The same vitamin D deficiency that can result
in weak bones now has been associated with an
increased risk of cardiovascular disease,
Framingham Heart Study researchers report in
Circulation: Journal of the American Heart
Association.
“Vitamin D deficiency is associated with increased
cardiovascular risk, above and beyond established
cardiovascular risk factors,” said Thomas J.
Wang, M.D., assistant professor of medicine at
Harvard Medical School in Boston, Mass. “The
higher risk associated with vitamin D deficiency
was particularly evident among individuals with
high blood pressure.”
In a study of 1,739 offspring from Framingham
Heart Study participants (average age 59, all
Caucasian), researchers found that those with
blood levels of vitamin D below 15 nanograms
per milliliter (ng/mL) had twice the risk of
a cardiovascular event such as a heart attack,
heart failure or stroke in the next five years
compared to those with higher levels of vitamin D.
When researchers adjusted for traditional
cardiovascular risk factors such as high
cholesterol, diabetes and high blood pressure,
the risk remained significant with a 62 percent
higher risk of a cardiovascular event in
participants with low levels of vitamin D
compared to those with higher levels.
Researchers observed the highest rate of
cardiovascular disease events in subset
analysis dividing 688 participants according
to high blood pressure status. After researchers
adjusted for conventional cardiovascular risk
factors, participants with hypertension and a
vitamin D deficiency had about 2 times the
risk of having a cardiovascular disease event
in five years.
Researchers also found an increase in cardiovascular
risk with each level of vitamin D deficiency.
“We found that people with low vitamin D levels
had a higher rate of cardiovascular events over
the five-year follow-up period,” Wang said. “These
results are intriguing and suggestive but need to
be followed up with further study.”
Study participants had no prior cardiovascular
disease and were tested for vitamin D status
and then followed for an average of 5.4 years.
The participants attended the offspring
examinations between 1996 and 2001. Researchers
obtained medical history, physical examinations
and laboratory assessments of vascular risk
factors. They also obtained medical records
related to cardiovascular disease.
Overall, 28 percent of individuals had levels
of vitamin D below15 ng/mL and 9 percent had
levels below 10 ng/mL. Although levels above
30 ng/mL are considered optimal for bone metabolism,
only 10 percent of the study sample had levels in
this range, researchers said.
During follow-up:
* 120 participants developed a first cardiovascular
event including fatal and nonfatal coronary heart
disease;
* 28 participants had fatal or nonfatal cerebrovascular
events such as nonhemorrhagic stroke;
* 19 participants were diagnosed with heart failure;
and
* 8 had occurrences of claudication, fatigue in the
legs during activity.
“Low levels of vitamin D are highly prevalent in
the United States, especially in areas without
much sunshine,” Wang said. “Twenty to 30 percent
of the population in many areas has moderate to
severe vitamin D deficiency.”
Most of this is attributed to lack of sun exposure,
pigmented skin that prevents penetration of the
sun’s rays and inadequate dietary intake of vitamin D
enriched foods, researchers said.
“A growing body of evidence suggests that low levels
of vitamin D may adversely affect the cardiovascular
system,” Wang said. “Vitamin D receptors have a
broad tissue distribution that includes vascular
smooth muscle and endothelium, the inner lining
of the body’s vessels.
Our data raise the possibility that treating
vitamin D deficiency, via supplementation,
lifestyle and dietary measures, could
reduce cardiovascular risk.
According to Dr. Robert O. Young, a research scientist
for the pH Miracle Center, states, "the best source
of Vitamin D is from direct sunlight with a minimum
daily dose of 30 minutes a day."
"This daily dose of Vitamin D is helpful in buffering
dietary and metabolic acids and energizing the body."
"Direct sunlight is the fastest way of recharging
the body cells with Vitamin D - one of the body's
most powerful anti-oxidants in helping to maintain
its alkaline design."
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