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Calcium and Heart Disease

New Studies Create Confusion: Heart vs. Bones

You may want to think twice before reaching for those calcium tablets. Earlier this year, researchers threw women of a certain age into a tizzy with a paper suggesting that calcium supplements may hurt the heart while helping bones. The news unleashed widespread consternation, since many primary care physicians routinely advise  menopausal women to take calcium to prevent osteoporosis.

What the Data Shows

Increase in Heart Attack Risk

The paper took data from over 12,000 women enrolled in eleven different clinical trials and followed people who took calcium supplements of 500 mg or more without vitamin D supplementation. * The results of these trials suggest a 31 percent increase in the risk of  heart attack among participants. Based on this information, the authors estimated that if 1,000 people were treated with calcium supplementation for five years, 26 fractures would be prevented but 14 heart attacks would occur.

More Studies Needed

These results also echo findings from research conducted in 2006 and 2008 among healthy, older women who took calcium supplements. However, those trials were smaller studies, and in one trial, did not reach statistical significance.

While the news may not be as dire as it sounds, some doctors are now advising women to replace calcium tabs with yogurt, broccoli and sardines.

Weigh Your Risk: Talk to Your Doctor

"Clearly, each woman needs to talk to her primary care provider about her individual risk of bone disease and  heart disease to determine whether calcium supplementation is important to take. I would recommend that patients attempt to avoid the supplements if possible, and instead obtain their calcium from dietary sources," said Loryn Feinberg, MD, a cardiologist at the  CardioVascular Institute and director of its Women's Cardiovascular Health Program.

"If you do require calcium supplementation," Dr. Feinberg added, "speak with your primary care physician about other alternatives for preventing osteoporosis and fractures, as well."

Role of Vitamin D

Relationship to Heart Disease?

At the same time, Feinberg pointed out, "This analysis is not conclusive. We need future studies to look at this more closely. For example, the trials only involved patients taking calcium supplements without the addition of vitamin D. We have seen data suggesting that low vitamin D levels can increase the risk of heart disease, so there may indeed be a relationship between vitamin D deficiency and cardiac events."

Conflicting Evidence

"It would be interesting to determine if supplementing with both vitamin D and calcium offsets the increase in risk seen with calcium supplementation alone. One such trial, the Women's Heart Initiative, which looked at a different population of women (younger, more often using hormone replacement therapy) who were also taking vitamin D in addition to calcium, did not any find an increased risk of heart disease or stroke. Also, none of the trials in this study were designed to specifically look at the risk of heart disease. I think we need more information before coming to any absolute conclusions."

Food Sources Are Best

Food Sources Show No Risk

The good news is that the studies suggesting that calcium raises the risk of heart attacks point solely to calcium supplements. "Calcium obtained directly from food sources show no such risk. In fact, two studies of U.S. women showed an inverse relationship between dietary calcium intake and cardiovascular death, meaning that the greater the dietary intake, the lower the risk of death from heart disease and the main type of stroke," said Feinberg.

Toss the Tabs

Given the fact that calcium supplements only have a modest effect on increasing bone density, Feinberg recommends obtaining calcium through food rather than supplements. "Calcium obtained from dietary sources may be preferable and has not been associated with the potential increased risk of heart disease."

What You Can Do

Food Sources for Calcium

Dairy: yogurt, low-fat cheese, milk
Produce: spinach, kale, broccoli, turnip greens, bok choy, black beans, oranges
Protein: sardines, salmon, clams
Other: sesame seeds, almonds

More Tips

In addition, Feinberg counsels women to avoid smoking cigarettes or being underweight, since both can reduce bone density. She also advises weight-bearing exercise. "Taking advantage of opportunities for weight-bearing exercise may be easier than you think. You can strengthen bone density through walking, jogging, yoga, dancing, golf, tennis and lifting weights."

*Effect of Calcium Supplements on Risk of Myocardial Infarction and Cardiovascular Events: Meta-Analysis; Bolland MJ et al; BMJ 2010; 341:c3691. Conducted jointly by the Universityof Auckland, New Zealand, University of Aberdeen, UK and Dartmouth Medical School, NH, USA.

Contact Information

Women's Cardiovascular Health Program
CardioVascular Institute
Beth Israel Deaconess Medical Center
330 Brookline Avenue
Boston, MA 02215