Unwanted changes in the appearance of our skin are an unavoidable part of aging. It is generally accepted that these changes are due to the effects of both intrinsic and extrinsic factors. 1 Intrinsic factors include age-related decreases in keratinocytes and fibroblasts with corresponding decreases in collagen and proteoglycan production, and increased expression of matrix metalloproteinases, which increases the production of damaging reactive oxygen species. 2 Extrinsic factors include ultraviolet radiation, smoking, and other environmental insults. These can also result in free-radical formation, mitochondrial dysfunction, and DNA damage affecting biological processes such protein synthesis. 3,4 Together, these factors cause pigmentary changes as well as structural changes to the