Jan. 7, 2010 -- African-Americans are more likely than whites to die of
heart attacks, strokes, and other cardiovascular causes. Now intriguing new
research suggests that low vitamin D levels may help explain this
Darker-skinned people produce less vitamin D from the sun than those with
lighter skin, and studies show that blacks are far more likely to have lower
levels of the vitamin than whites.
Several recent studies also suggest that low levels of vitamin D are
associated with an increased risk for heart attack and stroke.
In an effort to examine the role of vitamin D in the racial disparity in
cardiovascular death, researchers analyzed data from a national health and
nutrition survey that included more than 15,000 people.
Vitamin D levels were measured at the time the survey was conducted, and the
participants were followed for up to 12 years.
Compared to everyone else in the study, the quarter with the lowest vitamin
D levels had a 40% higher risk of dying from heart attacks, strokes, and other
Blacks were 38% more likely to die of cardiovascular causes than
non-Hispanic whites, and the researchers concluded that most of this excess was
related to their lower vitamin D levels.
The findings suggest, but do not prove, that low vitamin D raises
cardiovascular risk, says study researcher Kevin Fiscella, MD, MPH, of the
University of Rochester School of Medicine and Dentistry.
Fiscella and co-researcher Peter Franks, MD, of the University of California
at Davis, published their study in the January/February issue of the Annals
of Family Medicine.
"The message is that vitamin D deficiency might be a major contributor to
cardiovascular deaths," he tells WebMD. "We really need clinical trials to
understand this association."
Fiscella points out that vitamin C, vitamin E, and beta-carotene were all
thought to lower heart attack and stroke risk just a few years ago. But the
early excitement was not borne out in clinical trials.
"We have had a lot of false hopes with various nutrients and vitamins," he
Vitamin D deficiency has traditionally been associated with bone and muscle
weakness, but recent studies also suggest that it may contribute to a host of
other conditions including diabetes, autoimmune diseases, and even certain
Fiscella says it is too soon to recommend taking vitamin D supplements to
improve heart health.
"We really don't know what the optimal levels are at this point, or if there
is a downside to taking double or triple the recommended amount," he says.
The National Osteoporosis Foundation recommends that adults under 50 get 400
to 800 international units (IU) of vitamin D a day and that older adults get
800 to 1,000 IU.
Current federal nutrition guidelines consider 200 IU of vitamin D daily
adequate for children and adults up to age 50 and 400-600 IU daily adequate for