The Effect of Vitamin D Statues on Endothelial Function

Inclusion criteria

• Healthy, community-dwelling ambulatory post-menopausal women.
• Able and willing to sign informed consent.
• Ages: 55-65.
• Baseline serum 25OHD concentration > 10 ng/ml and < 60 ng/ml
• Not pregnant
• Willing to avoid use of cod-liver oil and non-study vitamin D supplementation; standard multiple vitamins containing ≤ 400 IU used no more than once daily will be allowed.
• Willing to utilize sunscreen of SPF-15 or higher when sun exposure for more than 15 minutes is expected.
• Willing to fast for 12 hours.

Exclusion criteria

• Current hypercalcemia (serum calcium > 10.5 mg/dl) or untreated primary hyperparathyroidism.
• History of nephrolithiasis
• Baseline 24-hour urine calcium > 250 mg
• Known risk factors for hypercalcemia, e.g., malignancy, tuberculosis, sarcoidosis, Paget's disease.
• History of any form of cancer within the past five years with the exception of adequately treated squamous cell or basal cell skin carcinoma.
• Known previous personal history of cardiovascular disease.
• Renal failure; defined as a calculated creatinine clearance (using the Cockroft-Gault approach) of ≤ 25 ml/minute.
• Severe end-organ disease, e.g., cardiovascular, hepatic, hematologic, pulmonary, etc., which might limit the ability to complete this study.
• Treatment with any drug known to interfere with vitamin D metabolism, e.g., phenytoin, phenobarbital.
• Known malabsorption syndromes, e.g., celiac disease, active inflammatory bowel disease, etc.
• Known allergy to chocolate.
• Use of medications known to alter bone turnover including bisphosphonates, estrogen, selective estrogen receptor modulators, parathyroid hormone, testosterone or calcitonin.
• Treatment with any active metabolites of vitamin D, e.g., calcitriol, within six months of screening.
• Use of tanning beds or salons or unwillingness to utilize sunscreen during periods of sun exposure of 15 minutes or longer.