Study is among the first to show such an effect from a nutrient, experts say
MONDAY, June 23 (HealthDay News) -- People with heart disease and low levels of vitamin D may be at increased risk of dying from all causes and particularly from cardiovascular disease, a new study suggests.
Some 50 percent to 60 percent of older people in North America and the rest of the world have insufficient levels of vitamin D. The same is true for younger people. Low levels of vitamin D -- which can be sourced from sunlight exposure or supplements -- have been associated with falls, fractures, cancer, immune dysfunction, cardiovascular disease, and high blood pressure, researchers report. Now, a new study links insufficient vitamin D with the risk of dying.
"This is a very important study that shows low vitamin D, and low vitamin D hormone levels, are associated with cardiovascular mortality and mortality itself in a population of patients with coronary heart disease," said Robert U. Simpson, a professor in the department of pharmacology at the University of Michigan School of Medicine. He was not involved in the study.
"This study supports the current interest in raising the minimum daily requirement for vitamin D and encouraging greater surveillance of vitamin D status in the general population and specifically heart disease patients," Simpson said.
The report was published in the June 23 edition of the Archives of Internal Medicine.
In the study, Dr. Harald Dobnig, from the Medical University of Graz in Austria, and colleagues collected data on vitamin D levels among almost 3,300 patients undergoing angiography.
After more than seven years of follow-up, 737 patients had died, 463 of them from cardiovascular disease.
Dobnig's team found that death rates from any cause, and from cardiovascular disease, were higher among people with the lowest levels of vitamin D.
"Apart from the proved effects that vitamin D has on bone metabolism and neuromuscular function, appropriate serum levels are associated with a decrease in mortality," the researchers wrote.
"Although not proved, it seems possible that at least part of this effect may be due to lowering of a risk profile promoting atherosclerosis and preventing cardiovascular end points," they concluded.
Dr. Gregg C. Fonarow, a professor of cardiology at the University of California, Los Angeles, noted that similar observations with low vitamin E and beta carotene levels and cardiovascular mortality were not confirmed when vitamin supplementation was tested in clinical trials.
"Prospective randomized clinical trials of vitamin D supplementation demonstrating a reduction in cardiovascular mortality are absolutely needed before any treatment recommendations can be made," Fonarow said. "The few clinical trials of vitamin D supplementation conducted to date have been quite disappointing."
Vitamin D also appears to play a role in preventing heart failure, another study finds.
In a study, published online in Journal of Cardiovascular Pharmacology, University of Michigan pharmacologist Simpson showed that vitamin D could prevent heart failure from developing in rats.
After 13 weeks, Simpson's team found that rats prone to heart failure that received vitamin D supplements had significantly lower signs of heart failure compared with similar rats not given the nutrient.
The hearts of the treated rats weighed less and worked less well during each beat. However, blood pressure was maintained indicating that there was no reduction in heart function, according to the report.
For on vitamin D, visit MedlinePlus.
SOURCES: Robert U. Simpson, Ph.D., professor, department of pharmacology, University of Michigan School of Medicine, Ann Arbor; Gregg C. Fonarow, M.D., professor, cardiology, University of California, Los Angeles; June 23, 2008, Archives of Internal Medicine; online issue, Journal of Cardiovascular Pharmacology
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