Seniors are often advised to take calcium supplements, but new research says the pills might significantly increase an aging person's risk of heart valve problems that contribute to heart failure.
People taking either calcium supplements alone or calcium with vitamin D had a higher risk of heart-related death or death from any cause compared with people not taking supplements, the researchers reported.
These folks also were more likely to need surgery to replace their aortic valve.
For example, results showed that people taking calcium plus vitamin D had a doubled risk of heart-related death, while those taking calcium alone were nearly three times as likely to need surgery to replace their heart valve.
"Taking additional calcium cannot be helpful, and may be even harmful," said senior researcher Dr. Samir Kapadia, chair of cardiovascular medicine with the Cleveland Clinic, in Ohio. "If you are taking additional calcium, you want to analyze your situation with an expert to assess whether it's absolutely necessary."
Aortic stenosis occurs when the aortic valve — the main outflow valve of the heart — stiffens or narrows, blocking blood flow from the heart out to the rest of the body.
"Normally, the valve opens to the size of a quarter," Kapadia said. "In about 5% of people more than 75 years of age, the valve gets calcified. Accumulation of calcium happens, so that the valve is not opening as wide as it normally should," he explained.
"When the valve opens less than the size of a dime, it is considered very critical and it is a risk for developing heart failure or death," Kapadia said.
Calcium supplements have been suspected as a contributor to aortic stenosis, since calcium meant for the bones can just as easily migrate to heart valves, the researchers said in background notes.
But until now, research into calcium and heart valve problems has mainly taken place in animals. At the same time, the prescription of calcium with vitamin D has risen sharply in recent years, particularly among postmenopausal women, the investigators noted.
To see whether calcium might contribute to heart valve problems, Kapadia and his colleagues tracked the heart health of over 2,600 patients who already had mild to moderate calcification of their aortic valve.
The patients' average age was 74, and they were tracked more than 5.5 years on average. Patients were divided into those taking calcium, those taking calcium plus vitamin D, and those not taking any supplements.
The study found that people taking calcium with vitamin D had an absolute risk of heart-related death of 13.7 deaths per 1,000 person-years, compared with 5.8 deaths per 1,000 person-years in people not taking any supplements. (Person-years is the product of number of years times number of members of a population who have been affected by a certain condition.)
Supplemental calcium plus vitamin D increased risk of death from any cause by 31%, while calcium alone was linked to a 24% higher risk of all-cause mortality, the study found.
The results were published online April 25 in the BMJ.
Dr. Matthew Tomey, a cardiologist with Mount Sinai Morningside in New York City, noted that the development of aortic stenosis closely resembles the way bone normally forms.
Because of that, "the concept of calcium supplementation as a modifier of aortic stenosis disease progression is interesting," said Tomey, who wasn't involved in the study.
However, he cautioned that since this is an observational study, it cannot establish a clear cause-and-effect link between calcium supplements and heart valve problems.
"The findings of the study are nonetheless hypothesis-generating and underscore the need for a randomized study of benefits and risks of commonly used supplements for cardiovascular health," Tomey said.
"We would do well to remember that 'more' is not always 'more' — supplements can be double-edged swords," Tomey concluded.
Kapadia said that aging people would be better off getting their recommended calcium through their diet, and should talk to their doctor about their bone health concerns.
He noted that vitamin D — which your body requires for bone to absorb calcium — by itself did not cause any heart health problems among the patients in his study. And there's evidence that another supplement, vitamin K2, can "help the calcium go to the bone rather than the heart," Kapadia added.
People diagnosed with bone-thinning osteoporosis also have many other medications available to them outside of calcium supplements, Kapadia said. These include bisphosphonates, hormone therapy and bone-building drugs.
Dr. S. Allen Luis, an associate professor of medicine at the Mayo Clinic in Rochester, Minn., isn't rushing to judgment based on these study results. Besides calcium supplements, "there can also be a number of other factors — including diet, other medication use or medical problems that the person has — that also exist which may not have been taken into account," Luis said.
Also, a number of other studies have not shown associations between calcium supplement use and heart disease. "While these findings are very interesting, I think that this needs to be explored further," he added.
If someone has osteoporosis, Luis advised looking at the risks for the person as a whole. "In this case, we need to balance against potential risks of broken bones or fractures related to osteoporosis. These are very important to prevent due to the significant impact that they have on people's life," he said.