Vitamin D not effective for lowering blood pressure

A wide-ranging review of clinical trial data led by researchers at the University of Dundee has found that the use of vitamin D to lower blood pressure is ineffective.

In an article published online by JAMA Internal Medicine the research team led by Dr Miles Witham, of the School of Medicine at Dundee, conclude that vitamin D should not be used to treat hypertension or to lower blood pressure.

Intervention studies have produced conflicting evidence on the blood pressure-lowering effect of vitamin D. An increasing number of clinical trials of have studied vitamin D and cardiovascular health, according to the study background.

Dr Witham and colleagues from Dundee led a global consortium - involving collaborators from the University of Aberdeen and Cambridge University Hospitals NHS Trust in the UK, Australia, New Zealand, India, USA and Europe - to analyse clinical trial data and individual patient data with regard to vitamin D supplementation and blood pressure.

The authors included 46 trials where vitamin D had been used to try and lower blood pressure (4,541 participants) and individual patient data were obtained for 27 trials (3,092 participants).

In both clinical trial and individual patient data, no effect of vitamin D supplementation was seen on systolic blood pressure or diastolic blood pressure.

“Large studies have shown that people with low vitamin D levels tend to have higher blood pressure,” said Dr Witham. “It hasn’t been clear though whether giving vitamin D to people actually lowers their blood pressure as individual trials have been too small to find out the answer.

“By combining all of these trials into one analysis, we have been able to show that taking vitamin D supplements doesn’t lower your blood pressure – even if you start with low vitamin D levels or a high blood pressure.

“This is important as blood pressure is one of the things that people had thought vitamin D might be used for and there are some practitioners who already suggest that patients with high blood pressure should take vitamin D.

“Our work shows that this doesn’t work, and so vitamin D cannot be recommended as a way to help control high blood pressure. Vitamin D can help reduce falls and fractures in older people, and might still have other health benefits, but we need to wait for the result from further large clinical trials before we know if more widespread use of this medication is safe or worthwhile.”

Roddy Isles
Head of Press
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