(Ivanhoe Newswire) -- The risk of having a heart attack and other cardiovascular events, particularly in older women, may be influenced by their calcium supplements with or without vitamin D, according to a new study.

Older postmenopausal women are often prescribed calcium supplements to maintain bone health; some contain vitamin D, and others do not. The Woman’s Health Initiative (WHI) study was conducted over a seven-year span evaluating more than 36,000 women to determine the cardiovascular effects of taking calcium with vitamin D. However, many of the women in the study were previously taking personal calcium supplements, and there became a concern for obscured results.

Professor Ian Reid from the University of Auckland along with his team of researchers reanalyzed the WHI study results in an attempt to estimate the effects of calcium supplements with and without vitamin D.

Data was gathered from 16,718 women in the study who were not previously taking personal calcium. The researchers found an increased risk of cardiovascular events, especially heart attacks for women taking calcium with vitamin D supplements. On the other hand, the study revealed women who were previously taking personal calcium and vitamin D supplements did not have any changes in their cardiovascular risks.

High blood calcium levels are linked to hardening of the arteries (calcification), and the researchers believe after taking the calcium supplement, an abrupt change in blood calcium levels produce an adverse effect. Also, data from 13 other studies involving 29,000 people have shown consistent increases in heart attack and stroke related to taking calcium supplements, with or without vitamin D.

Others are skeptical about the evidence linking calcium supplements with cardiovascular problems. In an accompanying editorial, Professors Bo Abrahamsen and Opinder Sahota are quoted as saying that due to the study’s limitations: "It is not possible to provide reassurance that calcium supplements given with vitamin D do not cause adverse cardiovascular events or to link them with certainty to increased cardiovascular risk. Clearly, further studies are needed, and the debate remains ongoing."