A federally-funded heart disease study carried out at John Hopkins Medicine in Baltimore, Maryland analyzed the effect of calcium supplements on the cardiovascular system of more than 2700 participants.
While researchers have cautioned that their work only demonstrates a link between calcium supplements and heart disease and does not yet prove cause and effect, it was found that taking calcium in the form of supplements may increase the amount of plaque in the arteries, which can cause long-term damage to the cardiovascular system.
Conversely, a calcium-rich diet including dairy, leafy greens, and cereals was found to protect the heart against plaque build-up and damage, a finding which was published in the Journal of the American Heart Association (JAHA) in October.
Why do supplements cause damage?
Researchers recommend consulting with a medical professional before taking calcium supplements due to the growing scientific evidence that it could cause damage to the cardiovascular system.
Dr. John Anderson, a professor emeritus of nutrition at the University of North Carolina and the co-author of the study, says: “There is clearly something different in how the body uses and responds to supplements versus intake through diet that makes it riskier. It could be that supplements contain calcium salts, or it could be from taking a large dose all at once that the body is unable to process.”
Dr. Erin Michos, the associate professor of medicine at the Ciccarone Center for the Prevention of Heart Disease at the John Hopkins University School of Medicine, says: “When it comes to using vitamin and mineral supplements, particularly calcium supplements being taken for bone health, many Americans think that more is always better, but our study adds to the body of evidence that excess calcium in the form of supplements may harm the heart and vascular system.”
Previous studies have shown that calcium in the form of supplements rarely makes it to the skeletal system, particularly in elderly people. This means that it accumulates in the body’s soft tissue and the excess is excreted through urination, adding to the natural build-up of calcium in the cardiovascular system that has been associated with aging.
According to the National Institutes of Health (NHS), approximately 43% of American adults are taking supplements that contain calcium without being monitored by medical health professionals.
More than 370 000 people in the US die from coronary heart disease every year, according to the Centers for Disease Control and Prevention (CDC), and more than 50% of females over the age of 60 are taking calcium supplements in an effort to reduce the risk of osteoporosis and heart disease.
How was the link found?
The National Heart, Lung, and Blood Institute funded a 10-year multi-ethnic study that involved more than 6000 participants. After reviewing dietary questionnaires and the results of two CT scans over the 10-year period, 2742 participants were chosen for the detailed study, aged 45-84, with 51% female.
41% were white, 26% were African-American, 22% were Hispanic, and 12% were Chinese. To determine the dietary intake of calcium and how much came from supplements, researchers gave each participant a 120-part questionnaire to fill in while using cardiac CT scans to monitor coronary artery calcium scores. It was found that 1175 participants had plaque in their arteries and that those who had more than 1400 milligrams of dietary calcium per day from dietary sources were 27% less likely to develop heart disease.
46% of all participants used calcium supplements and were shown to have a 22% increase in coronary plaque build-up, which indicates the development of heart disease.
Dr. Michos concluded: “Based on this evidence, we can tell our patients that there doesn’t seem to be any harm in eating a heart-healthy diet that includes calcium-rich foods, and it may even be beneficial for the heart. But patients should really discuss any plan to take calcium supplements with their doctor to sort out a proper dosage or whether they even need them.”