HA of different molecular weights penetrate the skin at different depths, and influence the inflammatory cascade at different points. The claim that low molecular weight HA penetrates the deepest and is therefore the most beneficial is essentially a marketing gimmick. For example, high molecular weight HA that does not penetrate the skin at all remains on the surface of skin, forming a protective barrier, and keeping the skin’s surface hydrated. Therefore, the ideal HA product contains a combination of HAs of different molecular weights, each selected for optimum benefit at the layer where it acts.
Dr. Felix Li
18 April 2019