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Vitamin D: An Evolving Star

By: Peter T. Pugliese, MD
Posted: June 29, 2009, from the July 2009 issue of Skin Inc. magazine.
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page 10 of 11

18. Dietary Supplement Fact Sheet: Vitamin D, National Institute of Health


a The UV index is a scale with higher values representing the risk level of skin damage due to UV exposure. A value of 0 corresponds to zero UV irradiation, such as occurs during nighttime. An index of 10 corresponds roughly to midday sun and a clear sky. The numbers are related to the amount of UV radiation reaching the surface of the Earth, measured in watts per square meter of surface.

b Dendritic cells (DC) are immune cells that form part of the mammalian immune system. Their main function is to process antigen material and present it on the surface to other cells of the immune system, thus functioning as antigen-presenting cells. DCs are present in small quantities in tissues that are in contact with the external environment, mainly the skin (where there is a specialized DC type called Langerhans cells) and the inner lining of the nose, lungs, stomach and intestines.

c One IU equals 25 nanograms.

d Paracrine means a type of cell stimulation that is initiated by other cells close by, as opposed to endocrine stimulation that occurs from afar.