Increase in subjective well‐being and psychological health after application of C8‐silk lipoamino acid functionalized pigments included in a foundation

Objective The aim of this study was to evaluate the effects of two foundations before (D0) and after 5 days of application (D6) on psychophysiological parameters in order to compare C8‐silk lipoamino acid functionalized pigments ( FA ) versus pure pigments ( FP ). Methods Assessment of self‐esteem, stress, mood and emotion using psychological tests and evaluation of salivary cortisol concentrations were realized on 40 healthy females using a crossover study design at D0 and D6. Four saliva samples were taken on the awakening (C1), 30 min after the awakening (during the foundation application (C2)), 1 h after the foundation application (C3) and at 1900 h (C4) at DO and D6. Area under the curve was calculated in order to obtain information about the total amount of a given substance excreted in a specific time period. Results Five days of daily application of the foundation containing the pigments treated with the C8‐silk lipoamino acids induced a significant increase ( P  <   0.001) in self‐esteem and pleasant emotion ( P  <   0.05), and a significant decrease in general stress ( P  <   0.05). This was not the case after the FP application. Cortisol concentrations presented a pronounced diurnal rhythm whatever the foundation used. At DO , no significant differences were observed between the groups. At D6, cortisol concentrations measured 30 min and 1 h after the FA application were significantly lower ( P  <   0.05: C6.2, P  <   0.05 C6.3, respectively) than those reported after FP application. AUC , a global stress response indicator, was significantly lower in FA group as compared to FP group after 5 days of application. Subjects found a decrease in tiredness signs and thought that FA has a good coverage. Conclusion Our results show that incorporation of C8‐silk lipoamino acid as agent of pigment functionalization brings new benefits to a foundation. Adopting a psychophysiological approach, which is not invasive to the subjects, we show the measurement of cortisol at the same time that psychological indicators provide a scientific approach to examine the beneficial effects of a cosmetic product.