title: Increased skin pigment reduces the capacity of skin to synthesise vitamin D3.
abstract: To determine the effect of increased skin pigment on the cutaneous production of vitamin D3, circulating vitamin D concentrations were determined in two lightly pigmented Caucasian and three heavily pigmented Negro volunteers after exposure to a single standard dose of ultraviolet radiation (UVR). Exposure of Caucasian subjects to 1 minimal erythemal dose of UVR greatly increased serum vitamin-D concentrations by up to 60-fold 24-48 h after exposure, whereas this dose did not significantly change serum vitamin-D concentrations in Negro subjects. Re-exposure of one Negro subject to a dose of UVR six times larger than the standard dose increased circulating vitamin D to concentrations similar to those recorded in Caucasian subjects after exposure to the lower dose. These results indicate that increased skin pigment can greatly reduce the UVR-mediated synthesis of vitamin D.
mesh_terms: D044383:Black People; D002762:Cholecalciferol / Q000096:biosynthesis*; D006801:Humans; D008543:Melanins / Q000378:metabolism; D011829:Radiation Dosage; D012279:Rickets / Q000517:prevention & control; D012867:Skin / Q000378:metabolism*; D012880:Skin Pigmentation / Q000528:radiation effects*; D014466:Ultraviolet Rays; D014467:Ultraviolet Therapy; D014807:Vitamin D / Q000097:blood; D044465:White People
chemical_list: D008543:Melanins; D014807:Vitamin D; D002762:Cholecalciferol