JOURNAL OF COSMETIC SCIENCE 66 Pappas et al. (13) explored the possible variation of lipid production and composition based on ethnicities and concluded that composition, particularly wax esters, and lipid output may be affected by ethnicity however, they did not limit the study to a particular age group. Focusing on a very specifi c age group, as was done in this research, allowed a less variable comparison since age also affects skin lipid composition (15). Additionally, wax esters play a role in barrier function and hydration (21), so understanding the com- plex relationship between each of the SSL components could also provide insight into the maintenance of healthy skin. It is known that diet is a contributing factor in lipid metabolism in skin (22). The high variation of squalene among the subjects in this study, particularly with the unique lipid distribution from vegans and vegetarians, while not signifi cant in number, could poten- tially be explained by the mechanism of squalene and triglyceride synthesis on a glandu- lar level. It has been shown that acetate directs lipogenesis toward the production of squalene at the expense of triglycerides (23). Similarly, triglyceride synthesis is heavily infl uenced by the amount of glycogen available to the sebaceous glands (24). A diet low in fat could contribute to this observation however, more research is needed to prove these mechanisms are signifi cant from a dietary standpoint. When an SSL mimetic of young, healthy skin is applied topically to the skin, it can im- part many of the benefi ts attributed to the skin’s natural SSLs. The mimetic provided better short-term barrier recovery than other botanicals with skin-lipid-like attributes and did not negatively impact long-term barrier maintenance, as was seen with an oc- clusive ingredient like petrolatum. Similarly, the SSL mimetic provided short- and long- term hydration and limited regression upon discontinuation of product use. It also increased viscoelasticity and hydration in aged skin, demonstrating the importance of replenishing SSLs on skin that has lower quantities due to age. Figure 4. Evaluation of skin hydration, elasticity, and fi rmness after 1 week of test article use.

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