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Daily duration of vitamin D synthesis in human skin with relation to latitude, total ozone, altitude, ground cover, aerosols and cloud thickness. Engelsen O, Brustad M, Aksnes L, Lund E. Photochem Photobiol. 2005 Nov-Dec;81(6):1287-90. PMID: 16354110 Vitamin D production in human skin occurs only when incident UV radiation exceeds a certain threshold. From simulations of UV irradiances worldwide and throughout the year, we have studied the dependency of the extent and duration of cutaneous vitamin D production in terms of latitude, time, total ozone, clouds, aerosols, surface reflectivity and altitude. For clear atmospheric conditions, no cutaneous vitamin D production occurs at 51 degrees latitude and higher during some periods of the year. At 70 degrees latitude, vitamin D synthesis can be absent for 5 months. Clouds, aerosols and thick ozone events reduce the duration of vitamin D synthesis considerably, and can suppress vitamin D synthesis completely even at the equator. A web page allowing the computation of the duration of cutaneous vitamin D production worldwide throughout the year, for various atmospheric and surface conditions, is available on the Internet at http://zardoz.nilu.no/~olaeng/fastrt/VitD.html and http://zardoz.nilu.no/~olaeng/fastrt/VitD-ez.html. The computational methodology is outlined here.

An acknowledged benefit of exposure to ultraviolet radiation is synthesis of vitamin D in human skin. Here we have defined a standard vitamin D dose based upon recommended requirements for vitamin D, and present a web-based tool that enables the user to calculate associated exposure times for any time and place ( http://nadir.nilu.no/~olaeng/fastrt/VitD_quartMED.html). The recommended UV exposure times depends on latitude, time, total ozone, clouds, aerosols, surface reflectivity and altitude all of which can be specified by the user. A simpler version for non-experts is available at http://nadir.nilu.no/~olaeng/fastrt/VitD-ez_quartMED.html

Vitamin D replacement in Asians with diabetes may increase insulin resistance. Taylor AV, Wise PH. Postgrad Med J. 1998 Jun;74(872):365-6. PMID: 9799895 We report three cases of vitamin D replacement in British Asians with vitamin D deficiency and non-insulin-dependent diabetes mellitus. In all cases, replacement resulted in an increase in insulin resistance and a deterioration of glycaemic control

"Vitamin D facts are not well known - even though this fat soluble vitamin is essential to our good health. As more and more Vitamin D facts are being discovered in Vitamin D research, this vitamin is being found to be IMPERATIVE to our good health in many different ways."