A dietary shield against lung cancer?

Nonsmokers might reduce their lung cancer risk by cutting cholesterol consumption and by eating more fruits, red and yellow vegetables, and perhaps margarine, suggest three new reports in the Sept. 1 AMERICAN JOURNAL OF EPIDEMIOLOGY.

One research group followed 4,538 Finnish men for 20 years. Among the 117 men who developed lung cancer, smoking proved the biggest risk factor. But the data also suggest that nonsmokers eating diets high in antioxidants -- mainly carotenoids, vitamin C and vitamin E -- lowered their lung cancer risk by at least 60 percent. And these agents appear to act independently, since nonsmokers with diets low in all three faced nearly four times the cancer risk of those whose diets contained the most. Among plant-derived foods, fruits conveyed the biggest benefit, although the study also linked red and yellow vegetables and cereals to lower lung cancer risks.

The 2,300-plus smokers in teh group derived no antioxidant benefit, suggesting the micronutrients were not potent enough to counter smoking's influence, say Paul Knekt of the Research Institute for Social Security in Helsinki and his coauthors.

The big surprise? Nonsmokers who ate the most margarine faced only 8 percent of the lung cancer risk seen in those who ate the least margarine. Smokers also derived a benefit from margarine, but theirs was much smaller. Knekt's team speculates that margarine's effect may trace to its vitamins E content or to the possibility that men who chose it over butter took better care of themselves overall.

In another study, Richard B. Shekelle of the University of Texas at Houston and his colleagues reviewed dietary data on 1,878 Chicago men employed by the Western Electric Co. in 1958. During a 24-year follow-up, 57 died of lung cancer. After adjusting for age, smoking and consumption of fat and betacarotene (a carotenoid), the researchers found that men who had ingested more than 795 milligrams of cholesterol daily ran nearly double the lung cancer risk of those eating less than 605 mg/day. However, this association "was specific to consumption of eggs," the researcher write. Chance, or perhaps a noncholesterol ingredient in eggs, may explain the egg/cancer correlation, they say. But they also note that three other studies have found hints of a cholesterol link to lung cancer.

Marc T. Goodman of the Cancer Research Center of Hawaii in Honolulu, who coauthored one of three previous studies, has now reanalyzed a portion of his data. While a cholesterol-cancer link remained, there was "no evidence of a dose-response relation between egg consumption and the risk of lung cancer," he writes in a letter published in the same journal. He notes, however, that the Chicago men consumed far more eggs and cholesterol than did the Hawaiians in his own study.