Vitamin D and Disease
This page once provided links to talks by several prominent vitamin D researchers. Those links no longer work, unfortunately. However, using a search engine, one can easily investigate the many linkages between various health conditions and a vitamin D3 deficiency that have been discovered over the past decade or so, and I encourage you to do so to convince yourself of the importance of maintaining your personal D3 levels.
On the next page, Vitamin D and Dyslexia, I explain why I believe a link between dyslexia and a vitamin D3 deficiency could exist.