Clinical Trial: Study the Effects of Vitamin D and Calcium Supplementation at Tolerable Upper Limit Doses on Calcium Metabolism.

Study Status: Completed
Recruit Status: Completed
Study Type: Interventional

Official Title: The Effects of Vitamin D and Calcium Supplementation at Tolerable Upper Limit Doses on Calcium Metabolism in Postmenopausal White Women.

Brief Summary: Recently two distinguished committees, Institute of Medicine (IOM) and The Endocrine Society have proposed different intake guidelines for Calcium and Vitamin D. We wish to compare the effects of both of them on calcium metabolism and bone turnover. We propose a one year randomized double blinded study for the same.

Detailed Summary:

The specific aims of this study proposal are to determine the following:

1. To compare the two different intake guidelines for Calcium and Vitamin D Supplementation at its recommended tolerable upper limit on serum and urinary calcium in white postmenopausal Women.
2. Compare the effects above mentioned two intake guidelines on Vitamin D metabolism [25(OH)D, 1,25(OH)2D] and bone turnover.

Participants will be randomly assigned to Group A or Group B based on different dosages of study medications.

Group A: 10,000 IU (International Units)Vitamin D + Placebo (sugar pill) 600IU Vitamin D + Two pills Calcium containing 600mg calcium each.

Group B: 600 IU Vitamin D + Placebo (sugar pill) 10,000 IU Vitamin D

+ Two pills Calcium containing 600mg calcium each.

In addition to the calcium supplements, they will guide to include approximately 800mg of calcium in their daily diet.

At visit 2, fasting blood and spot urine will be collected. A urinal will be dispensed for collection of 24-hour urine for urinary calcium to be brought in next day. Study medication will be dispensed and participants will be asked not to discard unused medications and to bring all study medications next study visit.

Visit 3, 4, 5, 6 will essentially be the same as visit 2, with subjects returning unused study medication and given new tablets each visit. Except on visit 6 no further study medications will be dispensed, after collecting the previous supply.

Endocrine society has recommended tolerable upper limit or a dose with no adverse events as 10,000IU of Vitamin D and 2000 mg/day of calcium. Our study will test the safety/ efficacy of this recommendation.