Protective properties of Avene Thermal Spring Water on biomechanical, ultrastructural and clinical parameters of human skin

Background Thermal Spring Water (TSW) has been recognized to have beneficial effects on skin; however, the mechanisms underlying these are not completely elucidated. Aims We compared the effects of Avene TSW with mineral-rich (MR) TSW on the biomechanical properties of the skin using mechanisticex vivoassays and clinical studies. Methods Ex vivostudies included the effect of both TSWs on the structure of the surface of human skin explants using scanning electron microscopy (SEM); mineral elemental content on the skin surface using SEM coupled to energy dispersing X-ray spectroscopy; and the stress properties of the stratum corneum (SC) when exposed to dehydration. Human clinical studies were conducted to compare the soothing effect of TSWs after a dermatological chemical peeling of face skin and to evaluate the overall sensitive scale of consumers using Avene TSW for 7 days. Results Both TSWs preserved surface skin ultrastructure; however, crystals formed from MR-TSW were needle-like and formed small grains, present in clusters heterogeneously spread over the surface. Needle crystals were mainly composed of calcium, while small clusters were mainly composed of sulphur. By contrast, Avene TSW-formed crystals composed of sodium and chlorine only were regular in shape and homogeneously distributed across the skin surface. Peak stress of SC layers was increased by MR-TSW, whereas Avene TSW showed a comparatively reduced effect on dehydration and stress. The difference in the two TSW types was reflected in clinical findings comparing postpeeling redness after TSW application. Avene TSW significantly decreased postpeeling redness, while MR-TSW increased it. The overall sensitive scale of consumers was decreased by 47% using Avene TSW for 7 days. Conclusions Avene TSW decreases postpeeling redness and soothes sensitive skin in human volunteers. Mechanistic studies suggested that differences in biomechanical effects could be linked to differences in calcium content of the TSW.