Effect of aging on sebaceous gland activity and on the fatty acid composition of wax esters.

Using fused-silica capillary gas chromatography, we investigated sebum samples from 55 healthy individuals to discover the effects of aging on the sebaceous gland activity and on the fatty acid composition of wax exters. The sebaceous gland activity, which was expressed by the ratio of wax esters/[cholesterol + cholesterol esters] (WE/[C + CE]), showed a distinct change from infancy through maturity to senescence; the curve of the ratio made a peak in our subjects's 20s. Using the fatty acid analyses, we found an interesting relationship between C16:1 straight and C16:1 iso-branched chains, each of which occupied a large proportion in the fatty acids of wax esters; the former increased in proportion from infancy toward the 20s, with a correlation with aging (r = 0.788, p less than 0.01), and decreased thereafter until our subject's 50s (r = -0.611, p less than 0.01). In contrast, the proportion of the latter followed an entirely reversed course with advancing age. The percentages of C16:1 straight chain components were correlated positively with the WE/[C + CE] ratio (r = 0.642, p less than 0.01), while there was found to be a negative correlation between the proportion of C16:1 iso-branched chain components and the WE/[C + CE] ratio (r = -0.556, p less than 0.01). The results suggest that more active sebaceous glands in lipid production excrete lipids with a higher proportion of C16:1 straight chain fatty acid and a lower proportion of C16:1 iso-branched chain fatty acid. As well as the sebaceous gland activity, the fatty acid composition in sebum wax esters is affected by advancing age in Japanese.