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

Abstract

The aim of this study was to evaluate the effects of two foundations before (D0) and after 5days of application (D6) on psychophysiological parameters in order to compare C8-silk lipoamino acid functionalized pigments (FA) versus pure pigments (FP). 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), 30min after the awakening (during the foundation application (C2)), 1h after the foundation application (C3) and at 1900h (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. 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 30min and 1h 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 5days of application. Subjects found a decrease in tiredness signs and thought that FA has a good coverage. 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.