Calcium, Vitamin D Supplements of Questionable Benefit
By Rose Hoban
Chapel Hill, NC
23 February 2007
The Women's Health
Initiative has followed more than 150,000 post-menopausal women for
more than to a decade. The continuing study has yielded results about
estrogen replacement therapy, hip fracture risk, and now, the effect of
calcium and vitamin D supplements on heart disease.
Dr. Judy Hsia leads the Initiative for
George Washington University hospital in Washington, DC. She says many
women take calcium and vitamin D to strengthen their bones, and
researchers wondered if the supplements might have other effects.
"Because we were tracking all these women for this prolonged period of
time, we also looked at other outcomes," she explains, "one of which
was whether calcium and Vitamin D prevented heart disease or maybe made
heart disease worse."
There have been arguments on both sides of
that question. Past research has indicated that calcium can contribute
to the buildup of coronary artery blockages. But other research shows
that women taking calcium and vitamin D have better weight control and
lower blood pressure, reducing those risk factors for heart disease.
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Research cardiologist Judy Hsia |
Hsia
says there were 36,000 women in this part of the study, ranging in age
from 50 to 79 years old. For seven years, half took supplements of
1,000 milligrams of calcium with 400 international units of vitamin D.
The other half took a placebo pill that looked the same. "And we
counted up the number of heart attacks and coronary deaths and strokes
in each treatment group and it turned out there was a balance." She
says the numbers were essentially the same in the active treatment
group and the placebo group.
So, she concludes, the many women around
the world who take calcium and vitamin D to protect their bones
shouldn't stop taking the supplements. "They don't need to worry that
they may be making heart disease worse. On the other hand," she adds
with a rueful laugh, "they cannot expect that these will improve their
cardiovascular health either!"
But Hsia also says the supplements may not
have much impact on bone strength. Researchers found that while taking
calcium and vitamin D increased bone density in women, it really didn't
reduce the incidence of hip fracture. She suggests that the recommended
amount of vitamin D may be too low, and should be studied further. The appear in
Circulation, the Journal of the American Heart Association.
From VOA News
