Diabetes Forecast June 2005

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FOR TYPE 2

Research Profile

Vitamins C And E
Protection For Your Blood Vessels?
by Terri Kordella

David S. Schade, MD, left, and third-year medical student Absalon Gutierrez believe the vascular protection offered by vitamins C and E may depend on how much you take.	David S. Schade, MD Occupation Professor of Medicine University of New Mexico Health Sciences Center Professional Focus Type 2 diabetes Outside Interests Bridge, horses, raising beef cattle Research Funding ADA Clinical Research Award

David S. Schade, MD, is looking out for your heart—and your wallet.

In a time when pharmacists' shelves are filled with prescription drugs designed to help you prevent atherosclerosis (hardening of the arteries), he's investigating the protective benefits of two over-the-counter pills you probably already have in your medicine cabinet or kitchen cupboard: vitamin C and vitamin E.

"Vitamins C and E are traditionally thought of as antioxidants," says Schade, professor of medicine at the University of New Mexico Health Sciences Center. "These two vitamins in particular seem to protect the body from oxidative stress caused by the foods we eat. Any cheap and effective treatment, I'm for."

Oxidative stress occurs when your body metabolizes the food you eat and generates molecules called oxygen free radicals. These free radicals combine with other substances in your bloodstream such as LDL cholesterol and damage the walls of your blood vessels. This, in turn, can cause inflammation and clotting in the blood vessels and set you up for heart disease and stroke.

The effectiveness of vitamins C and E at fighting oxidative stress is a subject of controversy, however.

"There were large clinical trials that tested vitamins C and E in people to see if they prevented atherosclerosis over time, but only a few of them concluded that these vitamins had a protective effect," says Schade.

He feels the results varied among the large studies in part because the doses were inconsistent from study to study. It occurred to him that maybe the participants in the trials that showed no protective benefits simply weren't taking enough of the vitamins. The first step should have been to determine an effective dose in a smaller population, he says.

"Before doing these large clinical trials, you should know how much to take," Schade says. "We think they put the cart before the horse."

So, with funding from an American Diabetes Association Clinical Research Award, Schade and third-year medical student Absalon Gutierrez will study the effects of different doses in 20 to 30 adults with type 2 diabetes. They are studying this population because people with type 2 are at high risk for developing atherosclerosis and its associated heart trouble.

Finding The Right Dose

Schade's team will study the effects of three different dose combinations of vitamins C and E. The three dose combinations are 1,000 mg of vitamin C and 800 IU of vitamin E; 500 mg of vitamin C and 400 IU of vitamin E; and 250 mg of vitamin C and 200 IU of vitamin E.

Each participant will complete the study in four 2-week rounds. For each round, the participant will take either placebo or one of the vitamin combinations. Neither the researchers nor the participant will know what the participant is taking for each round, but all participants will eventually take every vitamin combination and a round of placebo.

At the end of each round, the participant will come to the research center for an overnight stay and a test meal. The test meal—a burger, fries, and a shake—is a dietary nightmare high in saturated fat, but that's why Schade's team is using it. Saturated fat is known to cause significant oxidative stress, so the meal will provide an indication of how well the pills work.

After the meal, the participant will undergo a blood test once every 30 to 60 minutes for 6 hours. The researchers will measure markers (indicators) of oxidative stress in the participant's blood. Such markers include c-reactive protein, which indicates inflammation in the arteries, and fibrinogen, which indicates a clotting reaction in the arteries.

After the participants have completed the study, the research team will learn the order in which the participants took the pills and go back and compare the results of all the blood tests. That's when the team will discover the answer to the all-important question: Which dose combination resulted in the fewest markers of oxidative stress in the participants' bloodstreams after the test meals? The next step, then, would be to test that dose in a larger trial.

The implications of Schade's research could be far-reaching for people with diabetes. Heart disease caused by atherosclerosis is the most common complication of diabetes and the number one killer of people with type 2. A common complication calls for common prevention, if at all possible, he says.

"We became interested in these vitamins because they are inexpensive, they don't require a prescription, and people take them all the time," he says. "I'm not saying that you can take a vitamin and then eat anything, but the reality is that people do eat unhealthy food. I'm in favor of any cheap and safe way we can help them protect themselves from the effects of it."