Do calcium supplements increase the risk of blood clots? Are changes to the official recommendations required? These questions are now being discussed by the Danish Veterinary and Food Administration and the Danish Medicines Agency, etc. after an article in the British Medical Journal (BMJ) suspected calcium supplements of increasing the risk of heart attacks.
Calcium supplements are primarily used for the prevention and treatment of osteoporosis - often in combination with vitamin D or other osteoporosis drugs. People who get adequate calcium intake from food are rarely recommended to take a calcium supplement.
The article in BMJ is based on a so-called meta-analysis, which combines the results of 15 trials. The analysis showed that the persons who took a calcium supplement had a 30 per cent higher risk of myocardial infarction (heart attack) compared to persons who took a placebo (an inactive substance, "dummy pill"). It is important to highlight that the analysis only involves calcium without the concomitant use of a vitamin D supplement.
Given that many people take a calcium supplement, the Danish Veterinary and Food Administration and the Danish Medicines Agency consider the analysis food for thought, but also point out that even though a 30 per cent increased risk sounds high, the risk of having a heart attack is already low. Also, it cannot be ruled out that the results occurred by chance, i.e. that there is no true increased risk. The analysis neither showed a statistically significant increased risk of stroke (heart attack or brain haemorrhage) nor an increased risk of dying (regardless of cause).
The Danish Veterinary and Food Administration has now requested the Danish National Food Institute to evaluate the analysis. In addition, the Danish Medicines Agency will assess whether the analysis is to have consequences for the use of osteoporosis medicines.
Most calcium supplements are sold as a food supplement subject to the provisions of the Danish Food Act, and food supplements cannot be prescription-only. Only one of the calcium-containing medicines available on the Danish market is sold over the counter, and there are no immediate plans to change this.
The Danish Medicines Agency advises persons who take a calcium supplement to discuss whether it is necessary to continue taking the supplement at the next convenient doctor's visit. Persons who have been prescribed or recommended a calcium supplement by a doctor should not stop their treatment without consulting their doctor.
For further information, please contact MSc Søren Langkilde, Danish Veterinary and Food Administration, tel. +45 3395 6143 or Chief Medical Officer Jens Heisterberg, Danish Medicines Agency, tel. +45 4488 9198.
Danish Medicines Agency, 4 August 2010