Glycine is an amino acid that is primarily used in anti-aging skin care products because of its ability to improve moisture retention, increase collagen production, and promote skin repair and regeneration. It can also be used as a buffering agent.
Glycine is the simplest possible amino acid with only a single hydrogen atom as its side chain. As an amino acid, glycine functions as a building block in the production of proteins. Glycine is a non-essential amino acid, which means it can be synthesized within the human body. Glycine should not be confused with another ingredient that is commonly used in skin care products called “glycine soja”, which is soybean extract.
In cosmetics and personal care products, glycine primarily functions as an anti-aging ingredient based on its ability to improve moisture retention, increase collagen production, and promote skin repair and regeneration. It can also be used as a buffering agent.
After topical application, glycine and other amino acids can effectively penetrate the skin because they have an average molecular weight of 110 Daltons. This is well under the 500 Dalton rule, which states that compounds that are above 500 Daltons have a much harder time penetrating into the skin.
One way that glycine benefits the skin is by improving moisture retention. Glycine and other amino acids are naturally present in skin as part of the Natural Moisturizing Factor (NMF). In addition to amino acids, the NMF is composed of various small compounds such as sugars and electrolytes that work to keep skin’s surface intact, supple, and hydrated. Specifically, amino acids work together with aquaporins (the body’s water transport system) to move moisture throughout skin. Therefore, topical application of amino acids like glycine helps to improve moisture retention in the skin.
Glycine is often used in anti-aging skin care products because of its ability to reduce the appearance of fine lines and wrinkles by stimulating collagen production. One of the major factors that contributes to the formation of lines and wrinkles is a decrease in the amount of collagen in the skin. The body produces less and less collagen with age. In fact, after the age of 20, a person produces about 1 percent less collagen in the skin each year. Moreover, environmental free radicals can degrade collagen proteins. The result is skin that becomes thinner and more fragile with age. Collagen has a triple helix structure composed of glycine and two other amino acids, proline and hydroxyproline. Using ingredients that stimulate collagen production, such as glycine, can help to maintain skin firmness and promote skin repair and regeneration.
Lastly, glycine can function as a buffering agent, which means it is used to establish and hold the pH level of a cosmetic formulation. In chemistry, pH stands for ‘potential hydrogen’ and it refers to the level of acidity or alkalinity in a given solution. The pH scale ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic. A pH greater than 7 is basic. Adding glycine to an acidic or alkaline solution will make it neutral.
The safety of glycine and the other alpha-amino acids has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. Due to the normal presence of glycine in the body and its use as a direct food additive approved by the FDA, the Panel focused their review on dermal irritation and sensitization data. Dermal data on products containing glycine indicated that this ingredient is not a dermal irritant or sensitizer. Thus, the Panel concluded that glycine and the other alpha amino acids were safe as used in cosmetics and personal care products.
References: Wikipedia “Glycine”, Paula’s Choice “Amino Acids for Skin”, Cosmetics Info “Glycine”