4.1. Study Medication (Vitamin D/Placebo): Vitamin D is well tolerated and often used in clinical practice. It is freely available as an over the counter supplement. There are few side effects to oral vitamin D, with the most severe being hypercalcemia with prolonged use of a high dose. Vitamin D toxicity can occur when the active form is given (1,25 dihydroxyvitamin D) or with prolonged exposure to high dose vitamin D3. Both young and old adults have taken one time high dose vitamin D3 safely. It is possible that an allergic reaction could occur to the medication and participants will be asked to report and symptoms.