Among studies of patients with or at risk for osteoporosis, those who took calcium supplements were about 30% more likely to have an MI than those who did not, Ian Reid, MD, of the University of Auckland in New Zealand, and colleagues reported online in BMJ.
"As calcium supplements are widely used, these modest increases in risk of cardiovascular disease might translate into a large burden of disease in the population," the researchers wrote. "A reassessment of the role of calcium supplements in the management of osteoporosis is warranted."
Murray Favus, MD, an endocrinologist at the University of Chicago, said in an e-mail to MedPage Today and ABC News, "I am sufficiently concerned to advise those with high calcium supplement intake to limit calcium supplement use in favor of dietary sources until the risk of supplements can be sorted out."
Reid and his colleagues analyzed data from 11 randomized controlled trials that evaluated the use of calcium supplementation (at least 500 mg/day). They excluded studies that also administered vitamin D, which has been shown to have a cardiac benefit, in order to get a clearer picture of calcium's effect on the heart.
It is possible that calcium supplements elevate cardiovascular risk by increasing serum calcium levels, which have been associated with higher MI rates in observational studies, they noted.
Other possible mechanisms include an increase in vascular calcification or coagulability or altered vascular flow.
"Calcium supplements, given alone, improve bone mineral density, but they are ineffective in reducing the risk of fractures and might even increase risk, they might increase the risk of cardiovascular events, and they do not reduce mortality," John Cleland, MD, of the University of Hull in England, and colleagues wrote in an editorial published with the study.
"[Supplements] seem to be unnecessary in adults with an adequate diet," they added. "Given the uncertain benefits of calcium supplements, any level of risk is unwarranted."
Dr. Hedberg's Comment:
Calcium is not the issue with osteoporosis – it is much more complex than that. The first step to eliminating osteoporosis is to reduce inflammation in your body as this is a major factor in losing bone mineral density. The second is to optimize magnesium intake and follow and alkaline-forming diet. The more acidic you are, the more calcium is released from bone to buffer the excess acids. Exercise has been shown to build bone mineral density so this is a vital part of the program.
Adrenal and sex hormones must also be in balance to have optimal bone density. These include cortisol, DHEA, testosterone, estrogen, and progesterone. Once a woman becomes menopausal she can take all the supplements she wants but she will never build bone without her hormones in balance.
The limitation in this study is that it didn't look at calcium supplements combined with vitamin D. Vitamin D is important in calcium metabolism and can lower the risk of heart attack. I recommend calcium supplements in low doses of 250-500mg combined with vitamin D and all the other factors for building bone. I only make this recommendation if we are not building bone at the rate we would like to see. This is a very rare case however where we need to use calcium.
Save your money and stop taking calcium alone. It may increase your risk of heart attack.
Related posts: