The use of calcium supplements without co-administered vitamin D is associated with an increased risk of MI

Most guidelines for the prevention or treatment of osteoporosis recommend the use of calcium supplements, despite the fact that they reduce the risk of fracture only marginally

Studies have yielded conflicting results about their use, with some observational studies suggesting that high calcium intake is protective against vascular disease, and others showing that calcium supplements speed vascular calcification and increase mortality in patients with kidney failure and increase cardiovascular events and MI in women.

In a combined analysis of the five studies that had contributed patient-level data, the investigators found that calcium supplements were associated with about a 30% increase in the incidence of MI and smaller, non-significant increases in the risk of stroke and mortality.

The findings were consistent across trials, and the risk of MI with calcium supplements tended to be greater in those with higher dietary calcium intake. The MI risk was independent of age, sex, and type of supplement.

Clinicians should tell their patients that, for most older people, the risks of calcium supplements outweigh the benefits. Changing to calcium-rich foods may be appropriate.

Calcium Supplements Causing Heartburn, Not MI?

“Accumulation of calcium in the arterial wall leading to reduced compliance would be expected to take years, but the increased risk of myocardial infarction reported by Bolland and colleagues occurred early after calcium supplementation (median follow-up of 3.6 years).”

Cleland et al suggest that the increased risk of MI may not be a true effect, because the increased risk of MI was not accompanied by an increase in mortality. “Calcium supplements could simply be causing gastrointestinal symptoms that could be misdiagnosed as cardiac chest pain,” they write, adding that even if the supplements are safe, the neutral effect on mortality “casts doubt on whether they are effective prophylaxis for fractures.”, even where active treatment for osteoporosis is being taken.

“In this analysis, 88% of the participants were women, and we know that cardiovascular disease in women is radically different from cardiovascular disease in men. The same holds true for cerebrovascular disease. There is something we need to get at, and at this point, no one has really been able to do so.”

Schindler also said that the real risk of MI appeared to be in people who took calcium supplements on top of high levels of dietary calcium. “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.”

He added that it is important to consider the potential safety concerns along with the benefits of bone health. “The benefits of calcium supplementation in older women with a low risk of fracture may not outweigh the potential cardiovascular risk.”

Finally, Schindler noted the absence in the meta-analysis of the Women’s Health Initiative, a large study that looked at the role of calcium supplementation with vitamin D in reducing osteoporotic fracture. “There are a lot of data that show that vitamin D is protective from a cardiovascular standpoint. They excluded studies with vitamin D probably because they are trying to isolate one variable. They didn’t want to cloud the picture.”

Ref: http://www.medscape.com/viewarticle/726859?src=mpnews&spon=34