Glycine is a non-essential amino acid, meaning the human body can produce it naturally. It is present throughout the body and plays an important role in numerous biological processes. This molecule is involved in the creation of proteins, peptides, and various other biomolecules.
What is Glycine
Glycine is the smallest amino acid, featuring only a single hydrogen atom as its side chain. While the body can synthesize glycine, primarily from other amino acids like serine, threonine, and choline, dietary intake can also contribute.
Its compact structure provides flexibility, allowing it to fit into tight spaces within proteins. This is important for the structural integrity and function of proteins. Glycine’s simplicity also plays a role in initiating protein synthesis, as it is often the first amino acid incorporated into a new protein chain.
Where Glycine Comes From
The body obtains glycine from internal production and dietary intake. Internal synthesis primarily occurs from other amino acids like serine, threonine, choline, and hydroxyproline, with the liver and kidneys involved in this process.
Dietary sources include protein-rich foods. These include meats (especially cuts with connective tissue, skin, or bones), fish, dairy products (milk, yogurt, cheese), and legumes (soybeans, peanuts, peas, lentils). Bone broth and gelatin are rich sources due to their high collagen content.
How Glycine Functions in the Body
Glycine serves as a building block for proteins, incorporating into polypeptide chains. It is a component of collagen, the most abundant protein in the human body, found in skin, bones, tendons, and connective tissues. Glycine’s small size allows it to fit into collagen’s tight triple helix structure, contributing to its stability, strength, and flexibility.
This amino acid also acts as an inhibitory neurotransmitter in the central nervous system, especially in the spinal cord and brainstem. It helps regulate neuronal activity, influencing sleep, mood regulation, and motor control.
Glycine is a precursor for glutathione, an antioxidant that protects cells from damage. Maintaining adequate glycine levels is important for glutathione, especially as natural levels can decline with age. It is also involved in the synthesis of creatine, a molecule for energy storage in muscle and brain tissue. Creatine supports muscle function and may have neuroprotective effects.
Glycine participates in other metabolic pathways. It is involved in the synthesis of bile acids, which aid in lipid digestion and absorption. Glycine also contributes to the formation of purines (components of DNA and RNA) and heme (found in red blood cells).
Using Glycine as a Supplement
Glycine supplements are used for reasons including supporting sleep, liver health, and skin health. Research suggests that taking glycine before bed can decrease the time to fall asleep, enhance sleep quality, and reduce daytime sleepiness. This effect may relate to glycine’s ability to lower core body temperature and its calming influence on the brain.
Dosages of glycine supplements range from 3 to 5 grams per day for adults. For improving sleep quality, 3 grams before bedtime has been shown effective in studies. Higher doses, such as 15-60 grams per day, have been explored for specific health conditions, but these are typically under professional guidance.
Glycine is well-tolerated at common doses. Mild side effects can include gastrointestinal discomfort like nausea, vomiting, or an upset stomach, especially if taken on an empty stomach or in higher doses. Drowsiness can also occur due to its inhibitory neurotransmitter activity. It is advisable to consult a healthcare professional before starting any new supplement, especially if pregnant, breastfeeding, or taking other medications. Glycine supplements are available in powder or capsule forms.