Aging decreases the capacity of human skin to produce vitamin D3.

Abstract

An evaluation of surgically obtained skin (age range, 8-92 yr) revealed that there is an age-dependent decrease in the epidermal concentrations of provitamin D3 (7-dehydrocholesterol). To ascertain that aging indeed decreased the capacity of human skin to produce vitamin D3, some of the skin samples were exposed to ultraviolet radiation and the content of previtamin D3 was determined in the epidermis and dermis. The epidermis in the young and older subjects was the major site for the formation of previtamin D3, accounting for >80% of the total previtamin D3 that was produced in the skin. A comparison of the amount of previtamin D3 produced in the skin from the 8-and 18-yr-old subjects with the amount produced in the skin from the 77-and 82-yr-old subjects revealed that aging can decrease by greater than twofold the capacity of the skin to produce previtamin D3. Recognition of this difference may be extremely important for the elderly, who infrequently expose a small area of skin to sunlight and who depend on this exposure for their vitamin D nutritional needs.

Prevalence and predictors of vitamin D insufficiency in women of reproductive age living in northern latitude

“…In contrast to many studies, we found no association between age and serum 25OHD, which could be accounted for the young age of our population. Indeed, a greater than twofold decline in epidermal stores of 7-dehydrocholesterol, the skin precursor of vitamin D 3 , was demonstrated when elderly people aged 77 and 88 years were compared with individuals aged 8 and 18 years old (30). Contrary to what we anticipated, sunscreen use and sunlight exposure were not associated with serum 25OHD levels.…”

Conversion of 7-Dehydrocholesterol to 7-Ketocholesterol Is Catalyzed by Human Cytochrome P450 7A1 and Occurs by Direct Oxidation without an Epoxide Intermediate

“…One is the fate of 7-dehydrocholesterol, the immediate precursor of cholesterol. 7-Dehydrocholesterol is observed at very low levels or is not normally detectable in tissues and fluids of humans except in skin (3)(4)(5), where it is converted to previtamin D 3 under UV irradiation (6). Thus, 7-dehydrocholesterol is important aside from its reduction to cholesterol.…”

All sites but skin cancer incidences analyzed worldwide by sex, age, and skin type over time (1955-2007), advancing age, and UVB dose reveals important carcinogenic drivers

“…[55] We know low levels of vitamin D 3 fuel persistent HPV infection [79] that has been steadily increasing over recent decades in developed countries in Europe [53] and in the US. [7] Moreover, all cancer incidences probably increase over the advancing age of the individual because their ability to make vitamin D 3 decreases with increasing age due to thinning of the epidermis [80] and exposure to higher ROS levels, as shown by the shutdown of melanin synthesis in hair turning it white. [81] Decreasing vitamin D 3 levels and increasing ROS with advancing age along with male estrogen levels that are 2-3 times higher than females over the age of 49 might explain why all cancer incidences increase with increasing age and steadily increase with advancing age of males (see Figures 3A and 3B and values in Table 3).…”