Is Calcium Obtained From Food Better for Vascular and Bone Health Than That Obtained From Supplements?

The purpose of this randomized clinical trial is to estimate the effect of dietary intake of calcium and vitamin D as compared to supplemental calcium and vitamin D on arterial stiffness and markers of vascular and bone health in postmenopausal women.

Calcium and vitamin D are essential nutrients for optimal bone health throughout life. Research has shown that postmenopausal women who consume appropriate amounts of these nutrients have better bone strength and fewer fractures than those who don't. However, researchers have recently questioned the safety of calcium and vitamin D obtained through supplements as they might increase the risk of cardiovascular events such as heart attacks and strokes.

The investigators propose to estimate the effect of dietary intake of calcium and vitamin D as compared to supplemental calcium and vitamin D on vascular and bone health in postmenopausal women.

Eligible participants will be assigned by chance (like a coin toss) to one of three groups: (1) 1200 mg of calcium from dietary sources and 1 capsule of 400 IU vitamin D supplement everyday after breakfast; (2) 450 mg of calcium from dietary sources, 3 tablets of 250 mg calcium supplement, and 1 capsule of 800 IU vitamin D supplement every day after breakfast; or (3) unrestricted calcium from dietary sources and 1 capsule of 400 IU vitamin D supplement everyday after breakfast. Participants have an equal chance of being assigned to any of these three groups.

Participants will also attend appointments at the Montreal General Hospital every 6-months where they will undergo anthropometric measurements, blood tests,non-invasive ultrasounds to measure arterial stiffness and questionnaires. The questionnaires ask about health; lifestyle habits such as physical exercise, diet, and smoking; use of medications and dietary supplements; family history of illness, and past medical diagnoses. Participants will also receive monthly phone calls from study staff to monitor for adverse events and adherence.

• Cardiovascular Diseases
• Osteoporosis

• Dietary Supplement: Calcium Citrate
• Dietary Supplement: Vitamin D3
• Other: Dietary Calcium

• Active Comparator: Calcium Supplement + Vitamin D Supplement
  • 750mg Calcium Citrate per day
  • 800 IU Vitamin D3 per day
  • 450mg Dietary Calcium per day
  Interventions:

  • Dietary Supplement: Calcium Citrate
  • Dietary Supplement: Vitamin D3
  • Other: Dietary Calcium
• Active Comparator: Dietary Calcium + Vitamin D Supplement
  • 400 IU Vitamin D3 per day
  • 1200 mg Dietary Calcium per day
  Interventions:

  • Dietary Supplement: Vitamin D3
  • Other: Dietary Calcium
• Active Comparator: Regular Diet + Vitamin D Supplement
  • 400 IU Vitamin D3 per day
  • Unrestricted Dietary Calcium
  Intervention: Dietary Supplement: Vitamin D3

Inclusion Criteria:

• Women aged 55 or more;
• 3 years since last menstrual period
• Body Mass Index between 20 and 30 kg/m2

Exclusion Criteria:

• Atrial Fibrillation
• Documented atherosclerosis
• High 10-year absolute risk of fracture (FRAX without BMD > 20%)
• Hypertension
• Hyperparathyroidism
• Urinary Tract Lithiasis
• Rheumatoid Arthritis
• Diabetes
• History of gestational diabetes, hypertension, or pre-eclampsia
• Smoked in the last 5 years
• Use of bone active agents (oral glucocorticoids, bisphosphonates, Selective estrogen-receptor modulators, denosumab, teriparatide, calcitonin, HRT [excluding vaginal preparations])in the last 3 years
• Use of calcium and vitamin D supplements (including multivitamins and calcium-containing antacids) in the last 2 months