Hyaluronic acid is one of the superstar ingredients in the realm of skincare. And it’s no wonder--it plumps up, hydrates, and rejuvenates the skin, helping us slow down the changes that come with ageing and skin damage.
While hyaluronic acid has been around for decades, scientists are still uncovering its secrets in the hopes of improving its effectiveness. One particularly interesting area of research is the difference between hyaluronic acid molecules of different molecular weights. Several studies have found that these differences impact the characteristics and biological activity of hyaluronic acid.
Research is still ongoing, but these new findings could lead to big changes in the way this amazing ingredient is being used.
The function of hyaluronic acid in the skin
When people think of hyaluronic acid, what comes to mind is its benefits as a skincare ingredient. But the hyaluronic acid in our bodies affects much more than the outer appearance of our skin.
This molecule serves as an important component of the matrix surrounding the skin cells in the epidermal layer, working as a cushion against pressure and damage, as well as allowing the passage of nutrients from the blood to the skin cells suspended in it.
However, hyaluronic acid is not just an inert structural component of the body--it also participates in biological activities. Here, there has been a clear difference when comparing molecules of varying molecular weights.
High molecular weight (HMW) hyaluronic acid appears to play a role in wound healing and repair, immunomodulation, and inhibition of blood vessel formation. Due to its size, its texture is thicker and more viscous--this is likely why joint fluid contains mostly HMW hyaluronic acid. Its cushioning effect is needed in areas that are exposed to friction and impact.
On the other hand, low molecular weight (LMW) hyaluronic acid exhibits the opposite effect by promoting inflammation and angiogenesis. The fibroblasts in our skin produce hyaluronic acid of varying molecular weights, but the triggers to increase or decrease production are still being studied.
Hyaluronic acid as a skin ingredient
Hyaluronic acid is touted as one of the best humectants in the skincare market today. The key to this property lies in its molecular structure. It is arranged in such a way that the hydrophobic portions are surrounded by the hydrophilic portions. In aqueous solution and physiological pH, water is attracted to these hydrophilic groups.
However, how deeply hyaluronic acid in topical preparations penetrates the skin is influenced by its molecular weight. The longer the chain, the heavier and bigger the molecule. As a consequence of its size, HMW hyaluronic acid cannot penetrate the skin as easily as its LMW counterpart.
It may sound like that’s a bad thing, but having a product that has hyaluronic acid molecules of varying molecular weights could be the future of skincare.
The presence of HMW hyaluronic acid on the surface of the skin provides a thin, invisible coating to keep water from going out. It pulls water from the deeper layers of the skin into the surface, revitalizing the outer appearance. Meanwhile, LMW hyaluronic acid is able to enter the deeper layers of the epidermis, where it helps boost collagen production. It can settle in between cells, offering a subtle plumping effect.
Hyaluronic acid as a dermal filler
If you want to up your hyaluronic acid game, you may want to check out hyaluronic acid implants. This procedure involves the injection of hyaluronic acid into the dermis, where it can help fill out laugh lines, wrinkles, acne scars, and other shallow textural irregularities. Because hyaluronic acid is naturally produced by our bodies, using it as a filler rarely causes an allergic reaction.
Studies on the effect of molecular weight on hyaluronic acid’s effectiveness as a dermal filler are continuously being produced, but early results show that HMW forms are more promising. These larger molecules have increased viscosity, which makes them better space fillers.
While this procedure is safe and well-tolerated, it is important to have it done at a dermatology clinic. A consultation with the doctor will help you figure out if it’s the best procedure for your particular skin issue and help manage expectations. Hyaluronic acid fillers are not permanent and require sessions to keep up the appearance.
Conclusion
Hyaluronic acid has been used as a skin ingredient for decades, and yet there is still so much we don’t know about it. Researchers are continuously making new discoveries that could widen its applications and change the way it is used.
This content is for general information only and is not a substitute for medical advice.
Resources:
Mazzucco, Antonio. (2019). Hyaluronic Acid: Evaluation of Efficacy with Different Molecular Weights. International Journal of Chemistry and Research. 1. 13-18. 10.18689/ijcr-1000103.
Chun, C., Lee, D. Y., Kim, J. T., Kwon, M. K., Kim, Y. Z., & Kim, S. S. (2016). Effect of molecular weight of hyaluronic acid (HA) on viscoelasticity and particle texturing feel of HA dermal biphasic fillers. Biomaterials research, 20(1), 24. https://doi.org/10.1186/s40824-016-0073-3
The biological effects of hyaluronic acid depend heavily on molecular weight. Hyaluronic acid with molecular weights from 0.4 to 4.0 kDa acts as an inducer of heat shock proteins, and has a non-apoptotic property. Polysaccharides with a molecular weight equal to 6–20 kDa possess immunostimulatory, angiogenic, and phlogotic activities. Hyaluronic acid with a molecular weight of 20–200 kDa takes part in biological processes such as embryonic development, wound healing and ovulation. By contrast, high molecular weight hyaluronic acid (>500 kDa) has anti-angiogenic activity, and can function as a space filler and a natural immunologic depressant
