Oral Calcium supplements intake to a significant 30% increased risk for heart attack.
This issue of “Staying Well” focuses on rethinking calcium recommendations. In the past, calcium concerns have focused on bone health and on how to get enough calcium. Adequate calcium intake recommendations developed by the Food and Nutrition Board at the Institute of Medicine say that children and teens 18 years of age or younger need 1300 mg daily, and adult men and women 19 to 50 years of age need 1000 mg daily. After age 50 years, the Institute of Medicine recommends even more calcium, and daily adequate intake increases to 1200 mg.[1,2] Now, a study in BMJ raises concern that supplemental calcium may have an inadvertent adverse outcome: It could hurt your heart.
Calcium and Heart Woes
In this meta-analysis of 15 randomized blinded placebo-controlled trials. Dr. Mark Bolland from the University of Auckland in New Zealand and colleagues evaluated calcium supplement use (at least 500 mg daily) in more than 12,000 patients older than 40 years of age. The findings were surprising: The pooled results linked calcium supplement intake to a significant 30% increased risk for heart attack. A tendency to increased risk for stroke and sudden death was also seen, but this result was not significant. Of note, cardiovascular outcomes were not a primary endpoint in any of the individual trials. Proposed mechanisms for the higher risk include increased blood coagulability and decreased blood vessel compliance due to calcium buildup in the arterial wall. On the basis of these findings, the authors postulate that treating 1000 people with calcium for 5 years would prevent 26 fractures but cause an additional 14 heart attacks.
This is not the first time that Dr. Bolland has studied calcium intake and cardiovascular outcomes. Two years ago, results of a randomized placebo-controlled study of 1471 postmenopausal women were published that linked calcium supplements with greater cardiovascular risk. That 2008 study by Bolland and colleagues was included in their 2010 meta-analysis.