title: Changes in structure and geometric properties of human hair by aging.
abstract: To clarify hair changes by aging, the effect of age on hair properties was investigated from macro- to microscopic view points. Sensory hair luster tests were performed on 230 Japanese females from 10 to 70 years of age, revealing that hair luster decreases with age. The age dependence of the hair diameter and the ellipticity of the hair cross section could not explain luster reduction by aging. It has been determined that an irregular increase in fiber curvature occurs with age and is a cause of luster reduction with aging. A detailed structural analysis by synchrotron radiation microbeam X-ray diffraction revealed that the inhomogeneity in the lateral distribution of the hair microstructure increased with age and relates to the irregular increase in curvature. Such an increase in curvature is one of the important factors that leads to a poor alignment of hairs and luster reduction, and is related to the appearance of aging hair.
authors.affiliation: Beauty Research Center, Kao Corporation, 2-1-3 Bunka, Sumida-ku, Tokyo 131-8501, Japan.
authors.forename: Shinobu
authors.initials: S
authors.lastname: Nagase
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Kajiura
authors.forename: Akira
authors.initials: A
authors.lastname: Mamada
authors.forename: Hiroko
authors.initials: H
authors.lastname: Abe
authors.forename: Satoshi
authors.initials: S
authors.lastname: Shibuichi
authors.forename: Naoki
authors.initials: N
authors.lastname: Satoh
authors.forename: Takashi
authors.initials: T
authors.lastname: Itou
authors.forename: Yuya
authors.initials: Y
authors.lastname: Shinohara
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Amemiya
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D002648:Child; D005260:Female; D006197:Hair / Q000502:physiology* / Q000648:ultrastructure; D006801:Humans; D008875:Middle Aged; D013499:Surface Properties; D014961:X-Ray Diffraction; D055815:Young Adult