What is your opinion please on very low weight hyaluronic acid (hydrolyzed sodium hyaluronate — molecular weight 10kDa) contained in some hyaluronic acid products? There is some research that associates very low weight hyaluronic acid with inflammation and scarring. Also, I would be grateful for any recommendations you may have for a hyaluronic acid products for use after at-home dermarolling. -N
Dear N,
Hyaluronic acid (HA) is both naturally found in the body and used many popular skincare and beauty products (but it might be most famous for that one Eva Longoria commercial for [easyazon_link identifier=”B008EKY8VK” locale=”US” tag=”cosmeticswiki-20″]L’Oreal Revitalift[/easyazon_link]!) Hyaluronic acid resides in both the epidermis and the deeper dermis, where it plays a key role in hydration, skin repair, and protection against free radicals and UV damage. It is able to bind moisture in up to 1,000 times its own weight when topically applied to the skin (Skin Pharmacology and Physiology, 2004) and also helps the skin heal after injury (American Journal of Clinical Dermatology, 2005; Biologicals, 2011).
However, skincare fanatics have been criticizing hyaluronic acid because of its large size. The 500 Dalton rule states that molecules larger than that cannot penetrate the skin; therefore, the quite large 1-1.5 million Dalton hyaluronic acid isn’t penetrating the skin at all. Instead, it binds to water atop the skin, forming a gel. It may still have proven effects in studies as far as hydrating and preventing water loss go, but it’s not plumping the skin from within.
Enter the SLMW (super low-molecular-weight) form, which is just 10,000 Daltons. (It should be mentioned Ultra Low Molecular Weight (ULMW) Hyaluronic Acid is also available, at less than 6,000 Daltons (6 kDa)).
Any low molecular weight hyaluronic acid is made by enzymatically cleaving high-molecular-weight hyaluronic acid into small fragments. These smaller fragments can no longer form a gel with water like the large molecules, but they can theoretically penetrate the skin much easier and actually have a better anti-irritant and regenerating effect once absorbed by the skin. The high molecular form of HA has a better hydrating effect than the low-molecular form of HA.
Because they are theoretically able to penetrate the skin easier, they are being marketed as a more effective version of hyaluronic acid and popping up in more and more products.
Why I Like Low Molecular Weight Hyaluronic Acid
While even the lowest molecular weight hyaluronic acid will not penetrate the skin (6,000 Daltons is a lot more than 500 Daltons!), they do produce hydrating and plumping effects that are superior to that of higher molecular weight HA. An in vitro study found that LMW HA (110 kDA – 300 kDA) improves wound injury, whereas HMW HA (1,000 – 1,400 kDa) and SLMW HA (5 – 20 kDa) had no healing effects (21).
I theorize this is because you’re covering a greater surface area more thoroughly. For instance, if you’re painting a roof, you’ll typically use more paint if you use small strokes of paint, rather than single large brush strokes. Each small stroke of hyaluronic acid means your skin is collectively binding more water and forming more gel with HA.
But yes, as you mentioned, there have been studies conducted that show “macrophages exposed to low molecular weight HAs are encouraged to produce pro-inflammatory mediators associated with the classically activated state.” Macrophages are associated with the inflammatory or healing response in the skin. For this reason, I would NOT use low molecular weight HA on skin that is sun damaged, abraded, open, etc. Otherwise, I personally think it is fine.
What are your thoughts on hyaluronic acid? Let me know in comments below!