title: Cardiovascular effects of calcium supplements.
abstract: Calcium supplements reduce bone turnover and slow the rate of bone loss. However, few studies have demonstrated reduced fracture incidence with calcium supplements, and meta-analyses show only a 10% decrease in fractures, which is of borderline statistical and clinical significance. Trials in normal older women and in patients with renal impairment suggest that calcium supplements increase the risk of cardiovascular disease. To further assess their safety, we recently conducted a meta-analysis of trials of calcium supplements, and found a 27%-31% increase in risk of myocardial infarction, and a 12%-20% increase in risk of stroke. These findings are robust because they are based on pre-specified analyses of randomized, placebo-controlled trials and are consistent across the trials. Co-administration of vitamin D with calcium does not lessen these adverse effects. The increased cardiovascular risk with calcium supplements is consistent with epidemiological data relating higher circulating calcium concentrations to cardiovascular disease in normal populations. There are several possible pathophysiological mechanisms for these effects, including effects on vascular calcification, vascular cells, blood coagulation and calcium-sensing receptors. Thus, the non-skeletal risks of calcium supplements appear to outweigh any skeletal benefits, and are they appear to be unnecessary for the efficacy of other osteoporosis treatments.
authors.affiliation: Faculty of Medical and Health Sciences, University of Auckland, Auckland 1142, New Zealand. i.reid@auckland.ac.nz
authors.forename: Ian R
authors.initials: IR
authors.lastname: Reid
mesh_terms: D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism; D002136:Calcium, Dietary / Q000008:administration & dosage* / Q000009:adverse effects*; D002318:Cardiovascular Diseases / Q000209:etiology / Q000503:physiopathology; D002319:Cardiovascular System / Q000187:drug effects* / Q000378:metabolism; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D015201:Meta-Analysis as Topic; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors
chemical_list: D002136:Calcium, Dietary