Skin becomes thinner primarily due to a loss of subcutaneous fat. The ceramide content of stratum corneum decreases with advancing age, presumably diminishing barrier function. Skin loses elasticity and tone because of changes in collagen.
Older skin usually does not contain as much hyaluronic acid as younger skin. Persons with high glutathione levels are bio-chemically young. Glutathione is a tri-peptide of glycine, cystine and glutamine. It is a major antioxidant in the body providing cell protection. Breaks in DNA strands generally accompany cell aging. This increasing instability of DNA in the cells is the aging process. UV rays and oxidative reactions cause the formation of free radicals. In turn, these inactivate or destroy phospholipids. The resulting lipid peroxides are somehow related to the number of inflammatory diseases and cancers. With age, skin cells divide more slowly and the dermis begins to thin. The elastin and collagen fibers loosen, causing depressions on the skin surface. Skin thus loses elasticity and is unable to retain moisture.