April 20th, 2011

New WHI Analysis Links Calcium Supplements to CV Risk

A new analysis may renew concerns that the combination of calcium supplements and vitamin D might increase cardiovascular risk. The link has been proposed before, but the Women’s Health Initiative (WHI) found no additional risk. Now, however, in an article appearing in BMJ, Mark Bolland and colleagues point out that more than half the 36,000 women in the WHI were taking calcium supplements at the start of the trial.

In a reanalysis of data from the 16,718 WHI participants who were not taking calcium supplements at the trial’s start, the investigators found a 16% increase in the risk for MI and stroke in the group randomized to calcium supplements and vitamin D compared with placebo (P=0.05). A meta-analysis combining the new WHI data with data from previous trials turned up a similar pattern of increased CV risk associated with calcium supplements. The authors did not find a dose-response relationship between calcium supplements and CV risk. They speculate that “the abrupt change in plasma calcium concentration after supplement ingestion causes the adverse effect, rather than it being related to the total calcium load ingested.” They conclude that “a reassessment of the role of calcium supplements in osteoporosis management is warranted.”

However, in an accompanying editorial, Bo Abrahamsen and Opinder Sahota write that “insufficient evidence is available to support or refute the association.” They write that further studies are needed to resolve the ongoing debate.

2 Responses to “New WHI Analysis Links Calcium Supplements to CV Risk”

  1. Jean-Pierre Usdin, MD says:

    these studies are really difficult to understand (for me)!
    what is the take home message?
    few months ago it seemed evident that low plasma vitamin D levels may be considered as a risk factor for CV diseases.
    now an abrupt change in calcium (and vitamin D?) can increase (slightly) cardiovascular events in women.
    the pendulum is swinging too fast.
    In an interview to Journal Watch ( http://www.jwatch.org Podcast 119 by Joe Elia) Ian Reid one of the co authors of “WHI CaD revisited” said: oral Calcium supplement can prevent 3 fractures in 1 000 women in 5 years and may provoke 6 CV accidents in the same period. Food calcium is sufficient, he conclude.
    So no more Calcium and vitamin D?
    dr Usdin.

    Competing interests pertaining specifically to this post, comment, or both:
    no conflicts of interest.

  2. Robin Motz, M.D., Ph.D. says:

    Wait for the next two or three studies.