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Evidence Summary
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Key messages from scientific research that's ready to be acted on
Got It, Hide thisIn people over 50 years of age, dietary or supplemental calcium increases bone mineral density
Tai V, Leung W, Grey A, et al. Calcium intake and bone mineral density: systematic review and meta-analysis. BMJ. 2015 Sep 29;351:h4183.
Review question
In people over 50 years of age, does increasing calcium in the diet or with supplements affect bone mineral density (BMD)? See related Evidence Summary of a review by Bolland.
Background
Calcium is important for bone health, but people often don’t get enough of it in the food they eat. As we age, we lose bone mass. Doctors often recommend eating more calcium-rich foods or taking calcium supplements to improve bone mass, which is measured as BMD.
How the review was done
The researchers did a systematic review, including studies up to September 2014. They found 15 randomized controlled trials of dietary calcium that included 1533 people and 51 randomized controlled trials of calcium supplements that included 12 257 people.
Dietary sources of calcium were milk or milk powder, dairy products, or hydroxyapatite (a supplement that is made from bone and has other minerals, hormones, protein, and amino acids in addition to calcium).
The main results were BMD at the lumbar spine (lower back), femoral neck (top part of the thigh bone that connects to the ball of the hip joint), total hip, and forearm.
What the researchers found
21 trials had a low risk of bias.
Dietary calcium increased BMD by 0.7% to 1.8% at lumbar spine, femoral neck, and total hip at 2 years.
Calcium supplementation increased BMD by 1.0% to 1.8% after 2.5 years.
The reviewers did not assess whether people taking additional calcium had fewer bone problems such as fractures.
Conclusion
In people over 50 years of age, dietary calcium or calcium supplements increase bone mineral density by less than 1.8%.
Dietary calcium or calcium supplements in people over 50 years of age
| Bone mineral density (BMD) measurement site | Source of calcium | Number of trials (number of people) | Effect of calcium on BMD |
| Lumbar spine | Diet | 8 trials (816 people) | Increased BMD by 0.7% at 2 years |
| Femoral neck | Diet | 7 trials (783 people) | Increased BMD by 1.8% at 2 years |
| Total hip | Diet | 5 trials (689 people) | Increased BMD by 1.5% at 2 years |
| Forearm | Diet | 2 trials (171 people) | No difference in effect at 2 years |
| Lumbar spine | Supplements | 8 trials (3,861 people) | Increased BMD by 1.0% after 2.5 years |
| Femoral neck | Supplements | 5 trials (2,257 people) | Increased BMD by 1.5% after 2.5 years |
| Total hip | Supplements | 6 trials (3,835 people) | Increased BMD by 1.2% after 2.5 years |
| Forearm | Supplements | 5 trials (437 people) | Increased BMD by 1.8% after more than 2.5 years |
Glossary
Studies where people are assigned to one of the treatments purely by chance.
Possibility of some systematic error in the studies.
A comprehensive evaluation of the available research evidence on a particular topic.
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