Hyaluronic acid (HA) is a molecule that occurs naturally in human skin and as we age it slowly decreases. HA is a hydrophobic or water-holding substance and it's benefits for building and retaining moisture in skin are well understood. Maintaining HA levels helps the skin hold moisture and reduce dryness and applying HA as a topical serum is an effective way to help moisturise skin. Older skin benefits more than young skin from HA application. HA cannot stop the clock and prevent ageing but it will help reduce the tendency for skin to become drier with age.
Hyaluronic acid is also an example of the way in which rapid progress in biotechnology has helped high quality natural products become more readily available. A few decades ago the main source of HA was from animals and this always sat a little uneasily with the concept of natural, ethical beauty. However, progress in biotechnology and biofermentation now means that HA can be produced naturally by bacteria rather than extracted from animal tissue. The quality has also improved and the results are much better.
Time is behind ageing of course and it's consequences - and time also underpins progress in our knowledge and understanding of the natural world - or wisdom ?