LOS ANGELES, April 3 (Xinhua) -- People with lower levels of vitamin D are more likely to have stiffer arteries and an inability of blood vessels to relax, U.S. researchers have found.
This finding also applies to people who are in general good health, according to researchers from the Emory University School of Medicine.
The researchers presented their findings on Sunday at the annual American College of Cardiology meeting in New Orleans.
Impaired vascular health in correlation with lower vitamin D levels contributes to high blood pressure and the risk of cardiovascular disease, the researchers say.
The study involved 554 participants, with the average age of 47 and generally healthy.
The average level of 25-hydroxyvitamin D (a stable form of the vitamin 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.