Feasibility of a clinical trial to assess the effect of dietary calciumv.supplemental calcium on vascular and bone markers in healthy postmenopausal women

13 healthy postmenopausal women aged 55 years and older (≥3 years since last menstrual period) without any chronic disease, recruited in Montreal, Quebec, Canada. Mean age 63.2, BMI 24.6. Exclusions: lactose intolerance, smoked within last 5 years, BMI <20 or >30 kg/m2, history of diabetes, pre-eclampsia, hypertension, atrial fibrillation, atherosclerosis, recent HRT use, medications affecting bone metabolism, or 10-year absolute risk of major osteoporotic fractures >20%.

Calcium supplement group (CaSuppl): 750 mg calcium carbonate supplement + 450 mg calcium from food sources + vitamin D supplement 20 µg (800 IU) daily for 12 months.

Calcium diet group (CaDiet): 1200 mg of calcium from food sources + vitamin D supplement 10 µg (400 IU) daily for 12 months.

Feasibility measures: participant adherence to the trial protocol, compliance to trial interventions (mean total Ca intake ±20% of target and use of Ca supplements ≥80%), and tolerability of Ca and vitamin D supplementation.