Randomized Controlled Trial of Calcium Supplementation in Healthy, Nonosteoporotic, Older Men

Abstract

Background: There is no consistent evidence, to our knowledge, that calcium supplementation affects bone mineral density (BMD) in men, despite male osteoporosis being a common clinical problem.Methods: To determine the effects of calcium supplementation (600 mg/d, 1200 mg/d, or placebo) on BMD in men, we conducted a double-blind, randomized controlled trial for a 2-year period at an academic clinical research center. A total of 323 healthy men at least 40 years old (mean age, 57 years) were recruited by newspaper advertisement. Complete follow-up was achieved in 96% of subjects. Results:The BMD increased at all sites in the group receiving calcium, 1200 mg/d, by 1% to 1.5% more than those receiving placebo. The results for the group receiving calcium, 600 mg/d, were not different from the placebo group at any BMD site. There was no interaction between the BMD treatment effect and either age or dietary calcium intake.

Relationships between vascular calcification, calcium metabolism, bone density, and fractures

“…The study design and results of both trials have been published previously. (10,14,15) The women were over 55 years of age, were not taking agents for osteoporosis (including hormone-replacement therapy or vitamin D supplements in doses > 1000 IU/day), and were free from major ongoing illnesses, including hepatic, renal, or thyroid dysfunction, malignancy, metabolic bone disease, or serum 25-hydroxyvitamin D concentration of less than 25 nmol/L and had normal spine BMD for their age (Z-score > -2). The men were over 40 years of age, free from major ongoing illness (including coronary heart disease, hypertension, diabetes, renal or thyroid dysfunction, liver disease, malignancy, or metabolic bone disease), had an estimated 5-year cardiovascular risk of greater than 15% and a serum 25-hydroxyvitamin D concentration of less than 25 nmol/L, had normal spine and hip BMD for their age (Z-score > -2), and were not using lipid-lowering therapy or agents that might have an impact on calcium metabolism.…”

“…Dietary calcium was assessed using a validated questionnaire, (39) and laboratory measurements were carried out as described previously. (14,15) …”

“…Missing scores were due to scans not being undertaken (0 baseline, 18 follow-up) or scan quality (3 baseline, 7 follow-up). The baseline characteristics of the cohorts have been published previously, (10,14,15) and selected variables are shown in Table 1. The mean duration of follow-up of the women was 4.4 years and of the men was 2.0 years.…”

“…(11) The mechanism of the association between calcium metabolism and vascular disease is unknown. The process of vascular calcification is thought to be similar to bone formation, (12,13) and since calcium supplements increase bone mineral density (BMD), (14,15) they also may increase vascular calcification.…”

“…(36,37) We have recently completed randomized, controlled trials of calcium supplements in a cohort of healthy elderly women and a cohort of healthy middle-aged or older men. (14,15) We set out to investigate whether indices of calcium metabolism, dietary calcium intake, or use of calcium supplements were associated with AAC or CAC in these trials. We also investigated whether there was any association between AAC and BMD or fractures or between CAC and BMD.…”