Glycine is one of the simplest amino acids that plays a key role in the human body. It is known mainly for its building block function in proteins, but its effects go far beyond that. Glycine is involved in collagen synthesis, metabolism, detoxification and regulation of the nervous system. What's more, more and more research indicates its potential impact on health and longevity.
What is glycine?
Glycine (Gly) is the simplest of the protein amino acids, having the smallest molecular weight. It occurs in organisms as a free amino acid and as a component of proteins, especially collagen, which is the main structural protein in connective tissue, skin, tendons and bones. Thanks to its simple structure, glycine is exceptionally versatile and easily absorbed by the body.
Synthesis and sources of glycine
Endogenous synthesis
Glycine can be synthesized endogenously in the human body from choline and serine. This process occurs mainly in the liver and kidneys, where the enzymes responsible for the conversion of choline and serine into glycine are particularly active. This means that even without the supply of glycine from food, the body is able to produce some of it, which is crucial for basic life functions.
Dietary sources
Although the body can produce glycine on its own, getting it from food is just as important. High concentrations of glycine are found in:
- Gelatin and collagen: These products are especially rich in glycine and other amino acids that support skin and joint health.
- Meat, especially poultry: Poultry, especially dark meat, is a good source of glycine.
- Fish: Some species of fish, especially oily saltwater fish, also contain significant amounts of glycine.
- Dairy: Dairy products such as cheese and yogurt provide glycine in the diet.
- Legumes: Beans, lentils and peas are plant sources of glycine.
- Spinach and other green vegetables: Green leafy vegetables are also rich in glycine, making them an important component of a vegetarian diet.
Biochemical properties and functions of glycine
Protein synthesis
Glycine is essential for the synthesis of proteins, including collagen, which makes up about 30% of the total protein mass in the human body. Collagen is essential for the health of skin, joints, tendons and bones, providing them with elasticity and strength. In the context of protein synthesis, glycine plays a role in the formation of the three-dimensional structure of proteins, which is necessary for their proper functioning.
Metabolic changes
Glycine is involved in many metabolic pathways, m.in. in the synthesis of purines, creatine and heme, which are essential for proper cell function. Creatine, synthesized from glycine, is crucial for energy production in muscles and the brain. Glycine is also involved in glucose metabolism, which may affect blood sugar regulation and support metabolic health.
Detoxification
Glycine is a component of glutathione, one of the most important antioxidants in the body. Glutathione protects cells from oxidative stress and aids in detoxification by neutralizing toxins and heavy metals. Glycine plays a key role in the conjugation of toxins in the liver, allowing them to be safely removed from the body.
Nervous system
Glycine acts as an inhibitory neurotransmitter in the central nervous system, which means it can reduce neuronal activity and contribute to improved sleep quality, reduced anxiety, and improved cognitive function. Glycine affects NMDA receptors, which are key to memory and learning processes. Additionally, it can support mental health by reducing symptoms of depression and anxiety.
Glycine and health
Joint and bone health
Thanks to its key role in collagen synthesis, glycine is important for joint and bone health. Studies have shown that supplementing with glycine-rich collagen can improve joint health, reduce pain and stiffness associated with osteoarthritis, and aid in cartilage regeneration. Collagen also supports bone mineralization, which is key to preventing osteoporosis.
Skin and hair
Collagen, which contains glycine, is also essential for skin health, contributing to its elasticity and youthful appearance. Regular collagen supplementation can improve skin hydration, reduce the appearance of wrinkles and aid skin regeneration after injury. Glycine also helps produce keratin, a protein essential for healthy hair and nails.
Cognitive Function and Mental Health
By acting as an inhibitory neurotransmitter, glycine may improve sleep quality and reduce anxiety. Studies suggest that supplementing with glycine may improve cognitive function, particularly in the areas of working memory and the ability to concentrate. Glycine may also support mental health by relieving symptoms of stress and improving well-being.
Detoxification and oxidative stress
Glycine, a component of glutathione, helps detoxify the body by protecting cells from free radical damage. Supporting the body’s natural detoxification processes can help improve overall health and longevity. Glycine can also support liver function, which is key to effectively removing toxins from the body.
Glycine and Longevity
Molecular mechanisms
Animal studies have shown that glycine can affect several key metabolic pathways associated with aging, including the mTOR pathway, which regulates cell growth, proliferation, and metabolism. Inhibition of the mTOR pathway has been associated with extended lifespan in a variety of model organisms, from yeast to mammals. Glycine can also affect pathways related to autophagy, the process by which cells remove damaged components, which is crucial for maintaining cellular health and longevity.
Clinical trials
Although most of the research on glycine and longevity has been done in animal models, there is growing interest in clinical trials in humans. Preliminary studies suggest that glycine supplementation may improve metabolic health, reduce the risk of cardiovascular disease, and improve overall quality of life in old age. For example, studies of glycine in the context of metabolic syndrome have shown that it may improve insulin sensitivity and reduce inflammation.
Potential benefits for older people
Older adults may particularly benefit from supplementing with glycine, given its potential anti-aging effects, support for joint, bone, skin, and cognitive health. Regular glycine intake may help maintain health and function in old age. Glycine may also support heart health by reducing homocysteine levels, which are associated with a higher risk of cardiovascular disease.
Glycine supplementation
Forms of supplementation
Glycine is available in a variety of supplement forms, including powder, capsules, and tablets. It is often used as an ingredient in collagen supplements and in its pure form as a dietary supplement. Glycine powder can be easily dissolved in water or added to a smoothie, making supplementation simple and convenient.
Dosage and safety
Typical supplemental doses of glycine are 3 to 5 grams per day, although some studies suggest that higher doses may be beneficial in specific cases. Glycine is generally considered safe, although as with any supplement, it is important to follow recommended doses and consult with a physician before beginning supplementation. Long-term use of high doses of glycine should be monitored to prevent potential side effects.
Interactions with other supplements and medications
Glycine may interact with other supplements and medications, especially those that affect the nervous system. It is important to consult a physician before starting supplementation, especially if you are taking anticonvulsants, antidepressants, or other medications that affect brain function. Glycine may also interact with supplements that affect glucose metabolism, which should be taken into account when planning supplementation.
Glycine is an incredibly important amino acid that plays key roles in the human body, from protein synthesis to regulating nervous system function. Its potential health benefits include improved joint health, skin health, cognitive function, and support for detoxification. A growing body of research suggests that glycine may also play a role in aging and longevity, making it an interesting topic for both scientists and health-conscious individuals. Glycine supplementation, especially when combined with a well-balanced diet, can help improve overall health and quality of life.
Sources:
- Wang, W., Wu, Z., Dai, Z., Yang, Y., Wang, J., & Wu, G. (2013). Glycine metabolism in animals and humans: implications for nutrition and health. Amino Acids, 45(3), 463-477.
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- Banasik, M., Górny, M., & Szczygieł, D. (2020). Glycine supplementation in clinical practice. Journal of Applied Biology & Biotechnology, 8(1), 66-72.
- Rombouts, I., Lagrain, B., & Delcour, J. A. (2012). Role of glycine in the functionality of wheat gluten proteins. Food Chemistry, 131(4), 1016-1021.
- Yoon, M. S. (2017). The emerging role of branched-chain amino acids in insulin resistance and metabolism. Nutrients, 9(6), 570.