People with healthy blood pressure levels tend to have higher levels of vitamin D than those with high blood pressure. But a new review of studies on vitamin D supplementation showed taking it did not lower high blood pressure.
Despite the fact that people with healthy blood pressure (BP) tend to have higher levels of vitamin D, there is no evidence the supplement can reverse high blood pressure, a new study found.
Writing in JAMA Internal Medicine, Miles Witham, BM, BCh, PhD, of the University of Dundee, Scotland, and colleagues reported on their analysis of 46 previously published trials of vitamin D.
“In both clinical trial and individual patient data, no effect was seen on systolic BP or diastolic BP due to vitamin D supplementation,” the team found.
“The results of this analysis do not support the use of vitamin D or its analogues as an individual patient treatment for hypertension or as a population-level intervention to lower BP,” they concluded.
The idea that vitamin D might lower BP seemed logical, initially, Witham wrote.
Biologically plausible mechanisms were there, including “the fact that vitamin D receptors are found on endothelial cells, smooth muscle cells, and myocytes,” and that the supplement “has been shown to improve endothelial function in some studies, reduce the production of pro-inflammatory cytokines, reduce activity of the renin-angiotension-aldosterone system and reduce parathyroid hormone levels.”
Any or all of those mechanisms might be a path for vitamin D to lower BP. But the data showed that was not happening.
“The results of this analysis add to the growing body of literature casting doubt on the ability of vitamin D supplementation to influence health outcomes beyond falls, fractures and possibly respiratory tract infection and all-cause mortality," he wrote.
The studies were of randomized placebo-controlled clinical trials that used vitamin D supplementation for a minimum of 4 weeks for any indication and reported BP data. Studies were included if they used either active or inactive forms of vitamin D or vitamin D analogues.
The researchers then extracted data on baseline demographics, 25-hydroxyvitamin D levels, BP and change in BP from baseline to the final follow up.