Taking vitamin D in winter could lower BP
MedWire News: A small study has found that hypertensive patients with vitamin D insufficiency have significantly reduced blood pressure (BP) during winter months when taking vitamin D supplements.
The findings of the randomized, placebo-controlled, double-blind study were reported at the 22nd European Meeting on Hypertension and Cardiovascular Protection in London, UK, by Thomas Larsen (Hostelbro Hospital, Denmark).
"Probably the majority of Europeans have vitamin D deficiency, and many of these will also have high BP," Larsen pointed out in a press statement.
"What our results suggest is that hypertensive patients can benefit from vitamin D supplementation if they have vitamin D insufficiency.
"Vitamin D would not be a cure for hypertension in these patients, but it may help, especially in the winter months," he added.
For the study, Larsen and team randomly allocated 130 patients with hypertension to a daily oral dose of 75 µg cholecalciferol or placebo for 20 weeks. All patients were Caucasians who resided in Denmark.
Baseline examination took place from October to November, when cutaneous vitamin D synthesis is absent, due to a lack of sunlight, which is its main source. The primary endpoints of the study included 24-hour ambulatory BP, pulse wave velocity, and central BP obtained using applanation tonometry.
Other endpoints included serum 25-hydroxyvitamin D [p-25(OH)D], a measure of vitamin D, serum Ca2+, and serum parathyroid hormone levels.
The study was completed by 112 patients with a mean age of 61 years. Compared with placebo, cholecalciferol caused a significant increase in p-25(OH)D level by a mean of 62 nmol/L, an increase in p-Ca2+ level by 0.01 nmol/L, and suppression of p-parathyroid hormone by 0.97 pmol/L.
There were no significant differences in 24-hour ambulatory BP between placebo and vitamin D patients.
However, in patients with a p-25(OH)D level of less than 80 nmol/L (defined as vitamin D insufficiency; n=92), those who received cholecalciferol showed a borderline significant reduction in both systolic BP (by 3.7 mmHg) and diastolic BP (by 2.7 mmHg) compared with placebo.
Furthermore, in all patients, central systolic and diastolic BP was reduced by a significant 6.8 mmHg and 1.7 mmHg, respectively, compared with placebo.
There was no significant difference between the placebo and cholecalciferol groups in terms of pulse wave velocity.
European Society of Hypertension Vice-President, Anna Dominiczak (University of Glasgow, UK) commented: "These results show a significant reduction in central systolic BP in patients taking the vitamin D supplement for 20 weeks, when compared to the placebo group."
Echoing Larsen's comments during his presentation, she stressed: "This is an initial study, so it needs to be confirmed, but it is potentially interesting as part of an overall strategy for managing hypertension in patients with low levels of Vitamin D."
By Piriya Mahendra