Vitamin E reduces high blood pressure in cases of kidney failure
kidney disease in the future, new research by the UCI College of
Medicine suggests.
High doses of vitamin E could be an important means of reducing high blood pressure, particularly in patients with kidney disease, a UCI College of Medicine study has found.
The study illustrates the key role played by oxidative stress in causing high blood pressure. It also shows how vitamin E and other antioxidants may provide new ways to treat high blood pressure.
The study appears in the wake of new research that suggests kidney disease is much more prevalent than previously assumed.
More than 300,000 people are treated for severe kidney failure in the United States every year, and this is expected to double by 2010, according to the US Public Health Service. Recent studies suggest that as many as 20 million Americans may have some degree of kidney disease, which can lead to kidney failure if not detected and treated in time.
The study, published in the January 2002 issue of Hypertension, was conducted by Dr Nick Vaziri, professor of medicine and chief of nephrology, and his team. They found that rats with impaired kidneys produced high levels of free radicals, highly reactive chemicals known to cause damage to cells and sub-cellular molecules. Antioxidants like vitamin E reduced free radical levels and eased the high blood pressure that accompanied impaired kidney function.
"This study confirms earlier work showing that kidney failure results in accelerated production of free radicals and demonstrates the beneficial effect of antioxidants," Vaziri said. "We hope that future tests on humans will show how much antioxidants can be used to help ease high blood pressure and free radical production in kidney disease."
Vaziri's team found that rats which had most of their kidneys resected to simulate kidney failure had very high blood pressure (about 197 millimeters of mercury, compared to normal readings of 110 mm). Levels of free radicals were also much higher in the kidney-resected rats. At the same time, levels of nitric oxide, a naturally occurring chemical known for its ability to relax blood vessels and for its antioxidant properties, were nearly half the levels found in rats with normal kidney function.
In addition, the team found that high doses of vitamin E raised levels of nitric oxide to nearly normal levels and lowered the high blood pressure readings by about 30 mm of mercury, bringing average pressure down to about 162 mm.
"While vitamin E clearly does not completely eliminate high blood pressure in kidney disease, it does provide partial relief and helps restore levels of nitric oxide in the body," Vaziri said. "Future research, including studies on humans, should tell us what combinations of antioxidants may be the best mix for successfully treating blood pressure."
Another UCI study on the effects of antioxidants on hospitalised patients undergoing dialysis for advanced kidney failure has been proposed for the future.
Half of kidney failure cases are caused by diabetes; the rest are caused by high blood pressure, inflammation, inherited disorders and infections. Currently, there is no cure, but early treatment and management of health issues that lead to kidney failure can help stave off the disease.
