrate the blood-brain barrier. There is limited evidence that exogenous glycine can reach the brain, but for this you need to take a really larger dose – about 6-8 g, and intravenously.
Thus, tablets and capsules simply will not be able to provide enough glycine for it to penetrate the brain, much less affect cognitive function.
There is one old study in which scientists tested the effects of the supplement on attention, memory and mood of healthy people. Men of different ages were given a special form of glycine, and then their cognitive functions were tested with various tests. It turned out that the supplement improves episodic memory, especially in middle-aged people, but does not affect concentration and distribution of attention.
In another study, scientists suggested that glycine could improve sleep deprivation. In the experiment, young and elderly men took 3 g of glycine before a short sleep of 5.5 hours, and then filled out questionnaires about their well-being and performed mental performance tests.
On the first day, people who took the supplement felt more alert than those who drank a placebo, but by the third day there were no such differences. Also, glycine did not affect memory and reaction; it only slightly improved psychomotor vigilance.
There are some reports that glycine may slightly improve the condition of people with obsessive-compulsive disorder, and in high doses it may reduce negative symptoms in schizophrenia. But these data are too small to seriously consider the amino acid as a method of therapy for mental disorders.
This is where the evidence for any benefits of the supplement for brain function ends. All authoritative sources of medical information are silent about glycine. Its use as a nootropic has not been tested internationally by Cochrane, a bastion of evidence-based medicine. The World Health Organization does not provide any information, and in the USA glycine is used only as a rinsing solution during urological operations.
Can glycine cause harm?
This is unlikely unless you overdo it with the additive. There is evidence that in a dose of 9 g glycine can cause side effects from the digestive system – abdominal pain and loose stools.
However, in one study, people with schizophrenia were given up to 60 grams of glycine per day, and out of 22 participants, only one left the study due to nausea and vomiting from taking the supplement.
No doctor will prescribe such an amount. The highest doses mentioned in clinical guidelines are 1–2 g per day for ischemic stroke. For other conditions, glycine is taken 100–200 mg 2–3 times a day.
Thus, glycine is unlikely to harm you, but it is also unlikely that this supplement will help you in any way.