Researchers at Johns Hopkins Medicine have analyzed 10 years of medical tests on more than 2,700 people in a federally funded heart disease study, and have come up with the conclusion that taking calcium supplements can cause heart disease by building up plaque in arteries and lead to cardiovascular problems.
The research was carried out to better inform and educate individuals about the heart disease. According to the US Centers for Disease Control and Prevention (CDC), coronary heart disease kills over 370,000 people each year in the US. More than half of women over 60 take calcium supplements, mostly without consulting a physician as they believe it will reduce their risk of osteoporosis.
An estimated 43% of American adult men and women take supplements that include calcium, according the National Institutes of Health. Due to the risks associated with these supplements, the researchers have asked the people to consult a physician before taking any supplement.
The researchers, however, went on to say that a healthy balanced diet rich in foods containing calcium appears to be safe. They further added that their research only links an association between calcium supplements and atherosclerosis, and does not mean a cause and effect relation.
Associate Director of Preventive Cardiology and Associate Professor of Medicine at the Ciccarone Center for the Prevention of Heart Disease at the Johns Hopkins University School of Medicine, Erin Michos, MD, MHS, said, “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.”
The researchers were focused to investigate the effects of calcium on the cardiovascular system since previous studies already showed that calcium supplements can cause heart disease as calcium is not completely absorbed, hence it is most likely to get deposited in tissues, according to nutritionist John Anderson, PhD, Professor Emeritus of Nutrition at the University of North Carolina at Chapel Hill’s Gillings School of Global Public Health and a co-author of the study.
Scientists have already confirmed that as a person grows older, calcium plaque builds up in the body’s main blood vessels, the aorta and other arteries, which can cause massive blood flow blockage that could eventually lead to a heart attack.
The researchers studied data from a long-running research project funded by the National Heart, Lung and Blood Institute. The researchers used information from the Multi-Ethnic Study of Atherosclerosis project, which included more than 6,000 people observed at six research universities, including Johns Hopkins. The data included 2,742 of these participants who completed dietary questionnaires and two CT scans spanning 10 years apart.
The selected individuals ranged in age from 45 years old to 84 years old, and 51% were female, while rest were males. 41% were Caucasian, 26% were African-American, 22% were of Hispanic ethnicity and 12% were Chinese.
All participants were asked to answer a 120-part questionnaire at the start of the study about their dietary habits to calculate their calcium intake via dairy products, leafy green vegetables, foods rich in calcium such as cereals. The investigators also maintained records of drugs and supplements each participant took on a daily basis.
The investigators used cardiac CT scans to measure coronary artery calcium scores of the participants. Coronary artery calcium score is a measure of calcification in the heart’s arteries and a marker of heart disease risk when the score is above zero.
At the beginning, 1,175 participants showed plaque deposits in their heart arteries. The coronary artery calcium tests were repeated 10 years later to explore if their condition was newly developing or was slowly worsening into coronary heart disease.
For the purpose of proper analysis, the researchers divided the participants into five groups based on their total calcium intake, which included both calcium supplements as well as dietary calcium that they consumed.
After they adjusted the demographics for age, sex, race, exercise, smoking, income, education, weight, smoking, drinking, blood pressure, blood sugar and family medical history, the researchers separated 20% of participants with the highest total calcium intake, which was greater than 1,400 milligrams of calcium a day.
That group was found to be on average 27% less likely than the 20% of individuals with the lowest calcium intake, which was less than 400 milligrams of daily calcium, to develop heart disease.
After that, the researchers decided to focus their efforts to further investigate the differences among those consuming only dietary calcium and those using calcium supplements. 46% of the study participants used calcium supplements.
The researchers found that individuals taking calcium supplement had a 22% increased risk of having their coronary artery calcium scores rise higher than zero over the decade, which pointed towards a possibility of developing heart disease.
Among participants with highest dietary intake of calcium, which was over 1,022 milligrams per day, there was no increased risk of developing heart disease over the decade-long study period.
This study showed quite similar results to a previous study that highlighted the risk of using calcium supplements. The study concluded that taking calcium supplements might increase an elderly woman’s risk of dementia.
The five-year long study showed that women who had previously had a stroke and who regularly took calcium supplements at the beginning of the study were seven times more likely to develop dementia over the five-year period, compared to women who had a stroke but who did not take calcium supplements.