Age-related differences in the functional properties of lips compared with skin

Lips can easily become dry and rough and their biggest problems are drying and chapping. The cause of those problems is considered to be that the stratum corneum (SC) moisture is small and its barrier function is low. However, those problems decrease in subjects as they approach 40 years of age, after which problems due to their shape and color increase. The purpose of this study was to investigate relationships between SC properties of the lips during aging and to clarify the cause(s) of lip problems.

One hundred and 38 Japanese female subjects with normal skin ranging in age from 16 to 78 years were enrolled in the study. The capacitance and transepidermal water loss (TEWL) values, viscoelasticity, and color of their lips were measured and compared with their cheeks.

The capacitance values for the lip and the cheek increased and TEWL values for both areas decreased with age. TEWL values for the lip decreased until ~30 years of age and this is considered to be related to the problem of drying. Although the maximum amplitude U_f of the lip increased with age, the U_r /U_f had no correlation with age. As for color, the L* and a* values decreased with age.

Age-related changes with regard to SC functions, viscoelasticity and color of the lips have been clarified for the first time, and it is clear that these changes are related to problems of the lips. Compared with the cheeks, differences with the lips are more apparent.