Hyaluronic acid (HA) is an ingredient that’s enjoying a lot of buzz in the skin care industry, and for good reason. The benefits of HA are impressive, and it is now a key ingredient of many creams, serums, injectables and even supplements. Consider the key benefits and efficacy of hyaluronic acid as a topical ingredient.
CHEMISTRY IN COSMETIC APPLICATION
Hyaluronic acid is a substance that occurs naturally in the body that helps hydrate the skin. This natural glycosaminoglycan is distributed widely throughout connective, neural and epithelial tissue. It is one of the chief components of the extracellular matrix, the tissue that provides structural support to cells (and hence to skin). The average individual has a molecular weight of about 15 grams of hyaluronic acid in the body with a turnover of about five grams every day. In humans, it is most abundant in the skin, which accounts for 50 percent of the body’s total hyaluronic acid.
HA synthesis increases during tissue injury and wound healing. It regulates several aspects of tissue repair, including activation of inflammatory cells to enhance immune response and the increased response to injury of fibroblasts and epithelial cells.
Hyaluronic acid is enjoying widespread use in the cosmetic industry for its function as an excellent topical moisturizer and anti-inflammatory agent. It is available in a number of molecular weights for skin care formulators and manufacturers to select the desired level of function and performance of the finished product. This is marketed to estheticians and consumers as low, mid and high molecular weight hyaluronic acid.
High molecular weights help bind moisture at the surface of the skin and act as hydrating humectants. Mid-molecular weights can help “plump” the skin, while low molecular weights can enhance the penetration of other cosmetic ingredients. Smaller molecular weights may also allow deeper penetration into the skin and help restore the aging dermis.
Youthful skin retains its turgor, resilience and pliability, among other traits, due in large part to its high water content. Over time, loss of moisture occurs as part of the normal process of aging, in addition to daily external injury. HA is a key molecule involved in skin moisture due to its unique capacity in retaining water. It is a strong hydrophilic or “water loving” compound. It binds with a large volume of water, giving solutions high viscosity, even at low concentrations. In fact, HA is capable of holding up to 1,000 times its molecular weight in water, penetrating the skin and binding skin cells to water, infusing all layers of the skin with moisture.
Wounded skin must be repaired. HA plays an important role in the various stages of inflammation and is believed to play a multi-faceted role in the mediation of many cellular matrix processes. In the process of inflammation, hyaluronic acid promotes an increase in pro-inflammatory cytokines at very low concentrations. HA is unique in that it not only promotes inflammation, it can also moderate the inflammatory response, in turn contributing to the stabilization of the healing matrix. HA can also function as a free radical scavenger, which further aids in wound healing.
HA has a very important role in the physiology of the normal epidermis and is crucial to the process of skin repair. It is usually found in high concentrations in the basal layer of the epidermis. This area maintains an open, well-hydrated structure that allows the passage of nutrients, one of its main functions. It is also known to increase the presence of retinoic acid. Although not fully understood, it is believed that the mechanism is related to photo damage and the aging process.
Beyond the anti-aging benefits of superior hydration, hyaluronic acid is widely used in the treatment of wrinkles and sagging skin to help restructure the dermis. It is generally used alone or modified to reduce the action acid of hyaluronidase, the enzyme that breaks down hyaluronic acid. There are many HA products on the market used by cosmetic surgeons for skin injections to treat wrinkles.
Frequently, hyaluronic acid products are combined with vitamin A and/or peptides as an anti-aging formula. Recent studies have shown it to be incompatible with certain forms of vitamin C, as it tends to break down the molecule. The level of relative humidity in the environment can affect the level of efficacy and performance. Dry climates can cause products with high concentrations of HA to accelerate TEWL in the skin.
Learn how you can make the most of the hyaluronic acid in your treatment room in our June edition!
Don’t miss Michael’s lecture on the science and benefits of hyaluronic acid at the main stage for the International Congress of Esthetics and Spa, Philadelphia on May 21-22!