I found this and maybe someone else posted but I thought I would again.

Is Vitamin D Insufficiency Associated With Peripheral Neuropathy?

CME Review Article #30

Endocrinologist. 17(6):319-325, November/December 2007.
Carlson, Amanda N. MD *; Kenny, Anne M. MD +
Abstract:
The effects of vitamin D on calcium and phosphate metabolism and bone formation are well studied. For many years, it was thought that the importance of vitamin D was confined to these roles, and the study of this hormone's activity in other tissues was neglected. In recent years, however, there has been a renewed interest among researchers in identifying other target organs for vitamin D, such as the central nervous system. Increasingly, it appears that vitamin D plays a role in nerve growth and maintenance and may have important pharmaceutical applications for treatment of neurodegenerative conditions. This review focuses on our growing understanding of the biology of vitamin D in the brain and the potential pathophysiologic and therapeutic relationships that exist between vitamin D and neuronal dysfunction.

(C) 2007 Lippincott Williams & Wilkins, Inc.