Effect modification by dietary fiber on the association between secondhand smoke and coronary heart disease mortality among Chinese nonsmokers in Singapore

摘要

Background: Secondhand smoke (SHS) exposure increases the risk of coronary heart disease (CHD) by an estimated 25-30% via oxidative stress and inflammatory mechanisms that may be ameliorated by dietary components. Aim: We evaluated the hypothesized modifying role of nutrients with known antioxidant and/or anti-inflammatory properties on the relationship between SHS exposure and CHD mortality. Methods: Detailed SHS exposure and dietary information was collected among 29,579 nonsmokers in the Singapore Chinese Health Study, a prospective population-based cohort. The evaluation of effect modification by dietary factors (β-cryptoxanthin, lutein, n-3 PUFAs, fiber, isothiocyanates, and soy isoflavones) was conducted within multivariable Cox proportional hazards models by creating an interaction term between the potential dietary effect modifier (lowest quartile of intake vs. the second through fourth quartiles of intake) and the SHS exposure (none vs. living with ≥1 smoker[s]). Results: Evidence for a main-effects association between SHS exposure and risk of CHD mortality was not observed. In stratified analyses by levels of selected dietary nutrient intake, fiber modified the effects of SHS exposure on risk of CHD mortality (P for interaction = 0.02). The adjusted hazards ratio for SHS exposure (living with ≥1 smoker[s] vs. living with no smokers) and CHD mortality was 1.62 (95% confidence interval: 1.00, 2.63) for those with low fiber intake. In contrast, among those with high fiber intake, there was no association with SHS exposure. Conclusion: We provide the first evidence that a diet high in fiber may ameliorate the harmful effects of SHS exposure on risk of CHD mortality.