A lack of vitamin D, even in
healthy people, is now linked
with stiff arteries and an
inability of blood vessels to
relax, based on new research
from the Emory/Georgia Tech
Predictive Health Institute.
The results of the study now add to evidence that
lack of vitamin D can lead to impaired vascular health,
contributing to high blood pressure and the risk of
cardiovascular disease. Study participants who
increased their vitamin D levels were able to improve
vascular health and lower their blood pressure.
The data was presented by cardiovascular
researchers at Emory University School of Medicine,
at the annual American College of Cardiology meeting
in New Orleans.
The 554 participants in the study were Emory or
Georgia Tech employees (average age 47) and are
generally healthy individuals. They are participating in
the Center for Health Discovery and Well Being of the
Emory/Georgia Tech Predictive Health Institute.
The average level of 25-hydroxyvitamin D (stable form
of vitamin D reflecting diet as well as production in the
skin) in participants' blood was 31.8 nanograms per
milliliter. In this group, 14 percent had 25-hydroxyvitamin
D levels considered deficient, or less than 20 nanograms
per milliliter, and 33 percent had levels considered
insufficient, less than 30 nanograms per milliliter.
The researchers monitored the ability of participants'
blood vessels to relax by inflating and then removing a
blood pressure cuff on their arms. To allow blood to flow
back into the arm, blood vessels must relax and enlarge,
a change that can be measured by ultrasound. The
researchers also made other measurements of smaller
blood vessels and examined the resistance to blood flow
imposed by the arteries.
Even after controlling for factors such as age, weight
and cholesterol, people with lower vitamin D levels still
had stiffer arteries and impaired vascular function, the
researchers noted. "We found that people with vitamin D
deficiency had vascular dysfunction comparable to those
with diabetesor hypertension," they explained.
Throughout the body, a layer of endothelial cells lines
the blood vessels, controlling whether the blood vessels
constrict or relax and helping to prevent clots that lead
to strokes and heart attacks.
"There is already a lot known about how vitamin D
could be acting here," researchers said. "It could be
strengthening endothelial cells and the muscles
surrounding the blood vessels. It could also be reducing
the level of angiotensin, a hormone that drives increased
blood pressure, or regulating inflammation."
Most Americans generally get the majority of their
vitamin D from exposure to sunlight or from dietary
supplements; fortified foods such as milk or cereals
are also a source. Specific foods, such as oily fish,
naturally contain substantial amounts of vitamin D.
Participants whose vitamin D levels increased over the
next six months, either from dietary supplements or
ample sun exposure, tended to improve their measures
of vascular health and had lower blood pressure.
Forty-two study participants with vitamin D insufficiency
whose levels later went back to normal had an average
drop in blood pressure of 4.6 millimeters mercury.
With the new findings showing the relationship between
vitamin D deficiency and vascular dysfunction, the
study has helped advance the understanding of the
importance of Vitamin D in preventing a common health
problem in aging adults. Further ongoing health studies
based on the Center's collection of health information
from participants will yield more discovery as the Center
continues to develop."
The Emory-Georgia Tech Predictive Health Institute
is a national leader in moving the practice of medicine
from a reactive, disease-focused system to a proactive
health-focused system. The initiative integrates research,
scholarship and education in an innovative effort aimed
at revolutionizing care of people to define, preserve and
prolong the health of individuals and of society.
Key areas of the Initiative include defining and measuring
health using optimal biomarkers of health and understand
their interrelationships, determining the best interventions
to optimize health throughout an individual's or a
population's lifetime.
Source:
Emory University (2011, April 3).
Vitamin D levels linked with health of blood vessels.
Editor's Note: This article is not intended to provide medical advice,
diagnosis or treatment.