The Effects of Aging on Hair–More Than Just Amount 476 cells. We have not been able to locate a comprehensive study of hair lipid composition versus age on a large number of subjects however, there is literature that allows us to connect the dots and arrive at a few useful conclusions. Nicolaides and Rothman51 determined that the cholesterol content of the hair fat of boys 6–12 years of age (females were not included in the study) is much higher than that of adults, while the squalene content for this same group is only a fraction of that of adults. In another paper, Nicolaides and Rothman52 showed that the total free fatty acid content of the hair of young Caucasian boys (ages 6–12) is lower than that of pooled hair of adults. These effects may be attributed to the fact that the amount of lipids from the sebaceous glands that are incorporated into the hair fiber are lower before puberty and the sebaceous glands’ contributions are higher after puberty. In support of this conclusion, upon reaching puberty the sebaceous gland activity increases dramatically. The increased sebaceous output increases the amount of squalene, fatty acids, and wax esters in teenagers and adults hair compared with the hair of children.51-53 Furthermore, Pochi et al.54 found that the ratio of wax esters (sebaceous origin) to cholesterol and cholesterol esters (matrix cell origin) increased from 0.35 in children to 7.47 in young adult women and then decreased to 1.46 in post-menopausal women. Pochi and Strauss determined sebum content from the foreheads of males and females at different ages (see Figure 2).53-55 These same scientists also concluded that the amount of sebum produced varies with the size of the sebaceous gland. The data of Pochi and Strauss shows that sebum is very low before puberty, but increases rapidly at puberty and remains at a high level until about age 45–50 where it declines, and the decline with females is greater than the decline for males. Interestingly, data for lipids on and in hair by age, derived from unpublished data by the P&G/Wella Hair Research Group, shows a corresponding relationship to that found on foreheads (see Figure 3). In this study, hair samples were collected from 51 Caucasian females varying in age 7–88 years, extracted and analyzed by GC/ MS, at the German Wool Research Institute DWI, for lipids. The