Vitamin D supplements are ineffective at controlling blood pressure (BP) and should not be used as an antihypertensive agent, according to a meta-analysis of randomised controlled trials (RCTs).
Vitamin D had no effect on systolic BP and diastolic BP (p=0.97 and p=0.84, respectively for RCTs and p=0.27 and p=0.38, respectively for individual patients). [JAMA Intern Med 2015;doi:10.1001/jamainternmed.2015.0237]
“The results do not support the use of vitamin D or its analogues as an individual treatment for hypertension or as a population-level intervention to lower BP,” said lead author Dr. Miles Witham from the University of Dundee, Dundee, Scotland. “The lack of efficacy of vitamin D treatment on BP also argues against routine measurement of25-hydroxyvitamin D [25OHD] levels in patients with hypertension.”
The analysis included studies that used vitamin D for a minimum of 4 weeks for any indication, published between January 1966 and March 2014. Nearly 7,600 participants were involved in the study.
Subgroup analysis did not reveal any baseline factors predictive of a better response to treatment. There were also no significant differences between patients with or without diabetes, those taking or not taking angiotensin-converting enzyme (ACE) inhibitors, irrespective of BP, parathyroid hormone, and 25OHD levels.
Witham however said there are a few caveats to the study, among them inclusion of single-centre trials and background cardiovascular medications. Other potential confounders are ageing, obesity, smoking, and inactivity, which could have influenced the results.
Previous studies have linked low levels of vitamin D with elevated BP and future cardiovascular events. Intervention studies however yielded conflicting findings.