Glycine is one of the simplest amino acids that plays a key role in the human body. It is mainly known for its building function in proteins, but its effects go far beyond that. Glycine is involved in collagen synthesis, metabolism, detoxification and regulation of nervous system function. What's more, more and more studies are pointing to 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 is found 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 extremely 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 converting 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 certain amounts of glycine, which is crucial for basic vital functions.
Dietary sources
Although the body can produce glycine on its own, supplying it with food is equally important. High concentrations of glycine are found in:
- Gelatin and collagen: These products are particularly 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: Certain species of fish, especially oily marine fish, also contain significant amounts of glycine.
- Dairy: Dairy products, such as cheese and yogurt, provide dietary glycine.
- Legumes: Beans, lentils and peas are vegetable 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 accounts for about 30% of the total protein mass in the human body. Collagen is crucial to the health of skin, joints, tendons and bones, providing them with flexibility and strength. In the context of protein synthesis, glycine plays a role in the formation of the three-dimensional structure of proteins, which is essential for their proper function.
Metabolic transformations
Glycine is involved in a number of metabolic pathways, including the synthesis of purines, creatine and heme, which are essential for proper cell function. Creatine, synthesized from glycine, is crucial for energy production in muscle and brain. Glycine is also involved in glucose metabolism, which can affect blood sugar regulation and support metabolic health.
Detoxification
Glycine is a component of glutathione, one of the body's most important antioxidants. Glutathione protects cells from oxidative stress and helps with detoxification by neutralizing toxins and heavy metals. Glycine plays a key role in conjugating 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, meaning 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 may support mental health by reducing symptoms of depression and anxiety.
Glycine and health
Joint and bone health
With a key role in collagen synthesis, glycine is important for joint and bone health. Studies have shown that supplementation with collagen, rich in glycine, can improve joint health, reduce pain and stiffness associated with osteoarthritis, and promote 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 elasticity and a youthful appearance. Regular collagen supplementation can improve skin hydration, reduce the appearance of wrinkles and aid skin recovery from injury. Glycine also helps produce keratin, a protein essential for hair and nail health.
Cognitive function and mental health
Acting as an inhibitory neurotransmitter, glycine may improve sleep quality and reduce anxiety. Studies suggest that glycine supplementation may improve cognitive function, particularly in the areas of working memory and ability to concentrate. Glycine may also support mental health by alleviating symptoms of stress and improving mood
Detoxification and oxidative stress
Glycine, being 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
Studies in animal models 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 is associated with lifespan extension in a variety of model organisms, from yeast to mammals. Glycine may also affect pathways related to autophagy, the process by which cells remove damaged components, which is key to maintaining cellular health and longevity.
Clinical studies
Although most of the research on glycine and longevity has been conducted in animal models, there is growing interest in clinical trials in humans. Preliminary research suggests that glycine supplementation can improve metabolic health, reduce the risk of cardiovascular disease and improve overall quality of life in old age. For example, research on glycine in the context of metabolic syndrome has shown that it can improve insulin sensitivity and reduce inflammation.
Potential benefits for the elderly
The elderly may particularly benefit from glycine supplementation, given its potential anti-aging effects, support for joint, bone and skin health, and cognitive function. A regular supply of glycine may support the maintenance of 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 various 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 smoothies, making supplementation simple and convenient.
Dosage and safety
Typical supplementation doses of glycine range from 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 dosages 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 can interact with other supplements and medications, especially those that affect the nervous system. It is important to consult your doctor before starting supplements, especially if you are taking antiepileptic drugs, 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 extremely 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 processes. A growing body of research suggests that glycine may also play a role in aging and longevity, making it of interest to researchers and health-conscious individuals alike. 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.
- Meléndez-Hevia, E., & de Paz-Lugo, P. (2008). Glycine makes vertebrates faster swimmers. Biochemical and Biophysical Research Communications, 376(3), 692-694.
- 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.