Steve Gibson, from GRC.com, did some serious study into vitamin D. I'm a long time fan and follow his weekly podcast on internet security titled Security Now. I've linked to his web page of vitamin D information and show a couple videos about deficiencies typical in computer geeks. Staying out of the sunlight, staring into a computer monitor all day is one sure way to come up short on the vitamin D these studies say is important to your health.

To GRC.com and Vitamin D information