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"Last Wednesday night I gave a lecture to my clients on hunter-gatherer diets. The turnout was great and the information was well-received. I had it professionally video-recorded and will probably offer this as a DVD for sale (with the handout included). Watch for it in the future. Part of what I discussed was vitamin D3 supplementation. Since I have been supplementing with 4,000-10,000 Units of D3 per day I have noted enhanced recovery and size response from my training. Apparently, skeletal muscle has both surface receptors and nuclear receptors for D3 that augment calcium flux during contraction (from surface receptors) and have steroid-like effects at the nuclear level WRT protein synthesis. This D3 supplementation is not really "supplementation" but is instead "augmentation" to levels that would be normal if we got normal sun exposure as we did in our evolutionary past. Check out www.vitamindcouncil.org for more information. Also, check out this abstract below for your consideration. Also, check out this article."

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.

Vitamin D and skin physiology: a D-lightful story. Holick MF, Chen TC, Lu Z, Sauter E. J Bone Miner Res. 2007 Dec;22 Suppl 2:V28-33. PMID: 18290718 doi: 10.1359/jbmr.07s211 Very few foods naturally contain vitamin D, and those that do have a very variable vitamin D content. Recently it was observed that wild caught salmon had between 75% and 90% more vitamin D(3) compared with farmed salmon. The associations regarding increased risk of common deadly cancers, autoimmune diseases, infectious diseases, and cardiovascular disease with living at higher latitudes and being prone to vitamin D deficiency should alert all health care professionals about the importance of vitamin D for overall health and well being. Humans have depended on sunlight for their vitamin D requirement. The impact of season, time of day, and latitude on vitamin D synthesis is well documented.(2,3) We now report that altitude also has a dramatic influence on vitamin D3 production and that living at altitudes above 3500 m permits previtamin D3 production at a time when very little is produced at latitudes below 3400 m. It was surprising that, at 27° N in Agra (169 M), little previtamin D3 production was observed. However, there was significant air pollution that caused a haze over the city. It is likely the ozone and other UVB-absorbing pollutants in the air prevented the solar UVB photons from reaching the earth's surface to produce previtamin D3.

Vitamin D production in human skin occurs only when UV radiation exceeds a threshold. From simulations of UV irradiances, the VitD www page ( http://zardoz.nilu.no/~olaeng/fastrt/VitD.html) computes the daily duration of dermal vitamin D production at midday when UV radiation exceeds the required threshold. The daily duration depends on latitude, time, total ozone, clouds, aerosols, surface reflectivity and altitude all of which can be specified by the user

"UV-related web tools maintained by Ola Engelsen * FastRT - Fast simulations of downward UV doses, indices and irradiances at the Earth's surface: http://nadir.nilu.no/~olaeng/fastrt/fastrt.html. * VitD_quartMED - Calculated Ultraviolet Exposure Levels for a Healthy Vitamin D Status: http://nadir.nilu.no/~olaeng/fastrt/VitD_quartMED.html. * VitD - Duration of Vitamin D Synthesis in Human Skin: http://nadir.nilu.no/~olaeng/fastrt/VitD.html. "

Simulations of ultraviolet irradiances, doses and indices at the Earth's surface at user specified UV wavelengths. A simpler version for non-experts is available at http://nadir.nilu.no/~olaeng/fastrt/fastrt-ez.html

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