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.