Does Omeprazole Decrease Intestinal Calcium Absorption?

Inclusion Criteria: * Women at least 5 years past menopause, defined as the last date of menses Exclusion Criteria: * Allergy/Intolerance to orange juice * Allergy/Intolerance to omeprazole or other PPI therapy * Use of drugs that interact with omeprazole including oral anti-fungal agents, coumadin, diazepam, phenytoin \& tacrolimus * Use of antacids, PPI or H2-blocker therapy within the past two months * Intestinal conditions associated with malabsorption or low gastric acid levels including Crohn's Disease, ulcerative colitis, pernicious anemia, bacterial overgrowth, celiac sprue, chronic diarrhea or use of antibiotics within the past month * Known Stage 4 or 5 Chronic Kidney Disease, defined as an estimated GFR \<30 cc/minute * Use of medications known to interfere with calcium metabolism, including oral steroids or anticonvulsants