Over the past decade, a number of studies have raised questions about whether calcium supplements might contribute to heart disease or stroke. Just this month, a study of U.S. adults found that supplement users were more likely than nonusers to have plaque buildup in their heart arteries. (Calcium is a component of artery-clogging “plaques.”)
But a new research review, commissioned by the National Osteoporosis Foundation (NOF), has come to a different conclusion. On balance, the review found, the evidence doesn’t support a connection between calcium supplements and heart disease or stoke.
As long as people don’t go overboard, calcium supplements should be considered “safe from a cardiovascular standpoint,” say the guidelines from the NOF and the American Society for Preventive Cardiology. Getting calcium from foods such as milk, yogurt and tofu is still preferred, the groups say.
The guidelines and evidence review were published online Oct. 24 in the Annals of Internal Medicine.
The researchers analyzed 31 studies. Four of them were clinical trials, where older adults (mostly women) were randomly assigned to take calcium, with or without vitamin D.
None of those trials showed that supplement users had higher risks of heart disease, stroke or death than participants given placebo pills, the review found.
The rest of the studies the Tufts team analyzed were observational: They looked at the relationship between people’s calcium intake, from diet or supplements, and their risk of heart disease or stroke. Again, the researchers found the studies showed no consistent connection between higher calcium intake and higher cardiovascular risks.
But Dr. Erin Michos, associate director of preventive cardiology at John Hopkins University School of Medicine in Baltimore, disagrees. In her own study, published earlier this month, Michos found that supplement users were about one-quarter more likely than non-users to develop calcium buildup in their arteries over 10 years. “They are known to cause bloating, constipation and kidney stones,” Michos said. What’s more, she added, the evidence that calcium supplements prevent bone fractures is actually “not very clear.”
An editorial published with the guidelines also offered some words of caution. “The preponderance of evidence does not support cardiovascular adverse effects” from calcium supplements wrote Dr. JoAnn Manson, from Harvard Medical School, and Dr. Karen Margolis, of the HealthPartners Institute in Minneapolis. But the editorial authors agreed that calcium supplements do have side effects. And they urged people to take moderate supplement doses, but only if their diets are deficient in calcium.
It must be difficult for Dr. Michos to have her study refuted within a month of being published. I wrote a blog about another flawed study on calcium and dementia just last month.
The guidelines from the Institute of Medicine recommends 1,000 mg of calcium per day for young adults. That recommendation goes up to 1,200 mg per day for women older than 50 and men older than 70. Americans typically get as much as 500 mg per day from food sources. Most of us have to supplement to reach the RDA (recommended daily allowance).
As I noted in last month’s blog on calcium, calcium is used by the body to strengthen vulnerable plaque. Just because we can image calcium on high speed CT to identify vulnerable plaque being saturated with calcium doesn’t make it bad. It’s not the enemy, but rather a lifesaving friend in cardiovascular disease.
The Bottom Line:
I suggest you supplement your diet with 500 mg of calcium daily. Avoid calcium carbonate and coral calcium. Review last month’s blog on calcium and dementia for more insight. Finally, vary the source of calcium.
I just switch brands every other bottle, alternating between my two favorites.