RODALE NEWS, EMMAUS, PA—There's not much argument over the fact that calcium is good for you. In addition to warding off osteoporosis, research suggests that it could help you live longer while also protecting against cancer. But a new study published in the British Medical Journal suggests that your sources of calcium matter. The study, which was actually a review of existing research, found that calcium supplements, but not calcium from food, may increase your risk of heart attack.
THE DETAILS: The authors narrowed down a list of 15 studies out of a total of 190 that had looked at calcium supplements and their impact on bone density, fractures, and blood pressure. The studies that were chosen included women over 40 who had taken at least 500 milligrams (mg) or more per day of calcium only, but who didn't take a calcium and vitamin D combination (because of vitamin D's health benefits, there was a chance that taking vitamin D may have had a protective effect). The original study authors were contacted and asked for any data on participants suffering from heart attacks or any other heart problems during the study.
Those who were taking calcium supplements saw a 31 percent increase in risk for heart attacks, and they also had a slightly higher risk of having a stroke and of sudden death. Interestingly, though, the risk doesn't seem to carry over to calcium from food. The authors point to another study in which the women with the highest level of calcium intake from their diets had a 30 to 40 percent lower risk of heart attacks than the women with the lowest calcium intake levels.
WHAT IT MEANS: Calcium supplements raise the level of calcium in the blood in a way that calcium from food does not, says the study's lead author Ian Reid, PhD, professor of medical and health sciences at the University of Auckland in New Zealand, adding that high levels of blood calcium can increase your risk of heart attack. Calcium supplements are also known to accelerate the buildup of calcium in artery walls, he says, which could lead to the increased risk of heart attack. But that doesn't necessarily mean you shouldn't be taking calcium supplements. On the other hand, taking calcium supplements without having a conversation with your doctor isn't smart either. "People should not just be self-prescribing calcium," he says. The best approach is to work with your physician to come up with a calcium plan that's appropriate for your health needs, so you can balance the risks and benefits of taking calcium supplements. For example, Reid's prior research found that calcium supplements can decrease the risk of bone fracture by 50 percent, an important benefit considering that recent studies suggest that bone-fracture rates have risen 55 percent over the past decade, largely due to diets deficient in vital bone-protecting nutrients.
Published on: August 9, 2010