Calcium Supplements - Boon or Bane?
Emphasis has always been laid on meeting the calcium recommendations. Time and again it is reiterated that milk and milk products are a great source of calcium and it is essential to make sure that they are judiciously consumed. Calcium and vitamin D supplements are a must to prevent and treat osteoporosis. It is seen as a mandatory measure in preserving bone density and reducing fracture risk.
But recent studies are raising concerns on the indiscriminate use of calcium supplements.
Prior studies have already inferred a possible relationship between calcium supplementation and cardiovascular disease risk. This makes us rethink whether the risks due to calcium supplement consumption outweigh the benefits they offer.
Bolland and colleagues specifically examined the relationship of calcium with risk of heart attacks and cardiovascular events and published the findings in the British Medical Journal. Analyses of data identified a significant increase in heart attacks in those randomized to calcium supplements. The study concluded that the relative risk of myocardial infarction increased by about 30 percent.
However, the study excluded vitamin D, as opposed to treatment guidelines and common recommendations. Due to the above mentioned and other drawbacks the analysis was redone by Bolland et al in April 2011.
Bolland et al used the Women's Health Initiative (WHI) dataset to establish the risk of cardiovascular events due to calcium supplement consumption with or without vitamin D.
Data of 16,718 women who were not taking personal calcium supplements at the start of the trial was analysed. It was found that those subjects who combined calcium and vitamin D supplements were at an increased risk of cardiovascular events, especially heart attack.
In contrast to women who were taking personal calcium supplements at the start of the trial, the supplementation did not alter their cardiovascular risk.
The possible reason behind this could be a sudden change in blood calcium levels after supplementation rather than being related to the total amount of calcium consumed. High blood calcium levels are linked to calcification (hardening) of the arteries, which may lead to myocardial infarction and heart attack.
There is insufficient evidence available to support or refute the association. Because of study limitations the findings that calcium supplements given with vitamin D do not cause adverse cardiovascular events or their association with increased cardiovascular risk are not at all assured. Further studies need to be done.
With the uncertainty regarding the findings one needs to be cautious about consuming calcium supplements. But it's a fact that foods such as milk and milk products, green leafy vegetables, millets, and seeds are rich natural sources of calcium. No harm has ever been shown from calcium consumption via these dietary sources. Calcium supplements still remain important for those with low dietary intakes, or those at risk of or being treated for osteoporosis. Always consult your doctor before consuming any calcium and vitamin D supplements.
1.Bolland MJ et al "Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis" BMJ (Clinical research ed.), 2010, 341.
2. Bolland, MJ et al "Calcium supplements with or without vitamin D and risk of cardiovascular events: reanalysis of the Women's Health Initiative limited access dataset and meta-analysis" BMJ, April2011, 342.