Supplement may treat insomnia, enlarged prostate, and other conditions
Glycine is one of the many amino acids that benefits your body. Glycine is important because it: 8 Essential Amino Acids
Glycine may also benefit the following, though evidence is limited and more research is needed:
Unlike some amino acids that must be obtained solely through foods, the body can produce glycine. It is also available in supplement form.
This article looks at glycine supplements' potential benefits and risks and whether the current science supports the health claims. It also offers tips on how to select and use glycine supplements safely.
Dietary supplements are not regulated in the United States, meaning the FDA does not approve them for safety and effectiveness before products are marketed. When possible, choose a supplement that has been tested by a trusted third party, such as USP, ConsumerLabs, or NSF.
However, even if supplements are third-party tested, that doesn’t mean that they are necessarily safe for all or effective in general. Therefore, it is important to talk to your healthcare provider about any supplements you plan to take and to check in about any potential interactions with other supplements or medications.
The benefits of glycine as a supporter of growth and overall health are numerous. It's been claimed that glycine supplementation can prevent and treat disease as well as enhance the quality of sleep and neurological symptoms.
This being said, glycine use should be individualized and vetted by a healthcare professional, such as a registered dietitian, pharmacist, or doctor. No supplement is intended to treat, cure, or prevent disease. Although generally considered safe, there's been little research on long-term use, so check with your healthcare provider before trying it as a new supplement.
Glycine is an amino acid that serves as a building block for specific proteins, including collagen, a structural protein found in connective tissues. Collagen is found in:
Glycine makes up around 33% of the collagen in the human body.
Glycine also helps regulate nerve impulses in the central nervous system. This system affects the spinal cord and the brain. Glycine also binds to toxins so that the body can clear them.
In addition to the glycine already produced by the body, you can also take glycine supplements. Most current research has focused on glycine's role in sleep, mood, stroke, and heart disease.
Glycine stimulates the production of serotonin , the "feel-good" hormone that helps elevate mood, improve sleep, and enhance memory and thinking.
Studies on rodents have demonstrated that glycine supplementation increases serotonin levels. Due to these effects, some people tout glycine supplements as "natural antidepressants." However, more research is needed to determine how long this impact may last versus an antidepressant medication such as a selective serotonin reuptake inhibitor (SSRI).
It's important to note that these were animal studies, and therefore the results may not apply in the same way to humans.
Some research suggests that glycine supplements may improve sleep in people with insomnia. For example, a 2015 study from Japan evaluated why sleep improved in rats after glycine supplementation. To assess the effects, researchers implanted a telemetry unit on the animals. This is a tag that records and reports data such as behaviors like vocalizations and breathing and biological information like heart rate and oxygen levels. After recovery, rats were given either glycine or water.
Those that received glycine had significantly decreased wakefulness and increased non-rapid-eye-movement (NREM) sleep during the first 90 minutes compared with the control group. Researchers concluded that glycine promotes sleep because it alters body temperature and circadian rhythms. Again, scientists did this research on animals, and therefore it is uncertain whether these results would translate to humans. Studies are required to further explain the physiological role of glycine and its therapeutic potential for improving sleep quality.
While there is some evidence that glycine could improve sleep, research has been done on animals or in very small human trials. Thus, the evidence is limited and more research is needed.
Researchers have looked at how glycine might treat schizophrenia, a mental illness that causes delusions, hallucinations, and unusual behavior.
In a 2016 review of studies, researchers found conflicting evidence about glycine's effect on schizophrenia. For example, while some studies reported that glycine supplements taken with antipsychotics reduced the incidence of cognitive side effects, others showed no difference compared to placebo groups. In addition, researchers observed that people needed a relatively high dose to see any results.
While some research exists on glycine's effect on schizophrenia, results are conflicting.
Healthcare providers sometimes prescribe glycine to people who have just had an ischemic stroke. Ischemic strokes occur when the arteries to the brain become narrowed or blocked, causing blood flow restriction (ischemia ) in the brain. The evidence supporting the use of glycine for this is mixed.
A study in 2020 concluded that glycine improved ischemic stroke by regulating glucose metabolism, inflammatory response, and the shedding of damaged cells. However, a 2015 population study from Japan looked at glycine and stroke mortality in 29,079 Japanese adults. According to the survey, a high-glycine diet raised the systolic blood pressure (the higher number in a blood pressure reading) to such a degree in men that it increased the risk of death from stroke. The same was not seen in women.
This more recent study contradicts an earlier study, indicating that high amounts of glycine might protect the body and lower the risk of death from stroke, at least in some people.
The evidence for glycine after a stroke is conflicting and inconclusive.
Glycine is anti-inflammatory and antioxidative (meaning it prevents or slows cell damage), which are properties that reduce heart disease risk. Therefore, some researchers have looked at the connection between glycine and heart disease.
In a 2015 study in the Journal of the American Heart Association, researchers looked at the association between glycine plasma levels and acute myocardial infarction (heart attack). This population study evaluated 4,109 people who had elective coronary angiography to diagnose stable angina (a blockage in the coronary artery).
The study found that those with higher plasma glycine levels had a more favorable heart disease risk profile and a decreased risk of a heart attack.
While the study is promising, research on the topic is limited.
Glutathione is an antioxidant found in every cell in the body. It's made in the liver and has many important roles including regenerating Vitamins E and C, helping certain enzymes function and supporting the immune system. Research has shown it can slow cancer progression and reduce cell damage caused by other diseases. One of the amino acids needed to produce glutathione is glycine.
The role of supplemental glycine in supporting glutathione synthesis has been studied extensively. Results show it can increase the level of cellular glutathione, especially in those who consume diets relatively low in protein. Additionally, as these levels decline naturally with age, glycine supplementation would have numerous benefits in the elderly population.
In addition to the potential health benefits listed above, some people use glycine to support:
Your healthcare provider may recommend you take glycine to support your sleep or mood or lower your heart disease or stroke risk. However, consuming a supplement like glycine may have potential side effects.
Glycine supplements are generally considered safe if used as directed. However, there has been little research into the long-term safety of glycine supplements.
Most people who take glycine will not experience any side effects, but some may have gastrointestinal symptoms such as:
Since studies have found that glycine supplements interact with antipsychotic drugs, like Clozaril (clozapine), you should talk to a healthcare provider before taking glycine if you are taking these medications. As a general rule, it's best to speak to a healthcare provider before trying any new medications or supplements.
In addition, unless instructed by a healthcare provider, the following people should avoid glycine:
It is essential to carefully read the ingredient list and nutrition facts panel of a supplement to know which ingredients and how much of each ingredient is included. In addition, review this supplement label with your healthcare provider to discuss any potential interactions with foods, other supplements, and medications.
Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs.
Glycine is available in several different formulations. The most common is oral gel caps, typically available in 500 milligrams (mg) to 1,000 mg doses. There are also powdered formulations that you can add to shakes or smoothies.
There are no guidelines for the appropriate use of glycine in people with schizophrenia. Some research is based on a dosage of up to 30 grams daily when taking an atypical antipsychotic. However, always discuss glycine supplementation and dosage with a healthcare provider first.
Topical creams containing glycine and the amino acids L-cysteine and DL-threonine are available by prescription for leg ulcers. Depending on the circumstance, they may be prescribed once daily, twice daily, or every other day.
Glycine toxicity from supplements is rare. However, it can occur when used with sterile water for bladder irrigation. In this situation, a healthcare provider administers glycine, usually after prostate or bladder surgery, to prevent or flush out blood clots.
Signs of glycine toxicity include:
Glycine toxicity can be fatal.
Store glycine supplements and powders in a cool, dry place. Never use a supplement that is expired or appears damaged or discolored. Speak with a healthcare provider before using any supplement for medical reasons.
Glycine is readily available in plenty of foods. You can also take it in supplement form.
You can find glycine in high-protein foods. Good sources of glycine-rich foods include legumes, fish, dairy, and meat.
Some of the best food sources of glycine include:
Glycine supplements come in capsules or powder formulations. Some people prefer capsules because they are easy to take. Others incorporate powders into shakes or smoothies.
Supplements are typically vegetarian or vegan. However, read the label carefully for allergens like wheat or eggs if you have food allergies.
Glycine is an amino acid produced by the body that is important for building collagen, transmitting nerve impulses, and clearing toxins from the body. Some people contend that glycine supplements can enhance many of these functions and, in turn, prevent or treat certain medical conditions.
To date, the evidence of this is weak. Despite claims to the contrary, there is little evidence that glycine supplements can prevent diabetes, relieve insomnia, heal wounds, treat an enlarged prostate, or reduce the risk of death from stroke. They may reduce the risk of side effects from certain schizophrenia medications, but more research is needed.
Glycine supplements are generally considered safe but may cause diarrhea, nausea, upset stomach, and vomiting. Speak with your doctor before using supplements for any medical reason.
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Ding Y, Svingen GF, Pedersen ER, et al. Plasma glycine and risk of acute myocardial infarction in patients with suspected stable angina pectoris. J Am Heart Assoc. 2015;5(1):e002621. doi:10.1161/JAHA.115.002621
McCarty MF, O'Keefe JH, DiNicolantonio JJ. Dietary Glycine Is Rate-Limiting for Glutathione Synthesis and May Have Broad Potential for Health Protection. Ochsner J. 2018;18(1):81-87.
Pei JC, Luo DZ, Gau SS, Chang CY, Lai WS. Directly and indirectly targeting the glycine modulatory site to modulate nmda receptor function to address unmet medical needs of patients with schizophrenia. Front Psychiatry. 2021;12:742058.doi:10.3389/fpsyt.2021.742058
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By James Myhre & Dennis Sifris, MD Dennis Sifris, MD, is an HIV specialist and Medical Director of LifeSense Disease Management. James Myhre is an American journalist and HIV educator.
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