The Role of Lipids in the Process of Hair Ageing

Abstract

An obvious sign of ageing is the loss of hair colour due to a decrease or lack of melanin in hair fibres. An examination of the lipid levels and structure of grey hair determined using µ–FTIR revealed a high correlation between the characteristics of lipids located in the cuticle and the water dynamics of the fibres. Therefore, a deep study based on external and internal lipid extraction, an analysis using thin layer chromatography coupled to an automated flame ionisation detector, calorimetric analyses and the physico-chemical evaluation of the delipidated fibres were performed. Hairs were evaluated to identify changes in the organisation of these lipids using Fourier transform infrared spectroscopy and their effect on the water dynamics of the fibres. The primary differences observed for the lipid extracts from white hair compared to brown hair were the lower amount of the internal lipids extracted, which were primarily composed of free fatty acids (FFAs) and ceramides, with a higher content of lower phase transition peaks, indicating increased unsaturated compounds that promote higher fluidity of the lipid bilayers. The virgin white fibres exhibited lower levels of embedded water, with lower binding energies and higher water diffusion, indicating higher permeability. The IR study confirmed the low lipid levels and the greater disorder of white hair. These results may be of interest for cosmetic treatments to which patients with grey hair may be subjected.