Vitamin D May Reduce Risk of Death from Heart
Disease.
SAN FRANCISCO: Women who use vitamin
D supplements may have a reduced risk of mortality from coronary heart disease
than women who do not, according to Paul Varosy, M.D., and colleagues from the
University of California, who presented their findings at the American Heart
Association's Asia Pacific Scientific Forum on April 23 in Honolulu. Varosy and
his colleagues analyzed data from the Study of Osteoporitic Fractures (SOF).
The investigators studied 9,704 ambulatory women
(age 65 and older) who were enrolled in SOF, with 4,273 women reporting taking a
supplement that contained vitamin D. However, it is unknown what amounts of
vitamin D the women were taking, or in what form. Researchers then analyzed the
information to discover if there was a link between vitamin D intake and the
risk of death from cardiovascular events. This link was studied because earlier
research had suggested that low blood levels of vitamin D might play a role in
the calcification that can contribute to heart disease. In addition, co-author
Warren S. Browner, M.D., noted that women with osteoporosis are more likely to
die of cardiovascular diseases than women without osteoporosis.
During a mean follow-up of 11.3 years, 448 women
who had enrolled in SOF died from coronary heart disease, with risk of mortality
37 percent lower in women who reported taking vitamins. After adjusting for
major cardiac risk factors, calcium supplement use and self-reported health
status, the risk of coronary heart disease mortality was 31 percent less in the
women who reported supplement use. Researchers concluded that older women who
use vitamin supplements that contain vitamin D are at decreased risk for
coronary heart disease mortality, although more research would be needed to make
any definitive claims in this realm. "At this point, it is really early," Varosy
said. "In fact, I'm still somewhat skeptical--enough that I don't think it's
right for me to advocate that anyone go out and start taking vitamin
D-containing supplements for the purpose of lowering heart disease risk."
One of the reasons to be skeptical of these
results is the fact that exact vitamin supplement use is unknown, as is dietary
information, according to Varosy. Additionally, he noted that multivitamin
supplement use could impact these results, as could vitamin D intake from the
sun. All four research centers in which SOF patients were enrolled were within 4
degrees latitude of each other, making it impossible to determine whether
sunshine affected the study, according to Varosy.
"We're planning on studying dietary intake and
the effect of latitude, and we're planning to find other places where we can
sort out the issue of whether it's vitamin D or other components," he explained.
"But the ones that are of the biggest concern to us are vitamin B6, vitamin B12
and folic acid, which are in multivitamin tablets. Those together have been
shown pretty well to lower levels of homocysteine, which is an important risk
factor for heart disease."
The researchers did explore this avenue a bit in
the SOF study by analyzing a few hundred cases for vitamin B intake and
homocysteine blood levels. It was determined that people who said they were
taking supplements had about a 25 percent higher level of vitamin
D--specifically 25-hyrodxyl vitamin D, a marker of vitamin D status. In
addition, homocysteine levels in patients who mentioned taking supplements were
approximately 10 percent lower than their non-vitamin counterparts. According to
Varosy, this is not incredibly significant and might account for a 6 percent
lower risk of heart disease, although it is not possible at this point to
attribute these effects to vitamin D intake, as it could be other factors in
multivitamins.
"There are well-established reasons for taking
calcium and vitamin D for the prevention of osteoporosis in women who are
predisposed," Varosy said. "Anyone who is thinking about doing it, however,
should talk to their doctor. That said, the downsides of taking calcium or
vitamin D are very minimal. . However, even with that, again, most people would
say it's too early to have people start to take vitamin D for [cardiovascular
health]. We need a lot more research before we can really recommend that on a
wholesale basis." |
