(Posted 6-02-00)
IMMEDIATE RELEASE
News Service Contact: Laurie Gengenbach, 336-334-5371
UNCG RESEARCH INDICATES VITAMINS C
AND E DO NOT PREVENT OXIDATION IN SMOKERS
GREENSBORO - A new study by Dr. Cindy Fuller, assistant professor of nutrition at The University of North Carolina at Greensboro, gives smokers another reason to kick the habit.
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Although many people take supplements of vitamins C and E as antioxidants, her research casts doubt on their effectiveness in cigarette smokers. Vitamin E increased the time it took for LDL (low density lipoprotein) to oxidize, but vitamin C had no effect. More physiologically relevant measures of superoxide production by white blood cells showed no change with any treatment.
It is commonly believed that oxidation of lipids contributes to the development of heart disease, aging, cancer, and other chronic illnesses. Other studies have substantiated the effectiveness of vitamins E and C in reducing oxidation in non-smokers. Fuller's study was unique in that it tested the ability of commonly taken antioxidant vitamins to inhibit oxidation in young adults with a mean age of 20 years who had been smoking for an average of only two and a half years.
Dietary antioxidants are nutrients that help protect cells from a normal -- but damaging -- physiological process known as "oxidative stress." Such nutrients are a part of the natural makeup of many types of food, particularly fruits and vegetables. They also have been added to some foods and are available in the form of dietary supplements. For years, researchers have sought to understand the role of these antioxidants in reducing the risk of chronic diseases such as cancer, cardiovascular disease, eye diseases, and neurodegenerative diseases, which include Alzheimer's and Parkinson's. But many unanswered questions remain.
In Fuller's study, 30 smokers were randomly assigned to take vitamin
C (1000 mg/day), vitamin E (400 IU/day), both vitamins, or a placebo for
eight weeks in a double-blind fashion where neither the subjects nor the
researchers knew which pills were being taken. The research was published
in the June issue of the "Journal of the American College of Nutrition."
Supplementation increased blood levels of the vitamins, as expected.
Subjects who received vitamin E had a 64% increase in the time it took
for their LDL in a test tube to become oxidized by the addition of copper.
There were no changes in the groups given vitamin C or placebo. The group
receiving both vitamins showed no increase in time to oxidation but did
decrease their maximal rate of oxidation significantly by 31%
.
In contrast, two separate measures of oxidation by white blood cells,
thought to be more reflective of what happens in the body, showed no changes
as a result of any of the antioxidant treatments.
Supplementation with vitamin E caused significant drops in carotenoids in the LDL, which are also thought to prevent against oxidation. Both beta-carotene and lycopene decreased significantly at eight weeks.
"These results cast doubt on the ability of antioxidant supplements to reduce oxidative stress in smokers," Fuller said. "Even in young smokers who had relatively short histories of smoking, there was minimal beneficial effect detected. Therefore, smoking cessation remains the only means by which young smokers can prevent heart disease."
"This is really relevant to young folks who don't think smoking can't harm them if they just take these pills," added David Klurfeld, editor in chief of the "Journal of the American College of Nutrition." "A lot of people think if they take pills, they can make up for various sins. This is one that the pills don't make up for."
Fuller, an assistant professor of nutrition, joined the UNCG faculty in 1995. Her research focuses on antioxidants and health. She received her doctorate from Cornell University.