Fruits And Vegetables May Help Reduce Risk Of Stroke

Damaging Effects In Cells Reduced

Higher blood levels of carotenoids, antioxidants found in fruits and vegetables, may reduce the risk of ischemic stroke, according to a study reported in the medical journal Stroke.

Ischemic stroke occurs when a blood vessel that supplies the brain becomes blocked or "clogged" and impairs blood flow to part of the brain.

The risk of ischemic stroke was 40 percent lower in men with the highest blood levels of carotenoids than in those with the lowest levels, the researchers say.

Antioxidants protect key cell components by neutralizing the damaging effects of "free radicals," natural byproducts of cell metabolism.

Carotenoids are molecules that the body converts into vitamin A. They help provide the vivid coloring of carrots, peaches, watermelon, and other fruits and vegetables. They are also popular ingredients in vitamin supplements.

Link Between Stroke and Antioxidants

The report came from the Physicians' Health Study, which has followed more than 22,000 male physicians since 1982. It covers a 13-year period, in which 297 of the physicians had ischemic strokes.

The researchers measured blood levels of a variety of antioxidants in blood samples given by the participants when the study started. They found the higher risk in men with the lowest levels of three carotenoids: alpha-carotene, beta-carotene, and lycopene.

The study was not designed to determine the source of the carotenoids, said study author Dr. Jing Ma, an assistant professor of medicine at Harvard Medical School.

But they "most likely came from food," Dr. Ma adds. "At the time the study began, the participants were asked not to take supplements, so we most likely measured what came from fruits and vegetables."

It is not possible to say whether the carotenoids themselves were responsible for any protective effect, since "there are so many other good nutrients from fruits and vegetables other than the ones we measured," she says.

And the evidence that carotenoids in general are good for the arteries is not clear, Dr. Ma says.

A recent report from the Physicians' Health Study found no relationship between carotenoid levels and risk of heart attack, she notes.

The long-term goal of the study is to help determine the role that antioxidants play in prevention of heart attack, stroke, and other cardiovascular diseases, Dr. Ma says.

"In a few years, we should have more definite conclusions from this study," she adds.

Food Vs. Supplements

Meanwhile, the current results support the American Heart Association position that "diet should be the source of antioxidants and not supplements," said Dr. Robert H. Eckel, a professor of physiology and biophysics at the University of Colorado Health Sciences Center.

"The evidence to support the value of supplements is just not available," Dr. Eckel says. "It is what we eat rather than what we supplement that is important."

An excellent way to choose antioxidant-rich fruits and vegetables is to go by color, Dr. Eckel says. "Colorful vegetables are where we expect a higher content," he explained, "sweet potatoes and spinach, apricots, carrots, things with an orange or yellow color."

Always consult your physician for more information.

Online Resources

American Heart Association

July 2004

Fruits And Vegetables May Help Reduce Risk Of Stroke

Link Between Stroke and Antioxidants

Food Vs. Supplements

Antioxidants Explained

Online Resources

Antioxidants Explained

The American Heart Association (AHA) recognizes that research has recently focused on how antioxidant vitamins may reduce cardiovascular disease risk.

Antioxidant vitamins - E, C, and beta carotene (a form of vitamin A) - have potential health-promoting properties.

About 30 percent of US adults are taking some form of antioxidant supplement, the AHA estimates.

However, the AHA does not recommend using antioxidant vitamin supplements until studies provide more complete information.

Instead it recommends that people eat a variety of foods daily from all the basic food groups:

• six or more servings of breads, cereals, pasta, and starchy vegetables
  
  
• five servings of fruits and vegetables
  
  
• two to four servings of fat-free milk, low-fat dairy products
  
  
• up to six cooked ounces of lean meat, fish, poultry
  

Eating a variety of foods low in saturated fat and cholesterol will provide a rich natural source of these vitamins, minerals, and fiber.

Oxidation of low-density lipoprotein (LDL or "bad") cholesterol is important in the development of fatty buildups in the arteries.

This process, called atherosclerosis, can lead to heart attacks and strokes.

Increasing evidence suggests that LDL cholesterol lipoprotein oxidation and its biological effects can be prevented by using antioxidants - both in the diet and in supplements.

The strongest evidence for using naturally occurring antioxidants to protect against the development of cardiovascular disease is for vitamin E. The evidence is weakest for vitamin C. Research on the role of beta carotene is inconclusive.

High intake of vitamin E has been associated with a lower risk of coronary artery disease (CAD) incidence, based on some studies.

Animal studies also suggest that vitamin E can slow the development of atherosclerosis.

Further, vitamin E inhibits LDL cholesterol oxidation in test tube experiments and in human studies.

Some other studies suggest that vitamin C, which also inhibits lipoprotein oxidation, is associated with reduced rates of clinical CAD.

Beta carotene does not seem to inhibit LDL cholesterol oxidation, but early research suggests that it may reduce further clinical events in people who have CAD.

Using dietary supplements of antioxidants to prevent cardiovascular disease should not be recommended until their effect is proved in clinical trials that directly test their impact on CAD end points, the AHA urges.

This caution is necessary because the doses of these antioxidants that inhibited LDL cholesterol oxidation in some studies are much larger than can be achieved by diet alone.

Always consult your physician for more information.