July 10, 2000 -- Promising news for people with diabetes: high doses of vitamin E may help to prevent or reduce the severity of heart and blood vessel disease in people with type 2 diabetes, the most common form of the disease, say researchers from the University of Texas.
People with type 2 diabetes had fewer signs of atherosclerosis, or narrowing of the arteries, after taking 1,200 international units of vitamin E -- 40 times the amount currently recommended by most nutritionists -- daily for three months. Atherosclerosis, a condition that causes dangerous narrowing or blockage of blood vessels, can lead to fatal heart attacks and strokes.
Diabetes researchers have known for many years that people with both type 1 (or "juvenile-onset") diabetes and type 2 (or "adult-onset") diabetes have a much greater risk than nondiabetics for developing heart disease, high blood pressure, kidney damage, and blindness.
Because vitamin E is known to be an antioxidant -- a vitamin that helps prevent cell damage and reduce blood levels of the harmful type of cholesterol -- clinical researchers have speculated that it could help prevent or at least reduce the risk for heart disease in people with diabetes. Until recently, however, most studies using vitamin E have shown little or no beneficial effect against the complications of diabetes.
"This study was funded by the American Diabetes Association to see what high-dose vitamin E would do to diabetic patients, looking at certain markers that predispose to heart disease," says I. Jialal, MD, PhD, in an interview with WebMD.
The researchers looked for evidence of damage and inflammation of blood vessels -- early signs of atherosclerosis -- and "we showed that we had a very significant [beneficial] effect with vitamin E, but more importantly, we also showed that vitamin E had anti-inflammatory effects in the diabetic." Jialal is director of the division of clinical biochemistry and human metabolism at the University of Texas Southwestern Medical Center in Dallas.
There is a growing body of evidence to show that atherosclerosis is an inflammatory process somewhat similar to the way that a cut heals. When there is some type of damage to the walls of blood vessels -- either from high blood pressure, an infection, or an injury -- the immune system recruits repair cells and chemicals to repair the damage.
But members of the repair crew may do more harm than good, because they flock to the injury site in droves and begin to cover it over to form what is known as plaque, which is a bit like the scabs that cover skin wounds. The plaque begins to trap cholesterol, fibers, and other substances from the blood, and eventually can grow large enough to completely block the flow of blood to the heart, brain, or other vital organs.
The researchers found that in both diabetics and nondiabetics, high doses of vitamin E greatly decreased the release of damaging substances and chemicals and reduced the amount of the repair cells that stick to blood vessel walls.
And although some researchers worry that high-dose vitamin E supplements may be harmful, the researchers found no evidence of side effects throughout the three-month study.
The current study dovetails neatly with one reported by George L. King, MD, and colleagues at Harvard Medical School, which found that high-dose E is effective at preventing and may even help to reverse diabetes complications in small blood vessels within the eyes and kidneys in people with type 1 diabetes.
"The assumption here is that its only effect is as an antioxidant, but there's quite a bit of data, which we and others have shown, that vitamin E also has effects on other systems," King says, adding that what is clearly needed is a large, lengthy study of high-dose vitamin E to test this controversy.
For more information from WebMD, visit our Diseases and Conditions Diabetes page.