A higher level of vitamin D improves vascular health and loweres blood pressure, according to researchers from the Emory University School of Medicine in the US.
The research examined 554 participants, at the average age of 47 and generally healthy.
The researchers discovered that a lower level of the 'sunshine vitamin' meant stiff arteries and an inability of blood vessels to relax. This could lead to high blood pressure and the risk of cardiovascular disease.
The average level of 25-hydroxyvitamin D in participants' blood was 31.8 nanograms per milliliter. 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 ability of participants' blood vessels to relax was examined by inflating and then removing a blood pressure cuff on their arms. Blood vessels must relax and enlarge to allow blood to flow back into the arm, and this was monitored by ultrasound.
Ibhar Al Mheid, MD, a cardiovascular researcher who led the study reports,"We found that people with vitamin D deficiency had vascular dysfunction comparable to those with diabetes or hypertension."
On the other hand, when participants increased their vitamin D levels, their vascular health was improved and blood pressure lowered. Al Mheid explains, "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."