Calcium supplements linked to coronary artery calcification

Taking calcium supplements in an effort to prevent or treat osteoporosis may increase the risk for developing coronary artery calcification a new study has found.

The observational study, conducted by researchers from the division of Cardiology at Johns Hopkins University in the US, is the latest strike against calcium in a decade-long debate about whether the supplements do more harm than good.

Researchers compared baseline dietary and supplement intake of 2,742 participants as well as their CT scans taken at the start of the study and again at follow up 10 years later.

Among participants with a baseline CAC of zero the highest calcium intake (≥1453 mg) compared to the lowest intake (<434 mg) was associated with a 27% decreased risk for incident CAC, suggesting a protective effect of total calcium intake in the highest consumers of overall calcium.

But when they looked at supplement use, the risk of developing incident CAC was 22% higher in those who used supplements than those who did not.

Medical director of Osteoporosis Australia, Professor Peter Ebeling said there has been an overemphasis on the benefits of calcium supplements.

“I think it does need to be redressed and I certainly think there’s an overemphasis of the benefits of calcium and vitamin D in reducing fractures,” he told the limbic.

He said supplements were probably most effective in the institutionalised elderly who are largely vitamin D deficient but for an ambulatory population there was less convincing evidence that calcium supplements were effective.

“Nevertheless we know for optimal bone health we need an adequate intake of calcium and we would definitely recommend increasing intake through dietary means and not using supplements where that can be avoided” he said.

Endocrinologist and Associate Professor at Auckland University’s School of Medicine, Mark Bolland, has researched the role of calcium supplements in bone health extensively and published systematic reviews and meta analyses concluding that the risks associated with taking calcium supplements outweigh any small benefit gained.

“At an individual level most people are not going to benefit from taking calcium supplements,” he told the limbic in an interview.

“If you’ve got a 20% risk of having a fracture in the next five years and if you take a calcium supplement for those five years that will reduce your chance of having a fracture by 2%.”

Professor Bolland said his research confirmed that calcium and vitamin D were ineffective in treating or preventing osteoporosis, and that taking calcium increased the risk of heart attacks in older people by as much as 30% and slightly less than that for increasing risk of stroke.

According to Dr Bolland, in each of the major large trials that examine the role of calcium supplements in primary prevention of fracture, more people were admitted to hospital for treatment of other effects linked to supplement use than the number fractures prevented.

Since publishing his team’s findings in the BMJ last year, Professor Bolland says there has been a 70% drop in calcium supplement use in New Zealand and it’s use is no longer recommend in NZ guidelines.

“Regardless of the side effect issue, if you put that aside, the evidence of benefit for calcium is fairly weak and I think when we talk to patients about that they actually aren’t interested in taking it.”

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