# Unveiling the Role of Minerals and Trace Elements of Thermal Waters in Skin Health
## 3 Conclusions and Future Perspectives  
Thermal spring waters have been shown to be effective in several dermatologic diseases and skin conditions, exerting anti-inflammatory activities in atopic dermatitis, pos  
\begin{table}
\begin{tabular}{c c c} \hline
**TSW** & **Main Composition** & **Beneficial Effects** \\ \hline \multicolumn{3}{c}{} & \multicolumn{2}{c}{Soothing properties} \\ \multicolumn{3}{c}{} & \multicolumn{2}{c}{Protection against dehydration} \\ \multicolumn{3}{c}{} & \multicolumn{2}{c}{Hemat  
riasis, seborrhea, seborrheic dermatitis, and ichthyosis, among others, and they can also improve wound healing. Other skin conditions such as rosacea and acne benefit from TSW, and, in addition to the anti-inflammatory effects, skin barrier recovery is an important part of topical treatment with TSW, both by spraying and by applying cosmetics made from them. It is considered that the synergy between minerals/compounds (chemical effects) and the mechanical, thermal, and immunological effects are responsible for the actions on the human body and, specifically, on the skin, where minerals and trace elements play a crucial role.  
In this review, studying each anion and cation separately, it has been proven that the main anions involved in the actions of TSW on the skin are chloride, which exerts anti-inflammatory and immunomodulatory actions and also maintains skin hydration; sulfate, which also has anti-inflammatory properties as well as antioxidant and antibiofilm activity (and can prevent the formation and growth of complex microbial communities); bicarbonate, which exerts anti-irritant, anti-inflammatory, and antioxidant activities as well as having soothing properties, protecting against dehydration, and also promoting skin regeneration; and carbonate, which enhances the wound healing process. Among the cations, calcium and sodium can improve wound healing, and magnesium improves skin barrier function, increases skin hydration, and reduces inflammation. Trace elements have also been found to exert several activities; selenium is characterized by its antioxidant properties, and strontium seems to have similar properties; manganese and boron promote wound closure; and zinc has been shown to reduce pruritus after a photodynamic therapy procedure. Other compounds found in TSW are considered to be involved in skin care, such as SiO\({}_{2}\), which has been shown to have anti-inflammatory activity and participate in skin barrier recovery; sulfur and its derivatives (SH\({}^{-}\); H\({}_{2}\)S), which has been demonstrated to improve wound healing and psoriasis; and CO\({}_{2}\)-rich waters, which are able to improve blood flow.  
This evidence can support the chemical action of TSWs, but more research is needed to elucidate the exact mechanism of action of each specific thermal spring water.  
M.L.M.: Conceptualization, methodology, investigation, writing--original draft preparation, writing--review and editing. C.P.G.: methodology, investigation, writing--review, and editing. J.L.L.: Writing--review and editing, supervision. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
No new data were created or analyzed in this study.  
The authors declare no conflicts of interest.  
References