Women Taking Calcium Supplements May Risk Heart Health,
TUESDAY, April 19 (HealthDay News) -- More evidence is emerging
that women who take calcium supplements to prevent bone
deterioration may, in fact, be risking their heart health.
But even when added to previous studies with similar findings,
the new conclusions don't necessarily mark a death knell for
calcium supplements, say the authors of a study released online
April 19 in the
"There is a lack of consensus at the present time as to what recommendations should be regarding the use of calcium supplements," said study senior author Dr. Ian Reid, who fully expected that the new results will have a "significant impact on recommendations."
"Our own recommendation is to critically review the use of calcium supplements, since the data in this paper suggests that they do more harm than good," added Reid, who is professor of medicine and endocrinology at the University of Auckland in New Zealand.
"The cautious way forward seems to be to encourage people to obtain their calcium from the diet, rather than from supplements, since food calcium has not been shown to carry this increased risk of heart disease," Reid added.
A recent meta-analysis done by the same group of researchers
found a 27 to 31 percent increased risk of heart attacks in women
taking calcium without vitamin D.
Many older women take calcium supplements with or without
vitamin D to keep their bones strong, especially since that has
long been standard medical advice. In addition, the mammoth,
U.S.-government funded Women's Health Initiative (WHI) earlier
found no negative link between calcium and heart health.
But, as the current authors point out, more than half of the
women in that study were
already taking their own calcium supplements on top of what
they had been prescribed for the trial, which may have clouded the
For this analysis, the authors looked only at the 16,718 women
in the WHI who had not been taking personal calcium supplements
before entering the trial.
In this case, women who were randomized to take calcium and
vitamin D as part of the study protocol had a modest 13 to 22
percent increased risk of cardiovascular problems, particularly
heart attacks. Women in the control arm had no change in risk.
The case against calcium became stronger when researchers added
in data from 13 other, unpublished trials involving almost 30,000
women. Now the increased risk for heart attack was 25 to 30 percent
and, for a stroke, 15 to 20 percent.
While the authors speculate that an increased risk could be
biologically plausible given that calcium is connected with
hardening of the arteries, another expert thinks not.
While calcium does tend to be a marker of inflammation,
explained Dr. Philip Houck, assistant professor of internal
medicine at Texas A&M Health Science Center College of
Medicine, "lesions with calcium are actually more stable so there's
less of a chance of having a heart attack than in vessels that are
Moreover, the results may have been statistically significant
but that doesn't mean they're clinically significant, he added. "If
women have good reason to take calcium because their bones are
thin, then they should not be afraid of taking the calcium," said
Houck, who is also a cardiologist with Scott & White in Temple,
Dr. Susan V. Bukata, associate professor of orthopaedic surgery
at the University of Rochester Medical Center, said that the study
really doesn't provide enough information to make a definitive
Nevertheless, accumulating evidence has her urging patients to
get their calcium from their diet, rather than reflexively telling
them to take 1,200 milligrams of calcium a day. "With diet plus a
supplement combined, women should be getting 1,000- to
1,500-milligrams a day," she said.
And in an accompanying journal editorial, medical professors Dr.
Bo Abrahamsen and Dr. Opinder Sahota wrote that due to study
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."
The National Osteoporosis Foundation has more on
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