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Calcium supplementation for improving bone density in lactating women: a systematic review and meta-analysis of randomized controlled trials

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journal contribution
posted on 2023-05-20, 15:00 authored by Guoqi CaiGuoqi Cai, Jing TianJing Tian, Tania WinzenbergTania Winzenberg, Feitong WuFeitong Wu
Background: Clinical trials evaluating the effect of calcium supplementation on bone loss in lactating women have been small, with inconsistent results.

Objectives: We aimed to determine the effect of calcium supplementation on bone mineral density (BMD) in lactating women.

Methods: An electronic search of databases was conducted from inception to January 2020. Two authors screened studies, extracted data, and assessed the risk of bias of eligible studies. Percentage change in BMD was pooled using random-effects models and reported as weighted mean differences (WMDs) with 95% CIs. Risk of bias was assessed using the Cochrane risk of bias tool.

Results: Five randomized controlled trials including 567 lactating women were included. All had a high risk of bias. Mean baseline calcium intake ranged from 562 to 1333 mg/d. Compared with control groups (placebo/no intervention), calcium supplementation (600/1000 mg/d) had no significant effect on BMD at the lumbar spine (WMD: 0.74%; 95% CI: -0.10%, 1.59%; I2 = 47%; 95% CI: 0%, 81%; n = 527 from 5 trials) or the forearm (WMD: 0.53%; 95% CI: -0.35%, 1.42%; I2 = 55%; 95% CI: 0%, 85%; n = 415 from 4 trials). BMD at other sites was assessed in single trials: calcium supplementation had a small to moderate effect on total-hip BMD (WMD: 3.3%; 95% CI: 1.5%, 5.1%) but no effect on total body or femoral neck BMD.

Conclusions: Overall, the meta-analysis indicates that calcium supplementation does not provide clinically important benefits for BMD in lactating women. However, there was adequate dietary intake before supplementation in some studies, and others did not measure baseline calcium intake. Advising lactating women to meet the current recommended calcium intakes (with supplementation if dietary intake is low) is warranted unless new high-certainty evidence to the contrary from robust clinical trials becomes available. More research needs to be done in larger samples of women from diverse ethnic and racial groups.


Publication title

American Journal of Clinical Nutrition








Menzies Institute for Medical Research


Amer Soc Clinical Nutrition

Place of publication

9650 Rockville Pike, Subscriptions, Rm L-3300, Bethesda, USA, Md, 20814-3998

Rights statement

Copyright © The Author(s) on behalf of the American Society for Nutrition 2020.

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  • Restricted

Socio-economic Objectives

Clinical health not elsewhere classified

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