Calcium intake and bone mineral density: systematic review and meta-analysisBMJ 2015; 351 doi: https://doi.org/10.1136/bmj.h4183 (Published 29 September 2015) Cite this as: BMJ 2015;351:h4183
- Vicky Tai, medical student1,
- William Leung, health economist2,
- Andrew Grey, associate professor of medicine1,
- Ian R Reid, professor of medicine1,
- Mark J Bolland, associate professor of medicine1
- 1Department of Medicine, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- 2Department of Public Health, University of Otago, PO Box 7343, Wellington 6242, New Zealand
- Correspondence to: M Bolland
- Accepted 29 July 2015
Objective To determine whether increasing calcium intake from dietary sources affects bone mineral density (BMD) and, if so, whether the effects are similar to those of calcium supplements.
Design Random effects meta-analysis of randomised controlled trials.
Data sources Ovid Medline, Embase, Pubmed, and references from relevant systematic reviews. Initial searches were undertaken in July 2013 and updated in September 2014.
Eligibility criteria for selecting studies Randomised controlled trials of dietary sources of calcium or calcium supplements (with or without vitamin D) in participants aged over 50 with BMD at the lumbar spine, total hip, femoral neck, total body, or forearm as an outcome.
Results We identified 59 eligible randomised controlled trials: 15 studied dietary sources of calcium (n=1533) and 51 studied calcium supplements (n=12 257). Increasing calcium intake from dietary sources increased BMD by 0.6-1.0% at the total hip and total body at one year and by 0.7-1.8% at these sites and the lumbar spine and femoral neck at two years. There was no effect on BMD in the forearm. Calcium supplements increased BMD by 0.7-1.8% at all five skeletal sites at one, two, and over two and a half years, but the size of the increase in BMD at later time points was similar to the increase at one year. Increases in BMD were similar in trials of dietary sources of calcium and calcium supplements (except at the forearm), in trials of calcium monotherapy versus co-administered calcium and vitamin D, in trials with calcium doses of ≥1000 versus <1000 mg/day and ≤500 versus >500 mg/day, and in trials where the baseline dietary calcium intake was <800 versus ≥800 mg/day.
Conclusions Increasing calcium intake from dietary sources or by taking calcium supplements produces small non-progressive increases in BMD, which are unlikely to lead to a clinically significant reduction in risk of fracture.
Contributors: MJB, WL, VT, AG, and IRR designed the research. WL and MJB performed the literature searches. VT and MB extracted or checked data. MJB performed the analyses. MJB and VT drafted the paper. All authors critically reviewed and improved it. MJB is guarantor. All authors had access to all the data and take responsibility for the integrity of the data and the accuracy of the data analysis.
Funding: This study was funded by the Health Research Council (HRC) of New Zealand. The authors are independent of the HRC. The HRC had no role in study design, the collection, analysis, and interpretation of data, the writing of the article, or the decision to submit it for publication.
Competing interests: All authors have completed the ICMJE uniform disclosure form at http://www.icmje.org/coi_disclosure.pdf and declare: MJB is the recipient of a Sir Charles Hercus health research fellowship; IRR has received research grants and honorariums from Merck, Amgen, Lilly, and Novartis.
Ethical approval: Not required.
Transparency statement: MB affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned have been explained.
Data sharing: No additional data available.
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