Glycine: benefits, side effects, dosage and interactions


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

Glycine also helps regulate nerve impulses in the central nervous system, especially in the spinal cord, retina , and the brain control center known as the brainstem . Glycine also binds to toxic substances and promotes their elimination from the body.

Unlike other amino acids, which are derived primarily from the food we eat, glycine can be synthesized in the body and is therefore not considered an essential amino acid. We can get all the glycine we need from protein-rich foods like meat, poultry, fish, eggs, dairy products, beans, cereals, and pasta.

That said, there is evidence that taking a glycine supplement can help treat certain diseases, both metabolic and neurological.

Laura Porter / Get Medication Information

What is glycine used for?

Due to its many functions in the body, glycine is believed to provide health benefits when taken in supplement form. Most of the current research has focused on its role in the central nervous system, where it can improve sleep, improve memory, and help treat schizophrenia.

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

Sleep, mood and memory

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

While glycine supplements are believed by some to act as "natural antidepressants," the effect on the brain is relatively short-lived, causing a short-term spike in serotonin levels that quickly wears off within minutes.

While there is little evidence that it can change the course of a mood disorder such as depression, research suggests that this effect may be enough to affect sleep patterns in people with insomnia.

A study from Japan showed how glycine affects a part of the brain known as the hypothalamus, inducing rapid eye movement (REM) in accordance with deep sleep. The effect was dose dependent, meaning that sleeping patterns seemed to improve alongside higher doses of glycine, usually taken just before bedtime.

While some advocates argue that glycine supplements can improve memory, concentration, and mental performance, there is little biochemical evidence to support this.

Rather, it appears that improving sleep patterns indirectly improves memory and concentration in the same way that anyone deprived of sleep does.


The short-term effects of glycine on serotonin levels can also benefit people with schizophrenia . Rather than treating the disease itself, glycine appears to reduce the negative side effects of antipsychotic drugs used in treatment, such as zyprexa (olanzapine) and risperdal (risperidone).

A 2016 review of studies found that glycine supplements taken with antipsychotic therapy reduced the incidence of cognitive and physiological side effects by 34%. However , this required relatively high doses (8 milligrams or more) for glycine to cross the blood-brain barrier .

This is problematic because high doses can cause serious side effects, such as nausea, vomiting, and diarrhea. To avoid this, healthcare providers often start with a lower dose and gradually increase the dose until the desired effect is achieved.

Ischemic attack

Glycine is sometimes prescribed to people who have just had an ischemic stroke . Ischemic stroke occurs when arteries to the brain become narrowed or blocked, restricting blood flow (ischemia) to the brain. The evidence supporting its use has been mixed and often contradictory.

A preliminary study published in the journal Cerebrovascular Disease showed that a sublingual (under the tongue) dose of glycine given within six hours of a stroke can limit brain damage .

In contrast, studies from Japan show that high glycine intake can actually increase the risk of death from stroke, at least in men.

According to a 2015 study from Gifu University, a diet high in glycine can raise systolic blood pressure by 2-3 millimeters of mercury (mmHg) for many years, regardless of the food source. In men, this translates to a 66% to 88% increased risk of death from stroke. In women, the same effect was not seen.

The controversial nature of the study suggests that glycine benefits may be limited to acute treatment rather than prevention of ischemic stroke.

Enlarged prostate

There is limited data on whether glycine supplements can help treat 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 Korean black soybeans ( Glycine max. (L.) Merri).

According to a study from the Catholic University of Korea, a 1,400 milligram (mg) dose of seroitae extract taken three times a day for 12 weeks reduced BPH symptoms compared to men taking a placebo .

Although some alternative practitioners believe that taking glycine daily can help prevent BPH, there is little real evidence to support these claims.

Leg ulcers

When used as a topical cream, glycine can help heal some types of leg ulcers. Much of the research dates back to the 1980s, when a topical cream containing glycine was found to help treat leg ulcers caused by rare conditions such as prolidase deficiency and Klinefelter syndrome .

However, most of the studies were small and poorly designed. Beyond that, there is no real evidence that glycine can help treat leg ulcers caused by diabetes, infections, malnutrition, or vascular disease.

The only exception would be the treatment of persistent (refractory) ulcers in people with sickle cell anemia (SCD) . According to a 2014 review of studies, topical glycine ointments provided minimal to moderate improvement in SCD ulcers, although none of them actually healed the wound .

Insulin resistance

There is a known link between low blood glycine levels and the development of insulin resistance . People with insulin resistance cannot use insulin effectively, leading to high blood sugar levels and the development of type 2 diabetes.

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

While this seems fair enough, there is little evidence that this strategy actually works. This is because low glycine levels are not so much due to a lack of glycine as to the rate at which glycine is metabolized in the liver as diabetes progresses.

Therefore, insulin resistance contributes to the depletion of glycine stores and not the other way around. Increasing your glycine intake will have little effect on this effect.

Side effects

Glycine supplements are generally considered safe when taken as directed. That said, little research has been done on the long-term safety of glycine supplements.

Most people who take glycine do not experience side effects. Sufferers 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 medications used to treat schizophrenia, glycine appears to reduce the effectiveness of clozaril in some people.

Due to a lack of research, the use of glycine in children and pregnant or lactating individuals should be avoided, unless otherwise directed by a qualified healthcare provider.

Get Drug Information / Anastasia Tretyak

Dosage and preparation

Wisteria can be found in a number of different forms. The most common oral gel capsules are usually available in doses ranging from 500 mg to 1000 mg. There are also powdered formulations that can be added to shakes or shakes.

Although there are no prescribed guidelines for the proper use of glycine in people with schizophrenia, many experts recommend 0.4 grams per kilogram of body weight (g / kg) twice daily when taking atypical antipsychotics such as zyprexa and risperdal.

Topical creams that contain glycine and the amino acids L-cysteine and DL-threonine are available by prescription. Depending on the condition of the skin, it can be administered once a day, twice a day or every other day.

What to look for

If for any reason you are considering taking glycine supplements, it is best to speak with your healthcare provider first to make sure you are taking them correctly and to understand the risks and benefits of treatment.

When buying supplements, always look for brands that have been tested and approved by an independent certification body, such as the United States Pharmacopeia (USP), NSF International, and ConsumerLab. Never take an expired supplement that appears damaged or discolored.

Other questions

Do I really need a glycine supplement?

The first question to ask yourself when considering a glycine supplement is "Do I really need it?" In most cases, this is not the case. Glycine is found in many foods we eat and there is more than enough of it.

What Foods Are Good Sources of Glycine?

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

  • Red meat: (1.5 to 2 g of 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)
  • Soy beans (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 preparing a diet suitable for your current health or weight loss goals, ask your doctor for a referral to a qualified dietitian or nutritionist.

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