Glycine is the smallest possible amino acid and is found in small quantities in most proteins. Glycine itself is not an essential amino acid as it can be biosynthesized from another amino acid, from Serine.
Amino acids are used by the body to make functional proteins such as neurotransmitters, hormones and enzymes.
Although only found in small quantities in most proteins, glycine is found in high concentrations in collagen, a superfamily of proteins that play key roles in the skin, joints, ligaments, and cartilage. Approximately one third of collagen is glycine and it is a key building block that gives collagen its unique properties.
Glycine can also behave as a neurotransmitter itself and is used by the brain particularly in the brainstem and the spinal cord. Here, glycine relays various motor and sensory functions as well as being involved in crucial memory and learning processes.
Glycine Health Benefits
Glycine supplements have numerous benefits, including:
- Useful adjunct to antipsychotic drugs in the treatment of schizophrenia
- May help control blood sugar levels in type-2 diabetes
- May limit brain damage caused by ischemic stroke
- Protects the liver and kidney from alcohol damage
- Glycine, in the form of a cream, may help with leg ulcers
- Improvement of memory and learning
- Enhanced athletic performance
- Help build lean muscle mass
Glycine and Cognition
In the brain, there are a group of receptors called N-methyl-D-aspartate (NMDA) receptors that can only be properly activated when both glutamate and glycine bind to it. When activated, calcium and sodium ions can be allowed passage into the cell, which can then start various important signaling pathways.
Important signaling pathways that are dependent on NMDA receptor activation include cognition and synaptic plasticity, which is important for memory and learning.
Glycine supplementation has been notably associated with boosting memory and learning processes. Studies on glycine supplementation have shown that glycine can significantly improve the retrieval of memories as well as helping maintain focus and attention.
Therefore, glycine supplementation can help individuals who are engaged in work situations, such as those where mental performance is important. Alternatively, glycine can also benefit individuals, where mental performance is affected, such as during jet lag or shift work, where the brain is affected due to sleep disturbances.
Glycine and Muscle Growth
Glycine is an important amino acid in athletic performance due to its necessary role in creatine metabolism. Glycine, in addition to two other amino acids—arginine and methionine—are required to synthesize creatine, a natural energy source used by the muscles.
Glycine supplementation can therefore assist athletes, sportsmen and women, and bodybuilders, who are undergoing progressive training due to its beneficial effect on creatine synthesis. Creatine improves muscle performance and can this way help the body to build lean muscle.
In addition, during calorie restriction, glycine supplementation has been shown to naturally accelerate fat loss and prevent muscle loss during these times.
In one study, researchers showed that glycine supplementation could be useful as a natural muscle preserver during diets, as it can help to increase or regulate the energy expenditure.
Glycine and Prevention of Age-Related Muscle Loss
As people age, there are major changes in body composition with a gradual loss of muscle mass and strength. Age-related loss of muscle is referred to as sarcopenia and this has a significant negative effect on mobility and physical function in the elderly.
The declining muscle mass and the deterioration in muscle quality in the upper and lower limbs are major factors in not only the loss of mobility status but also maintenance of balance. Frailty and bone fractures from falls are increasingly prevalent with age and significantly contribute to disability and mortality rates.
In one study, glycine supplementation has shown to stimulate serum levels of growth hormone, when compared to placebo. This increase in growth hormone release can improve the anabolic state in middle-aged and elderly individuals, which results in increases in lean body mass.
No matter, if muscle loss is a result of ageing or a result of heavy training, glycine supplementation can help in both cases to lose fat and maintain muscle mass.
Glycine and Joint Health
Glycine is found in high concentrations in a group of fibrous proteins called collagen. Collagen is found in the connective tissues, such as in articular cartilage. In articular cartilage, collagen accounts for almost two-thirds of the dry weight and is responsible for the strength and shock absorbing properties of this tissue.
Supplementation with glycine can help optimize collagen biosynthesis, which protects joints, prevents arthritic pain, and improve joint functionality. Therefore glycine, in addition to other natural joint support supplements, can help maintain joint health and improve joint mobility.
Glycine and Sleep Quality
Glycine has many important functions in the brain and has been observed to help improve sleep quality as well as the time it takes to get to sleep, known as sleep latency.
A double-blind crossover study showed that women who supplemented with glycine had improved sleep quality when taken one hour before bed. In another study, glycine supplementation also significantly reduced sleep latency before falling asleep.
Together, glycine supplementation has shown to improve daytime fatigue and improve cognition scores due to better sleep quality. Subjects also reported waking up feeling refreshed, lively and with a clear head.
Glycine and Diabetes
High blood sugar levels (known as hyperglycemia) are a result of insulin resistance and this is a defining characteristic of type-2 diabetes. People with type-2 diabetes cannot control their blood sugar levels because insulin no longer works as effectively as it should, which can cause a number of serious medical issues.
People who are diagnosed with type-2 diabetes are normally advised to start a healthy diet and to engage in more exercise. In addition, pharmacotherapy—such as using metformin—is also prescribed to help improve insulin sensitivity as well as reducing the amount of glucose produced in the liver.
A natural alternative to help control high blood sugar levels is to supplement with the amino acid glycine. Supplementation with glycine has been shown to lower the release of the hormone glucagon, which releases glucose from the liver to the blood.
In one particular study, it was shown that a high-dose of 40 to 50 grams of glycine daily could reduce the blood sugar level in both healthy and diabetic individuals. More recently, another study showed that glycine helped diabetic patients, who were experiencing auditory neuropathy (hearing loss) by improving hearing acuity.
Glycine and Schizophrenia
Schizophrenia is a major mental disorder that is characterized by abnormal thinking, enhanced emotional responsiveness and altered brain functioning.
The underlying pathophysiology is poorly understood, but it is hypothesized to be associated with the under-activity of a brain signaling system that involves glutamate and the NMDA receptor.
Glycine can bind to the NMDA receptors and this is the basis of how glycine may help in cases of schizophrenia. NMDA receptors are unique in that they require two agonists to stimulate their signaling response: glycine and glutamate. Glutamate elicits the response, while glycine controls the levels of that response.
Glycine supplementation has been shown to enhance the efficacy of drugs used to treat schizophrenia. At high doses, glycine supplements act as an adjunct to more traditional antipsychotic drugs. In these cases, glycine treatment was observed to significantly decrease negative symptoms as well as increase positive feelings.
Glycine acts as adjunct to antipsychotic drugs and in one clinical trial, glycine supplementation was given to patients, who were currently being treated with olanzapine or risperidone. Clinical assessments showed that these drugs efficacies were augmented with the addition of glycine to their daily medication.
However, it must be noted that glycine supplementation should not to be used with the antipsychotic, clozapine. Glycine significantly altered the efficacy of this drug and caused an increase in negative emotions.
Who Should Use Glycine?
Glycine supplementation has many direct and indirect properties that can be of benefit to the following people:
- To help sportsmen and women build lean muscle mass and prevent muscle loss
- To assist the elderly by preventing muscle wasting associated with aging
- To help people combat minor sleep disturbances
- To help those who want to enhance memory and learning performance during shift work
- To enhance cognition during jet lag
- To help people who have joint pain associated with ageing, injury or osteoporosis
- To help diabetics control their blood sugar levels
- To improve the efficacy of antipsychotics in those who have schizophrenia
Glycine Side Effects
For most, glycine supplementation is safe, however, excessive dosages of up to 60 grams per day can cause:
- Stomach upset
Glycine is an amino acid that is found in protein and is reported to not have many known interactions, except for:
- Clozapine/Clozaril and antipsychotic drug used to treat severe schizophrenia
The following combinations can help provide extra health benefits:
- Glycine often comes bound to minerals such as zinc and magnesium, because this makes the minerals easier to be absorbed compared to the free form.
- Glycine, glutamine and niacin can together help to enhance memory function in the elderly
- The amino acids glycine, methionine and arginine can help to boost the creatine synthesis
- Can be used in conjunction with certain types of antipsychotic drugs that are used to treat schizophrenia (except for clozapine)
Glycine reduces oxidative stress caused by metabolic syndrome
Uncontrolled glucose metabolism and increased oxidative damage from excessive abdominal fat contributes to metabolic syndrome. In one study, 60 volunteers were prescribed either a glycine supplement or a placebo to determine whether glycine could help protect the body from oxidative damage.
Oral supplementation with 15 grams glycine daily caused a significant 25% decrease in reactive species that are a result of excess abdominal fat. This shows that glycine plays an important role in balancing the redox reactions in the human body and protects against oxidative damage in patients with metabolic syndrome.
Glycine supplementation ranges of 1 to 3 gram daily. However, some studies have shown that 15-45 grams supplementation has no apparent side effects.
Although glycine is non-toxic, care should be taken if you are pregnant and breastfeeding as this has not been fully researched.
Foods Highest in Glycine
High protein foods such as meat, fish, dairy products and legumes Estimated that around 2 grams of glycine come from food sources
Why Take Glycine
Glycine supplementation has the following health benefits:
- As an adjunct to drugs used to treat schizophrenia to enhance their efficacy
- To improve cognition, memory and learning
- To stabilize blood sugar levels and lower the risk of symptoms associated with type-2 diabetes
- To promote muscle growth through improved creatine biosynthesis
- To assist collagen biosynthesis, which is the main structural unit in skin
- To assist collagen biosynthesis in the repair of connective tissues throughout the body’s joints such as ligaments, tendons and cartilage
- To improve sleep quality and reduce sleep latency
- To combat oxidative damage associated with excessive abdominal fat in metabolic syndrome
Other Names of Glycine
Glycine, GLY, G, aminoethanoic acid, aminoacetic acid, or glycocoll
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