What Is Glycine?

This can aid with schizophrenia, enlarged prostate, and leg ulcers

Glycine is an amino acid that functions as a building block for certain proteins, most especially the collagen found in skin, ligaments, muscles, bones, and cartilage. It makes up around 35 percent of the collagen in the human body.

Glycine also helps regulate nerve impulses in the central nervous system, most specifically those of the spinal cord, retina, and the control center of the brain known as the brainstem. Glycine will also bind with toxic substances and aid in their excretion from the body.

Unlike other amino acids that are mainly derived from the foods we eat, glycine can be synthesized in the body and is therefore not considered an essential amino acid. We can obtain all the glycine we need from high-protein foods such as meat, poultry, fish, eggs, dairy, beans, cereals, and pasta.

With that being said, there is evidence that taking a glycine supplement can help treat certain medical conditions, both metabolic and neurological.

Potential Health Benefits of Glycine
Laura Porter / Verywell

What Is Glycine Used For?

Because of its many functions in the body, glycine is believed to offer health benefits if taken in supplement form. Most of the current research has been focused on its role in the central nervous system, where it may be able to improve sleep, enhance memory, and aid in the treatment of schizophrenia.

It is also believed to reduce brain damage following a stroke, treat an enlarged prostate, heal serious leg ulcers, and improve insulin sensitivity in people with diabetes or prediabetes.

Sleep, Mood, and Memory

Glycine stimulates the production of the serotonin, the "feel good" hormone that helps elevate mood, improve sleep quality, and enhance cognition and memory.

While some believe that glycine supplements act as "natural antidepressants," the effect on the brain is relatively short-lasting, causing a transient spike in serotonin levels that quickly dissipates within minutes.

While there is little evidence that this could alter the course of a mood disorder like depression, research suggests that the effect may be enough to influence sleep patterns in people with insomnia.

One study from Japan demonstrated how glycine affects a part of the brain known as the hypothalamus, spurring increased rapid eye movement (REM) consistent with deep sleep. The effect was dose-dependent, meaning that sleep patterns seemed to improve in tandem with increased glycine dosages, usually taken right before bedtime.

While some proponents claim that glycine supplements can improve memory, concentration, and mental performance, there has been little evidence of this on the biochemical level.

Rather, it appears that the improvement of sleep patterns indirectly enhance memory and concentration in the same way it would with anyone who is not sleep deprived.


The transient impact of glycine has on serotonin levels may also benefit people with schizophrenia. Rather than treating the disease itself, glycine appears to reduce the negative side effects of the antipsychotic drugs used in treatment, including Zyprexa (olanzapine) and Risperdal (risperidone).

A 2016 review of studies reported that glycine supplements taken with antipsychotic therapy reduced the incidence of cognitive and physiological side effects by 34%. To do so, however, required relatively high doses (8 milligrams or more) in order for glycine to pass through the blood-brain barrier.

This is problematic since high doses can cause significant side effects, including nausea, vomiting, and diarrhea. To avoid this, healthcare providers will often start with a lower dose and increase the dosage gradually until the desired effect is achieved.

Ischemic Stroke

Glycine is sometimes prescribed to people who have just had an ischemic stroke. Ischemic strokes occur when the arteries to the brain become narrowed or blocked, causing the restriction of blood flow (ischemia) to the brain. The evidence in support of its use has been mixed and often contradictory.

Early research published in the journal Cerebrovascular Disease suggested that a sublingual (under the tongue) dose of glycine given within six hours of a stroke could limit the damage done to the brain.

By contrast, research from Japan suggests that a high intake of glycine might actually increase the risk of death from a stroke, at least in men.

According to a 2015 study from Gifu University, a high-glycine diet can increase the systolic blood pressure by 2 to 3 millimeters of mercury (mmHg) over the course of years, irrespective of the dietary source. In men, this translated to a 66% to 88% increased risk of death by stroke. The same effect was not seen in women.

The contradictory nature of the research suggests that the benefits of glycine may be limited to the acute treatment of—rather than the prevention of—an ischemic stroke.

Enlarged Prostate

There is limited data as to whether glycine supplements can aid in the treatment of an enlarged prostate (also known as benign prostatic hyperplasia or BPH). Much of the evidence is based on the use of a natural supplement called seroitae extract, a glycine-rich compound derived from the Korean black soybean (Glycine max. (L.) Merri).

According to research from the Catholic University in Korea, a 1,400-milligram (mg) dose of seroitae extract given three times daily for 12 weeks reduced symptoms of BPH compared to men provided a placebo.

While some alternative practitioners believe that a daily glycine supplement may help prevent BPH, there is little actual evidence to support these claims.

Leg Ulcers

When applied as a topical cream, glycine may help promote the healing of certain types of leg ulcers. Much of the research dates back to the 1980s when it was found that a topical cream containing glycine helped treat leg ulcers caused by rare disorders such as prolidase deficiency and Klinefelter syndrome.

However, most of the studies were small and poorly designed. Beyond this, there is no real evidence that glycine can aid in the treatment of leg ulcers caused by diabetes, infections, nutritional deficiencies, or vascular diseases.

The only exception may be in the treatment of recalcitrant (non-responsive) ulcers in people with sickle cell disease (SCD). According to a 2014 review of studies, topical glycine ointments provided minimal to modest improvement of SCD ulcers, although none actually cured the wound.

Insulin Resistance

There is a known association between low glycine levels in the blood and the onset of insulin resistance. People with insulin resistance are unable to use insulin effectively, leading to high blood sugar levels and the onset of type 2 diabetes.

Some alternative practitioners believe that by increasing glycine levels with oral supplements, insulin sensitivity can also be increased, normalizing blood sugar levels.

Although the presumption seems fair enough, there is little evidence that the strategy actually works. This is because the low glycine levels are not so much induced by the absence of glycine but rather by the rate at which glycine is metabolized in the liver as diabetes progresses.

As such, insulin resistance spurs the depletion of glycine, rather than the other way around. Increasing the intake of glycine will do little to alter this effect.

Side Effects

Glycine supplements are generally considered safe if taken as directed. With that said, there has been little research into the long-term safety of glycine supplements.

Most people who take glycine will not experience any side effects. Those who do may have mild gastrointestinal symptoms such as an upset stomach, nausea, loose stools, or vomiting.

Glycine supplements are not recommended if you are taking the antipsychotic drug Clozaril (clozapine). Unlike other drugs used to treat schizophrenia, glycine appears to decrease the effectiveness of Clozaril in some people.

Due to the lack of research, glycine should be avoided in children and people who are pregnant or breastfeeding unless otherwise instructed by a qualified healthcare provider.

Glycine capsules
Verywell / Anastasia Tretiak

Dosage and Preparation

Glycine can be found in several different formulations. The most common are oral gel caps, typically available in 500 mg to 1,000 mg doses. There are also powdered formulations that you can add to shakes or smoothies.

While there are no prescribed guidelines for the appropriate use of glycine in people with schizophrenia, many experts recommend 0.4 grams per kilogram of body weight (g/kg) twice daily when taking an atypical antipsychotic like Zyprexa and Risperdal.

Topical creams containing glycine and the amino acids L-cysteine and DL-threonine are available by prescription. Depending on the skin condition, it may be prescribed once daily, twice daily, or every other day.

What to Look For

If considering a glycine supplement for any reason, it is best to speak with your healthcare provider first to ensure you take them correctly and are aware of the risks and benefits of treatment.

When shopping for supplements, always look for brands that have been tested and approved by an independent certifying authority, such as the United States Pharmacopeia (USP), NSF International, and ConsumerLab. Never use a supplement that is expired or appears damaged or discolored.

Other Questions

Do I really need a glycine supplement?

The first question to ask yourself if considering a glycine supplement is, "Do I really need it?" In most cases, you don't. Glycine is found in many of the foods we eat and in more than ample supply.

What foods are good sources of glycine?

Instead of supplements, search for real food sources rich in glycine, measured in grams (g) including:

  • Red meats: (1.5 to 2 g glycine per 100 g)
  • Seeds such as sesame or pumpkin (1.5 to 3.4 g per 100 g)
  • Turkey (1.8 g per 100 g)
  • Chicken (1.75 g per 100 g)
  • Pork (1.7 g per 100 g)
  • Peanuts (1.6 g per 100 g)
  • Canned salmon (1.4 g per 100 g)
  • Granola (0.8 g per 100 g)
  • Quinoa (0.7 g per 100 g)
  • Hard cheese (0.6 g per 100 g)
  • Pasta (0.6 g per 100 g)
  • Soybeans (0.5 g per 100 g)
  • Bread (0.5 g per 100 g)
  • Almonds (0.6 g per 100 g)
  • Eggs (0.5 g per 100 g)
  • Beans (0.4 g per 100 g)

If you need help putting together an appropriate diet based on your current health or weight loss goals, ask your healthcare provider for a referral to a qualified nutritionist or dietitian.

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6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  5. Woong J, Hyo J, Hye C, et al. The effect of Seoritae extract in men with mild to moderate lower urinary tract symptoms suggestive of benign prostatic hyperplasiaEvid Complement Altern Med. 2016; 2016: article ID 1960926. doi:10.1155/2016/1960926

  6. Martí-Carvajal A, Knight-Madden J, Martinez-Zapata M. Interventions for treating leg ulcers in people with sickle cell disease. Cochrane Database Syst Rev. 2014 Dec 8;(12):CD008394. doi:10.1002/14651858.CD008394.pub3