Studies on Vitamin D have discovered some amazing things such as:
Individuals with MS tend to have insufficient Vitamin D Levels.
Taking vitamin D supplements (it has to be supplements, most people in northern climates do not get enough sun exposure) for more than 10 years lowered the risk of developing MS by 59%1.
Low vitamin D status could be associated with higher mortality from life-threatening conditions including cancer, cardiovascular disease, and diabetes mellitus that account for 60% to 70% of total mortality in high-income countries.” 
Vitamin D supplements are associated with decreases in total mortality rates.2
High circulating levels of vitamin D are associated with a lower risk of multiple sclerosis.
You can obtain a vitamin D test from your primary care physician.Vitamin D supplementation in infancy seems to exert a strong protective effect against the autoimmune disease type 1 diabetes, and vitamin D levels in early childhood could also have an impact on the risk of MS.”3
It has been known for more than a century that sunlight can treat tuberculosis. Treating tuberculosis with sunshine was so effective that its discoverer was awarded the Nobel Prize in 1903. 
Approximately 220,149 new cases of breast cancer and 254,105 new cases of colorectal cancer would be prevented annually in the world by raising serum vitamin D3 concentrations to approximately 40 to 60 ng/mL, which is, in general, associated with oral intake of 2,000 IU of vitamin D3 per day.
Vitamin D is a power house supplement and one that is extremely inexpensive. We carry a Vitamin D in our office that each capsule is 2,000 IU’s. With 250 capsules one bottle will last 8 ½ months and only cost $10.00.
 “Vitamin D Intake and Incidence of Multiple Sclerosis” NEUROLOGY, January 13, 2004;62:60-65
 Vitamin D Supplementation and Total Mortality” Archives of Internal Medicine, September 10, 2007; 167:1730-173
 “Serum 25-Hydroxyvitamin D Levels and Risk of Multiple Sclerosis”, Journal of the American Medical Association December 20, 2006 pp. 2832-2838
 Fight Infections with Vitamin D, Nature Medicine, April 2006, 12(4):388-390
 Vitamin D for Cancer Prevention: