Calcium supplements could increase risk of heart disease, a new study has found, but calcium rich foods may help to protect the heart.
The new research was carried out by scientists at the Johns Hopkins University School of Medicine in the USA and it builds on the findings of a number of previous studies.
The results show calcium supplements make people more prone to the build-up of plaque in arteries, which contributes to the risk of a heart attack.
The study was prompted in large part because the scientists wanted to build on previous research that had discovered that calcium supplements never actually make it to a person’s bones and instead accumulate in soft tissue and muscles, such as the heart.
The researchers, who worked with scientists from several other universities, collected medical information from more than 6,000 individuals over time to look at the risk factors and characteristics of cardiovascular disease.
The team of researchers focused on 2,742 participants who completed dietary questionnaires and had CT scans taken at the beginning of the study and 10 years later.
Calcium supplements lead to build-up of plaque
They found that people who used supplements showed a 22 percent increased likelihood of developing heart disease over the decade. This was after taking into account demographic factors such as exercise habits, smoking, weight, blood sugar and family medical history.
The research did find that those who consumed the highest levels of calcium from both foods and supplements were 27 percent less likely to develop heart disease. It reached that conclusion by comparing the 20 percent of participants with the highest calcium intake, from both diet and supplements, to the 20 percent with the lowest calcium intake.
However, that statistic looked at total calcium intake in people who took in the nutrient from food and/or supplements. Going a step further, the researchers separated out calcium intake by source. They found that people who took calcium supplements had a significant increase in the risk of plaque build-up in their arteries, as well as in their odds for heart disease, compared to people who didn't take the supplements.
The researchers said their findings give people reason to use caution when taking calcium supplements. It is better for people to get calcium from food such as dairy products, leafy green vegetables, and fortified cereal and juices, they said.
"We think the body metabolises supplements and dietary calcium differently," said Dr. Erin Michos, Associate Professor of Medicine at the Johns Hopkins University School of Medicine. "If you are worried about your bones, then get your calcium through food."
However, Dr Michos acknowledged that there were limitations to the study as it was observational and looked at patient data and she said that a larger, more extensive clinical trial now needs to be done.
The study is published in the Journal of the American Heart Association.