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Vitamin D supplementation did not lower blood pressure in older patients with high blood pressure in a new study.
The study was published online August 12 in the journal JAMA Internal Medicine.
It included 159 patients, average age 77, with a common type of high blood pressure called isolated systolic hypertension. They were given vitamin D supplementation or a placebo every three months for one year.
Vitamin D supplementation did not lower blood pressure or improve any other measures of cardiovascular health, according to a journal news release.
"It is still possible, however, that vitamin D supplementation could have beneficial effects on cardiovascular health via non-blood-pressure effects, and ongoing large randomised trials are due to report on this in the next few years," said Miles Witham, of the University of Dundee in Scotland, and colleagues.
One cardiologist found the research intriguing, if disappointing.
"The findings are of interest because low levels of vitamin D have been associated with all of these conditions, and there was a hope that replacing vitamin D with supplements would help correct these conditions known to be causes of heart attack and stroke," said Dr Nicholas DuBois, a cardiologist at Mount Sinai Medical Center in New York City. "Being able to modify that risk with a vitamin that has no side effects and is low in cost would be a fabulous advance for cardiovascular protection.
Very small study
"The key to me for this study is first that it is very small, and so has statistical ability to see only a large impact of the vitamin D supplement," DuBois added. "In other words, there would have to be a very large drop in BP [blood pressure] for this study to detect any effect. A larger study with several thousand patients could detect a more subtle change."
He added: "For me, the current study does not change much for current practice. If vitamin D levels are low, I will try to replete them, acknowledging that it's not certain how much benefit this does... I certainly will not begin using vitamin D in the hopes of controlling high blood pressure."
Another heart expert agreed that the research had its strengths and weaknesses.
"Several advantages of this study include its ability to randomly select a group of participants from a wide geographic area in England, all of whom were on several other medications for cholesterol, blood pressure or diabetes," said Dr Nicholas Gargiulo, a vascular surgeon at North Shore-LIJ's Plainview Hospital, in Plainview, N.Y.
However, the research lacked ethnic diversity and the way blood pressure was measured in the study was not consistent, he added.
"As with most research, a note of caution should be observed prior to making any drastic changes in one's health and particularly the medications one takes," Gargiulo noted. "There is no 'magic bullet' and, as with most things in life, a moderate balance of work, physical exercise, spiritual enhancement and diet should be observed."
More information
The US National Heart, Lung, and Blood Institute has more about high blood pressure.
