Vitamin C helps cigarette-smoking hamsters.

There's good news for antioxidant supporters: A new study in the Aug. 2 PROCEEDINGS of the NATIONAL ACADEMY Of SCIENCES shows that vitamin C protects hamsters from some of the harmful effects of cigarette smoke.

Previous studies suggested that the antioxidants vitamin C, vitamin E, and the drug probucol offer a shield against atherosclerosis -- one smoking-induced health problem -- because of their ability to disarm highly reactive free radicals in the blood (SN: 8/26/89, p.133). Data from two recent cancer prevention trials, however, have tarnished the image of antioxidants as the body's premier scavengers of harmful free radicals (SN: 7/23/94, p.54).

Certain smoking-related diseases, including atherosclerosis and emphysema, share a common trait: aggregations of leukocytes, or white blood cells, that adhere to endothelium, the smooth tissue that lines blood vessels.

Balz Frei of the Boston University School of Medicine, a coauthor of the new report, explains that "cigarette smoke is full of oxidants and free radicals," which bombard healthy DNA, wreaking havoc on normal cellular functions.

The researchers set out to see how antioxidants "can counteract cigarette-smoke-induced leukocyte activation-adhesion in the hamster." They discovered that water-soluble vitamin C, given as part of the diet or intravenously, significantly reduced white cell adhesion. Fat-soluble vitamin E and probucol had no effect on adhesion.

According to Frei, the mechanism of how cigarette smoke induces leukocyte adhesion is not well understood, though it "seems to involve a water-soluble free radical, most probably superoxide." A fat-soluble antioxidant like vitamin E may not come in contact with superoxide and therefore would not be able to detoxify this free radical.

The researchers also found that vitamin C injected just 5 minutes prior to cigarette-smoke exposure offered protection, suggesting, the authors write, "that vitamin C does not need to be incorporated into the cells in order to be effective."

William A. Pryor at Louisiana State University in Baton Rouge says he "wouldn't have predicted" vitamin E's lack of effect in these animals. Even so, both Pryor and Frei believe that antioxidants, including vitamin E, provide disease protection.

What's most important about this study, Pryor says, is the suggestion of "a biological plausibility a mechanism" to explain how antioxidants might work to prevent leukocyte adhesion. "I think this is an important paper, really provocative, very intriguing."