Many of us swallow vitamin supplement pills each day, including calcium for bone health. Clinical guidelines on osteoporosis recommend supplementation with calcium especially for those who are at high risk for bone loss and fractures.
But the truth is, the benefits of calcium supplements are rather unclear, not to mention contradictory. Previous studies have shown that:
- Calcium can protect against vascular disease.
- Calcium can cause vascular disease by hastening vascular calcification.
So what now?
A group of researchers at the University of Auckland in New Zealand conducted a systematic search of electronic databases and conducted a meta-analysis of randomized clinical trials of calcium supplements compared to placebo. The results of the meta-analysis might have answered the calcium supplement question once and for all and can be summarized below:
- Calcium supplements were associated with a significant increase (about 30%) in incidence of heart attacks.
- Calcium supplements were also associated with trend of increased risk of stroke and mortality, although the increase is much smaller and not statistically significant.
These findings were consistent in all 5 trials included in the analysis and the increase of MI risk due to the supplements also increased with higher dietary calcium intake. Age, gender and type of supplement did not influence the results.
What is even more disappointing is the finding that calcium supplements have very little benefits when it comes to preventing fractures.
How reliable are the current results?
Some experts speculate that misdiagnosis of heart burns caused by the supplements as cardiac chest pains may have given erroneous results. This is based on the fact that many of the heart attack reported occurred within an average of 3.6 years after calcium supplementation was started. However, calcification of the blood vessels should take longer than that.
In addition, the studies analyzed were only those that did not include vitamin supplementation. It is common clinical practice, however, that calcium and vitamin D supplements are coadministered for osteoporosis. It is not clear whether vitamin D, which supposedly has cardiovascular protective properties, combined with calcium would give the same results.
However, the majority of experts agree is the fact that calcium supplements do not seem to prevent fracture indicates it is practically useless to take them even if the supplements as such are safe and do not cause heart problems.
According to senior author Dr Ian R Reid:
According to independent expert Dr John Schindler (University of Pittsburgh Medical Center in Pennsylvania:
“I think the safest thing to tell your patients right now is if you can get your dietary calcium from good dietary sources, such as yogurt, sardines, and skim milk, that potentially might be all you need to ward off the risk of osteoporosis. Then we don’t have to deal with this increased cardiovascular risk.”