Guidelines on selection of products with Hyaluronic Acid
Hyaluronic acid is well-known for its ability of water-binding to keep the skin supple and hydrated. The less-known part is its benefits such as anti-aging, anti-wrinkle, better skin elasticity, etc. Thus, it is still a popular item despite being in market for a long time. Here is a guidance on how to select hyaluronic acid products from many available in the market!
What does hyaluronic acid do?
Naturally synthesized within the skin, hyaluronic acid is sugar molecule that is found extensively between cells within the epidermis and dermis. The major function of hyaluronic acid is hydration as it can bind water many folds to keep skin ample, supple and hydrated.
Hyaluronic acid in cosmetic:
In most cosmetic products, sodium hyaluronate is used instead of hyaluronic acid. Sodium hyaluronate is the sodium salt of hyaluronic acid. It functions the same way as hyaluronic acid but has lower molecular weight and better penetration for quick, deep-down delivery and superior efficacy. In the following discussion, we collectively call hyaluronic acid and sodium hyaluronate as “HA”.
Size does matter but skin age is also a consideration
Some skincare brands emphasize “low molecular weight HA” in their products. Some are said to contain a combination of HA with different molecular weight. Apparently, these claims are related to their properties of penetration into the skin. The question then arises: Does the skin benefit more from smaller HA?
Some facts you need to know:
1. The purpose of topical application of HA is mainly to hydrate epidermis. As there is lipid-rich layer within the epidermis that blocks HA from passing through, topical HA will not be able to reach the dermis.
2. HA with different molecular weight (“MW”) serves different function.
High MW HA stays mostly on top of the skin to form a moisturized protective film to reduce trans-epidermal water loss (“TEWL”). Its function is to give an immediate suppleness to the skin.
Smaller MW HA can be readily absorbed into the deeper layer within the epidermis to boost moisture and have anti-wrinkle effects. HA with size of 130kDa (the unit of MW) has been found to be the most effective in increasing elasticity. According to a study*, it can increase skin elasticity by 20% in a month.
As young and healthy skins don’t face anti-aging issues, these will only need high MW HA. However, a mature and dry skin will need blend of HAs with different MW for benefit of long-lasting moisture and anti-aging effects.
HA is generally safe for everybody as our skin naturally produces it. However, at high concentration, it can be irritating or drying instead of hydrating. Some dermatologists suggest that 2% is the maximum but typical input rate for cosmetic is 0.1-0.5% w/w.
What we have learned about selecting hyaluronic acid?
1. HA is beneficial to almost every skin type, including sensitive skins.
2. Young and normal skin types can use high MW HA to protect the skin from TEWL and to improve the roughness of the skin.
3. Mature and dry skin will benefit from the combination of high and low MW HA.
4. High concentration of HA may cause irritation or dryness.