Doctors are commonly asked by their patients whether calcium pills will lead to deposits of calcium in the blood vessels. Such calcium deposits are known to be linked to blood vessel blockage and plaque and to predict higher risk of heart attack and stroke. To answer this question, CAC levels were measured by cardiac computed tomography (CT) imaging in 754 women participating in the WHI calcium/vitamin D supplementation trial. No previous study had examined the relationship between supplementation with calcium and/or vitamin D and CAC in the setting of a randomized clinical trial, and the relationship between these supplements and clinical cardiovascular events remains uncertain.
The researchers compared CAC scores among women who received calcium (1000 mg of elemental calcium daily) plus vitamin D3 (400 IU daily) for an average of 7 years versus those who received placebo. The women were aged 50-59 at the time of study enrollment. At the end of the trial, the CAC scores in the two groups were similar and there was no evidence that treatment had increased calcium deposits in the coronary arteries. This was true even for women who were taking moderate-to-high doses of calcium and/or vitamin D on their own outside of the study, and had total vitamin D intakes of 1000 IU/d or higher, or calcium intakes above 1800 mg/d.
“This study provides reassuring evidence that moderate doses of calcium and vitamin D supplements do not increase calcium deposition in the coronary arteries. Thus, women need not avoid these supplements and sacrifice bone health due to concern about such a risk”, said JoAnn Manson, MD, Chief of Preventive Medicine at Brigham and Women’s Hospital and one of the Principal Investigators of the Women’s Health Initiative. Manson emphasized that it remains unclear whether supplementation with higher doses of calcium or vitamin D would influence CAC levels.
Manson and her colleagues are testing the role of vitamin D at a dose of 2000 IU/d in preventing cardiovascular disease and cancer. The study will be done in women aged 65 and older and men aged 60 and older and will include participants from throughout the United States. More information about the study is available at vitalstudy.org or by calling 1-800-388-3963.