Glycine is a non-essential amino acid, meaning it is produced naturally inside the body and used as a building block for making proteins. Glycine is found in various high-protein foods, including legumes, meat, and dairy products, and sold in its pure form as a dietary supplement.
There is a broad range of reasons people may choose to up their glycine intake. There are numerous benefits to the brain, bones, and muscles and the potential of glycine to help treat various health conditions.
Read on to learn more about the science of glycine and its effects on health.
Uses and Benefits of Glycine
May Improve Muscle Health
Glycine is essential for the production of creatine – a substance found naturally in muscle cells. During high-intensity exercise, muscles utilize an additional source of energy called phosphocreatine. By increasing phosphocreatine, glycine could aid muscle growth by helping muscles take on more load than usual.
Furthermore, creatine helps increase water retention in muscles, a process that’s important for maintaining muscle health and recovery of muscle cells following intense exercise.
In one experiment, scientists exposed muscle cells from mice to chemicals which cause muscles to waste away, also known as muscular atrophy. They found that muscle cells treated with glycine were 20% larger than cells treated with another amino acid, L-alanine. Furthermore, the glycine-treated cells had increased levels of protein synthesis compared to the L-alanine-treated cells. The scientists’ results indicate glycine could help protect muscles from muscular atrophy.
Helps Protect Bones
Glycine increases the production of insulin-like growth hormone 1 (IGF1), a chemical messenger that signals the body to increase the production of bone cells. Glycine also plays an essential role in collagen production – a structural protein that makes up the majority of bone mass.
There is evidence to suggest that higher levels of glycine may be associated with increased bone mineral density – a measure of bone health. However, one study found that increased glycine intake increased the risk of bone fractures in men.
May Be Neuroprotective
Empirical evidence shows that glycine may help protect nerve cells survival by counteracting some of the effects of oxidative stress, a process that causes nerve cell death.
To demonstrate the neuroprotective effects of glycine, scientists shut off the oxygen and glucose supply to mice nerve cells, known to cause oxidative stress, and found glycine reversed some of the neural damage and cell death.
Another experiment in rats also found glycine reduced the level of brain damage following a model of stroke.
Increases Liver Health
Many liver diseases are characterized by a build-up of scar tissue in the liver, known as fibrosis. Researchers have found that glycine in the diet may help prevent fibrosis by shutting down the function of a type of cell called Kupffer cells.
Evidence suggests that glycine may help reverse liver damage caused by alcohol. For example, in a model of alcohol-induced liver damage in rats, glycine increased the activity of antioxidant enzymes, which are proteins that prevent damage by oxidative stress, and reversed alcohol-induced changes in liver fat. However, it’s unknown whether these effects would be the same in human alcohol-induced liver damage.
May Help Treat Diabetes
Diabetes is caused by the body’s lack of ability to respond to insulin – a hormone responsible for telling cells to absorb glucose from the blood.
Scientists have demonstrated that glycine increases the effects of insulin in healthy people, increasing the removal of glucose from the blood, which could be useful in helping to prevent or manage diabetes.
In line with this claim, researchers have found an association between higher levels of glycine in the blood and decreased risk of type 2 diabetes.
In a clinical study, researchers gave type 2 diabetic patients glycine for three months. Following their course of treatment, patients who took glycine had decreased glucose levels in the blood and decreased markers of inflammation, which is a common cause of tissue damage in diabetes.
Can Aid Sleep
In one study, participants who took glycine before bed reported improved sleep quality and length. Furthermore, using polysomnography technology, the researchers showed glycine decreased the participant’s time to fall asleep and the time taken to reach a deep sleep state.
It’s been demonstrated that glycine can shut down the action of orexin-producing cells. Orexin is a neurotransmitter that plays an essential role in keeping us awake during the day, so decreasing orexin production could explain a mechanism by which glycine aids sleep.
Research has shown glycine could decrease the time taken to fall asleep and reach a deep sleep state.
Other mechanisms suggest glycine may be helpful in sleep by aiding the production of serotonin, which is required for the production of the sleep-promoting hormone melatonin.
Furthermore, glycine decreases core body temperature, which, in turn, can help aid sleep as the body associates cooler body temperatures with sleep and warmer temperatures with wakefulness.
May Be Useful for Schizophrenia
One theory about the causes of schizophrenic symptoms is that patients have low levels or low activity of NMDA receptors – a type of receptor in the brain involved in learning and memory.
Because glycine activates NMDA receptors, scientists have proposed it may be useful in schizophrenic treatment. In line with this suggestion, one study found that giving schizophrenic patients high doses of glycine alongside their regular treatment resulted in a 34% decrease in negative symptoms. Therefore, glycine could offer a potential treatment option to help patients manage symptoms.
Side Effects and Safety of Glycine
In published studies on glycine, there have been very few reported adverse side effects.
However, online sources suggest glycine can cause side effects relating to its effect in the gut, such as:
- Nausea
- Vomiting
- Diarrhea
- Stomach pain
A couple of studies suggest that long-term glycine intake could be associated with an increased risk of bladder tumors and stroke. However, the evidence is limited, and many factors beyond glycine could have contributed to the development of these pathologies in the linked experiments.
Glycine Drug Interactions
One study found that glycine decreased the effectiveness of clozapine. Therefore, if you’re currently taking any antipsychotic medication, then you may want to avoid glycine, and you should check with your prescribing physician before taking glycine.
Furthermore, research has found that glycine can interact with GABA-receptors in nerve cells. Therefore, glycine may interfere with drugs that act on GABA receptors, such as benzodiazepines. Because glycine promotes sleep, taking glycine alongside these drugs could also potentially increase their sedative effects.
If you’re considering taking glycine and are already taking a prescription or over-the-counter medication, be sure to consult with a medical professional or pharmacist first, as they will be able to give you expert advice based on your personal needs.
Glycine Dosing
To date, no reported overdoses relating to glycine have been reported.
The standard dose of glycine used in clinical studies is around 3-5 grams per day, although the range of doses administered by researchers has ranged from 1 to 90 grams.
In one study, 90g of glycine per day, spread between 3 doses, led to no significant clinical effects, apart from one patient who reported nausea and vomiting.
It’s difficult to determine a suitable dose of glycine because of the lack of long-term safety studies in human patients.
In a toxicology study in rats, researchers found that 2000 mg/kg of glycine for four weeks, which is well above the average dose, had no adverse effects on the rats, although they did show small changes in their urine.
It’s difficult to determine a suitable dose of glycine because of the lack of long-term safety studies in human patients. Therefore, as with all drugs, we recommend you begin with a small amount and increase your intake by small increments till you find the dose which works best for you.
Final Thoughts on Glycine
Glycine has many valuable functions in maintaining health and could be helpful as an add-on tool for treating liver problems, diabetes, sleep disorders, and schizophrenia. However, more research is needed to determine glycine’s long-term benefits and safety.
If you think you could benefit from increasing your glycine intake, we recommend that you consult with a medical professional first for expert advice.
