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

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

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.

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.

Food frequency questionnaires will be filled out at the initial visit and final visit. Diet will be assessed using 3-day diet history form and Nutrition Pro analysis software. Patients will be asked to refrain from taking other Vitamin D supplements and to continue their usual calcium intake.

Inclusion Criteria:

1. Healthy White women aged 50 and older who have been postmenopausal for at least 2 year (i.e. absence of menstrual period for a period of 24 months or more).
2. Willingness to discontinue self-administration of vitamin D and calcium supplements. Participants must be at least three months off supplements before starting the study.
3. Willingness to take study medications and participate in study for one year.
4. Written informed Consent Signed.
5. Patients with hypertension and diabetes stable for last three months.

Exclusion Criteria:

1. History of hypercalciuria (24-hour urinary calcium excretion >250 mg), hypercalcemia (serum calcium >10.6), nephrolithiasis and active sarcoidosis will be excluded.
2. Serum 25-hydroxyvitamin D level >80 nmol/L or history of primary hyperparathyroidism.
3. Dietary calcium intake of >2000mg/day will be excluded
4. Use of medication that influences bone or vitamin D metabolism (e.g. anticonvulsant medications, glucocorticoids, Highly Active AntiRetroviral Therapy [AIDS treatment], antirejection medications, chronic use of steroids, high dose diuretics)
5. Treatment with Hormone replacement therapy, Selective Estrogen Receptor Modulators, Calcitonin, Parathyroid hormone , androgens, bisphosphonates, phosphate or anabolic steroids 6 months prior to the study.
6. Use of systemic steroids (oral or intravenous) within the last year at an average dose of more than 5mg/day of oral prednisone or an equivalent for a period of three months or more prior to screening.
7. Chronic medical illness including Chronic liver disease, uncontrolled diabetes mellitus; recent history of myocardial infarction or heart failure; newly diagnosed or active malignancy; uncontrolled hypertension; obesity (BMI>35 kg/m2); malabsorption, anemia, leukemia, or other hematologic abnormalities; lupus, rheumatoid arthritis, sarcoidosis, or other rheumatologic disease; chronic kidney disease, metabolic bone disease.
8. Unexplained weight loss of >15% during the previous year or history of anorexia nervosa
9. > 1 pack per day tobacco use or > 2 alcoholic beverages per day
10. Unwillingness to forego self-administration of vitamin D and calcium-containing supplements.
11. Participation in another investigational trial in the past 30 days prior to the screening evaluation
12. Significant deviation from normal in medical history, physical examination, or laboratory tests as evaluated by the primary investigator.
13. Patients with unstable hypertension or diabetes.