Can Vitamin D Lower Blood Pressure?

Vitamin D for hypertension made no big difference in new study

(RxWiki News) Supplementing their daily diet with extra doses of certain nutrients is how many people seek better health. Vitamin D is one supplement that some people take in hopes of lowering high blood pressure. But whether vitamin D actually reduces that problem is an ongoing question.

A new study found that vitamin D did not noticeably improve a common form of high blood pressure that especially affects older adults.

"Talk to your doctor about blood pressure management."

Miles D. Witham, PhD, of the University of Dundee Division of Cardiovascular & Diabetes Medicine in Dundee, Scotland, was lead author of this study.

This research involved a group of 159 patients who, on average, were 77 years old. All patients were at least 70 years of age.

From June 2009 through May 2011, Dr. Witham and his fellow researchers monitored what happened when roughly half of these patients took 100,000 IUs of vitamin D3 at four different points: the start of the study, then three months, six months and nine months later. The remaining participants took a placebo pill that contained no vitamins at those same points in time.

The researchers measured the participants' blood pressure before the study began and 24 hours after they took vitamin D or the placebo at those four intervals in time.

The blood pressure, of patients assigned to take vitamin D, dropped by roughly 1 percent from what it was before they took the supplement, Dr. Witham told dailyRx News. That drop was not enough to significantly reduce blood pressure, he said.

"The effect of the vitamin D was much smaller than the variation in blood pressure that we all experience throughout the day," Dr. Witham said.

"The change in blood pressure … may well have been due to chance. This result is disappointing, as it means that vitamin D is unlikely to help high blood pressure in older people, a group who often suffer from heart disease and stroke brought about by [high blood pressure]," he said.

Because medications to stabilize blood pressure often cause dizziness, adding them to prescription medicine that many older adults may already be taking can be hazardous, the researchers noted.

"New, simple, safe, and inexpensive ways of treating blood pressure in older people are highly desirable," the researchers wrote.

To analyze the effects of taking the vitamin or placebo pills, the researchers also measured such things as the stiffness of study participants' arteries — a sign of high blood pressure. The researchers also measured whether taking vitamin D changed how far, and with how much ease or difficulty, study participants could walk in six minutes' time.

Even though their study showed no benefits for older people with blood pressure who took vitamin D, these researchers wrote, “It is still possible, however, that vitamin D supplementation could have beneficial effects on cardiovascular health via non-blood pressure effects. And ongoing large randomized trials are due to report on this in the next few years."

This study was published August 12 in JAMA Internal Medicine.

National Health Service Research Scotland and the Scottish Government's Chief Scientist Office, which previously granted a fellowship to the lead researcher, funded the study.

Review Date: 
August 12, 2013