Conflicts of Interest
APC
W.M., M.W., and C.D. are engaged by MEDENA AG in research and development of hair care products. MEDENA AG kindly covered the APC for the paper. None of these coauthors influenced the decision to publish the article, to design the study, to interpret the data, and to write the paper. However, they participated in the development of product compositions, studied their stability, and registered them as cosmetics. The other authors declare no conflict of interest.