Taking calcium supplements may increase the possibility of a heart attack or stroke. When this finding first surfaced last year, many doctors argued that the increased risk applied only to calcium supplements alone, without vitamin D. A new analysis, however, shows that calcium supplements may cause problems even when paired with vitamin D. The researchers analyzed data from 16,700 women in the Women’s Health Initiative and examined how many of them were already taking calcium supplements at the outset. In this study, women were not required to stop taking the vitamins and minerals they were already using.
Those who had not been taking calcium but were randomized to take 1,000 mg calcium and 400 IU vitamin D during the study had a 13 to 22 percent higher chance of a heart attack or other cardiovascular problem during the study. The researchers then analyzed data from other studies and found a consistent pattern. They suggest a re-evaluation of the use of calcium and vitamin D supplements, given that their analysis throws the safety of this widespread practice into question.
[BMJ, online April 19, 2011]