Vitamin D deficiency linked to high BP

People with lower levels of vitamin D are more likely to have stiffer arteries and an inability of blood vessels to relax, according to a new study.

The findings by the scientists at the Emory/Georgia Tech Predictive Health Institute 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.

Ibhar Al Mheid, a cardiovascular researcher at the University conducted the study with Arshed Quyyumi, professor of medicine and director of the Emory Cardiovascular Research Institute.

The 554 participants in the study were Emory or Georgia Tech employees –average age 47 and generally healthy who are taking part in the Center for Health Discovery and Well Being, part of the Emory/Georgia Tech Predictive Health Institute.

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 per cent had 25-hydroxyvitamin D levels considered deficient, or less than 20 nanograms per milliliter, and 33 per cent 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," said Al Mheid.

"We found that people with vitamin D deficiency had vascular dysfunction comparable to those with diabetes or hypertension," he said.

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.

The study was presented at the annual American College of Cardiology meeting in New Orleans.