Do cigarette smokers have diets that increase their risks of coronary heart disease and cancer?

It has been proposed that differences in diet between smokers and nonsmokers may partially explain the positive association between cigarette smoking and diseases such as cancer and coronary heart disease. To investigate the potential for this confounding, the authors studied the relation between cigarette smoking and nutrient intake in a population-based sample of 451 Australian women between 1982 and 1984. Dietary intake was determined by a quantitative food frequency questionnaire. Relations with smoking were assessed by use of analysis of covariance. The mean daily intake of total dietary fiber in current smokers was 4.1 g lower than in never smokers, with a 95% confidence interval for the difference of 1.4-6.8 g. The mean intake of total calories, cholesterol, sucrose, linoleic acid, total fat, and monounsaturated and polyunsaturated fat did not vary significantly by smoking status. However, former smokers were found to have a higher ratio of polyunsaturated to saturated fat as compared with current or never smokers and a lower intake of saturated fat as compared with current smokers. These associations persisted when the effects of total energy intake, age, years of education, and alcohol consumption were considered. The decreased ingestion of fiber by cigarette smokers could contribute to their increased risks of coronary heart disease and cancer compared with those in nonsmokers. The increased ratio of polyunsaturated to saturated fat and decreased ingestion of saturated fat in the diet of former smokers may help to reduce their risks.