What Should You Know About Glycine Supplements?

Many molecules that decline as we get older tend to have important roles in health maintenance and disease onset. One such molecule is glycine. During aging, glycine levels decline. Recent findings claim that glycine may reverse some aspects of the aging process and may even provide value in lifespan extension.

Key takeaways:
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    Glycine is a non-essential (can be produced by the body) amino acid that is involved in many important cellular processes.
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    Glycine is required in the natural production of glutathione, creatine, and collagen.
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    Glycine decreases as we age, and decreases are associated with the development of aging-associated disorders.
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    Glycine supplementation may provide positive effects against aging and promote lifespan extension.
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    Glycine, is generally, regarded as safe but consult with a doctor before supplementation with high doses.

Compared to other common supplements, glycine is not yet well-known to the public. Here, we cover the benefits and uses of glycine and its connection with longevity.

What is Glycine?

Glycine is one of the most abundant amino acids in the body, with an important function in many cellular processes. Across all amino acids, glycine is the smallest and simplest in terms of its structure, with a chemical formula NH2‐CH2‐COOH. It is naturally produced by the body and is also available in protein-rich foods, such as meat.

Glycine in our body

Amino acids are generally classified into essential (cannot be produced by the body) and non-essential (can be produced by the body). Although glycine is categorized as non-essential, glycine has multiple roles contributing to proper bodily processes and functions. As such, its dysregulation may lead to the development of several disorders.

Glycine in the production of powerful antioxidant

Humans have a built-in antioxidant system to combat free radicals and oxidative stress. Glutathione, the most potent antioxidant in our body, is associated with health. Through aging, glutathione levels drop, which may lead to increased free radical levels, uncontrolled molecular damage, and certain disorders.

Glycine is required in glutathione synthesis, so adequate glycine levels may aid in combating some age-associated diseases related to free radical damage.

Glycine in creatine

Another important compound dependent on glycine for its production is creatine. Creatine is an amino acid concentrated primarily in the muscle and brain. Creatine is utilized during activities requiring short bursts of energy, like sprints and strength-based exercises.

Since glycine can increase our natural creatine production, its potential to boost energy, strength, and performance has significant implications for the elderly.

Collagen and glycine: the main Amino acid?

Glycine is the most abundant amino acid in collagen, wherein every third amino acid in its structure is composed of glycines. Collagen has a very direct impact on aging, especially on visible signs of aging like wrinkles.

Wrinkles are caused by very low collagen, which causes the skin to lose its elasticity.

Glycine and sleep quality

Research in glycine further uncovered the impressive effects of glycine on sleep quality. Notably, experiments show that glycine supplementation can make people enter deep sleep faster, significantly reduce fatigue, and reduce drowsiness during the day. In addition, data have also demonstrated increased serotonin levels and improvement of insomnia symptoms with glycine intake.

Glycine and liver protection

The liver is the source of our natural glutathione production. The liver can regenerate but chronic damage and age-associated degradation negatively impact liver health. As a result, liver diseases such as fatty liver, hepatitis (inflammation), or cirrhosis (scarring) may develop over time.

In mouse models of liver diseases, glycine supplementation was successful in alleviating liver injury, and protecting against alcohol-induced damage, and was shown to increase survival rates.

Glycine and heart protection

Cardiovascular diseases become more common as people age. Poor levels of glycine are associated with coronary heart disease and acute myocardial infarction. It is also suggested that those with heart failure have 10 years shorter life span than those without.

Fortunately, studies have demonstrated the potential therapeutic effects of glycine in reducing the risks of heart diseases.

Glycine and type 2 diabetes (T2D)

Glycine levels are negatively correlated with obesity, insulin resistance, and T2D development. Patients with T2D consistently present with low glycine levels. Interestingly, eating fish, a major source of dietary glycine can lower the risks of T2D.

Further investigations found that glycine can reduce blood sugar levels and stimulate insulin secretion.

Glycine and muscle

Sarcopenia, or muscle wasting due to loss of skeletal muscle mass, is a hallmark of aging. Glycine is well-researched for its ability to help build or maintain lean muscle mass.

High-glycine diets may be an effective nutritional strategy to prevent aging-associated disorders like muscle wasting and physical frailty.

Glycine supplements

Although glycine is naturally produced by the body, glycine declines with age. To combat the health ramifications of glycine deficiency, supplementation is a great way to improve circulating glycine blood levels. So, what’s the proper way to take glycine?


Supplement formulations are more beneficial when higher amounts of glycine intake are desirable. However, there are no standards on glycine dosage. Further, in the USA and Europe for example, supplements are regulated by the FDA only as food, without strict compliance policies in place regarding safety and effectiveness.

Thus, numerous glycine products are available in the market. Products tested by third parties like USP, NSF, or ConsumerLab may be a better option, yet, like almost all supplements, safety and effectiveness are still not guaranteed.

Glycine usage (when to take, how much to take)

Glycine supplements are available in different formulations. Dosages typically range from 500 mg to 3000 mg. It’s usually marketed in capsules, fluids, or powders, and it is taken orally. Consult a physician to determine which is best for your condition.

There’s no general rule on when glycine is taken; however, when used for medical treatment, your doctor may provide timing guidelines.

Glycine while pregnant

Studies suggest that natural glycine production in late-stage pregnant women may be insufficient to support the growing baby, and it becomes indispensable at this stage. Gestating mothers should obtain more glycine from their diet. However, safe and effective glycine dosage for pregnant women is still not established.

According to the Brigham and Women's Hospital and other sources, pregnant and breastfeeding women should not consume glycine supplements. If you’re pregnant or breastfeeding, it is important to consult and discuss your situation first with your healthcare provider.

Foods and drinks

Glycine can also be obtained from natural dietary sources, particularly meat. Good dietary sources of glycine include:

  • Seafood;
  • Poultry;
  • Meat;
  • Eggs;
  • Liver.
  • Pork and chicken skin;
  • Legumes;
  • Dairy;
  • Gelatin;
  • Bone broth.

Glycine and longevity

Scientists claim multiple health benefits of glycine against aging-associated disorders as discussed above. Increasing evidence from in vitro and in vivo studies has tried to validate the anti-aging significance of glycine, but the data are still sparse. However, the proposed mechanisms seem rational.

In addition to the fact that glycine drops as we age since glycine is required in the synthesis of glutathione, creatine, and collagen, its direct impact on oxidative stress, frailty, or wrinkles makes sense.

Via glycine modulation, scientists claimed to reverse the aging process in experimental human cell lines. Another interesting glycine experiment is that when fibroblast cells are taken ~97-y/o elderly were treated with glycine, the researchers observed reinvigoration of mitochondria, our cellular energy machinery, comparable to a younger state. In various organisms like fruit flies, worms, or even mammals, glycine supplementation can also promote lifespan extension.

Side effects

Usually, most people do not experience side effects from glycine supplementation. However, some people may respond to it differently. In some cases, they may experience nausea, vomiting, drowsiness, or an upset stomach.

Is glycine safe?

When used as directed, glycine supplementation is generally considered safe.

Data on the safety of long-term glycine supplementation are also scarce. However, in terms of dosage, some research on high-dose glycine supplementation (15–60 grams) for chronic disorders like mental conditions reported no side effects. But, it is crucial to seek a doctor’s supervision for high-dose supplementations.

Importantly, some drugs may interact with glycine, so if you’re taking other medications, consult your physician.


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