BMJ calcium-heart study not valid for dietary calcium, Marigot

20-Sep-2010 - Last updated on 21-Sep-2010 at 10:46 GMT

Dietary calcium occurs in combination with traces of other minerals that have a positive synergistic effect – unlike synthetic calcium used in many supplements, says Marigot, which says the results of a recent meta-analysis balancing bone benefits against heart risk do not hold for the dietary form.

The meta-analysis published in the British Medical Journal (BMJ) last month looked at the data on 12,000 people involved in 15 trials published in the last 20 years which looked at calcium supplementation, bone fractures and heart attack risk.

The researchers concluded that taking calcium supplements can increase the risk of heart attack by 30 per cent, and deemed that the risks to outweigh the benefits.

But David O’Leary, commercial manager at Irish ingredient firm Marigot, says people should not presume the findings apply to all sources of calcium. Not only is vitamin D understood to boost absorption of calcium, but O’Leary also drew attention to research indicating that presence of trace minerals copper, selenium and zinc can positively enhance bone density.

His company’s Aquamin calcium ingredient can be used in supplement capsules but comes from seaweed and has a complex mineral make up – 75 in total, in addition to calcium and magnesium. This means it is considered to be ‘dietary calcium’ by many nutritionalists..

“Given that no study has found that high intake of food stuffs containing calcium can lead to an increased cardiovascular risk, this is an important distinction to make in the context of the recent study. On this basis alone, the use of a dietary source of calcium, such as Aquamin, would clearly make a difference to the overall findings.”

He added that the study actively excluded trials where calcium was administered in dietary form or as a complex nutritional supplement.

“This means that the bone health benefits of calcium were not fully explored and so calls into question the claim that the risk to cardiovascular health outweighs any positive effects.”

In an interview with NutraIngredients.com, study leader Professor Ian Reid did acknowledge the difference between synthetic and dietary calcium, saying: “People assume that these supplements are natural. A high calcium meal is natural, but taking highly concentrated calcium tablets is not, and does not have the same effects.”

The Health Supplement Information Service also responded to the research findings. “While the results of this meta-analysis are interesting and should encourage more research, the authors did not include the totality of the evidence on calcium supplementation and there were limitations to the analysis. For these reasons, it is not appropriate at this stage to change public health advice on the use of calcium supplements to maintain bone health."

The Danish Veterinary and Food Administration (DVFA) and the Danish Medicines Agency (DMA) have said they would analyse the study findings along with calcium use in Denmark.

At the same time, however, they played down the meta-analysis’ significance.

"Calcium supplements are primarily used for the prevention and treatment of osteoporosis - often in combination with vitamin D or other osteoporosis drugs," said the DMA. "It is important to highlight that the analysis only involves calcium without the concomitant use of a vitamin D supplement."