Glycerin inclusion levels for skin hydration: a data-driven approach
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Presented by: Thibaud Richard
Introduction:
Skin hydration claims have been around for many decades and are still one of the most sought after benefit from cosmetic products. There are several strategies to deliver such benefit, with a myriad of formulation available on the market. Glycerin, a by-product of soap manufacturing, is among recurring ingredients with a long history of use for skin hydration. Easiness to formulate and affordability makes it an attractive option , yet it may come at the expense of a tacky feeling in formulation when used in high quantities. We thus aimed at retrospectively analyse the minimum levels of glycerin required in certains formulation types that allow to deliver a significant skin hydration effect, measured in clinical settings using the corneometeter.
Methods:
Retrospective corneometer data of 134 products were compiled. Formulation types consisted of emulsions (e.g. creams, lotions, foundations) watery gels or solutions (e.g. toners). These data encompasses skin hydration at baseline and at 2, 8 and 24 hours following a single application of a product. Product were evaluated on the forearms with mixed panels of men and women. The whole dataset was investigated using descriptive statistics and bootstrapped 95% confidence intervals (CI) were calculated.. A linear mixed effect models (LMM) was used to estimate the magnitude of skin hydration increase according to the glycerin content.
Results:
When corrected to an untreated site, similar level of glycerin were found to be sufficient to elicit a significant skin hydration at 2 and 8 hours, while higher quantities were required for a 24 hour sustained effect, as per corneometer measurements. Estimates of expected skin hydration were computed with LMM although the variance explained by the model suggest that explanatory power of the model deserved to be improved, in particular for estimates at 24 hours.
Discussion and Conclusion:
Probing relevant levels of glycerin to achieve skin hydration in clinical settings can help addressing several objectives : gain confidence on expected performance, reduce reliance on prototypes screening but more importantly, inclusion of a sensible amount of glycerin to mitigate detrimental effects on sensorial attributes.
Skin hydration claims have been around for many decades and are still one of the most sought after benefit from cosmetic products. There are several strategies to deliver such benefit, with a myriad of formulation available on the market. Glycerin, a by-product of soap manufacturing, is among recurring ingredients with a long history of use for skin hydration. Easiness to formulate and affordability makes it an attractive option , yet it may come at the expense of a tacky feeling in formulation when used in high quantities. We thus aimed at retrospectively analyse the minimum levels of glycerin required in certains formulation types that allow to deliver a significant skin hydration effect, measured in clinical settings using the corneometeter.
Methods:
Retrospective corneometer data of 134 products were compiled. Formulation types consisted of emulsions (e.g. creams, lotions, foundations) watery gels or solutions (e.g. toners). These data encompasses skin hydration at baseline and at 2, 8 and 24 hours following a single application of a product. Product were evaluated on the forearms with mixed panels of men and women. The whole dataset was investigated using descriptive statistics and bootstrapped 95% confidence intervals (CI) were calculated.. A linear mixed effect models (LMM) was used to estimate the magnitude of skin hydration increase according to the glycerin content.
Results:
When corrected to an untreated site, similar level of glycerin were found to be sufficient to elicit a significant skin hydration at 2 and 8 hours, while higher quantities were required for a 24 hour sustained effect, as per corneometer measurements. Estimates of expected skin hydration were computed with LMM although the variance explained by the model suggest that explanatory power of the model deserved to be improved, in particular for estimates at 24 hours.
Discussion and Conclusion:
Probing relevant levels of glycerin to achieve skin hydration in clinical settings can help addressing several objectives : gain confidence on expected performance, reduce reliance on prototypes screening but more importantly, inclusion of a sensible amount of glycerin to mitigate detrimental effects on sensorial attributes.