Interactions Between Diet and Exposure to Secondhand Smoke on Metabolic Syndrome Among Children: NHANES 2007-2010

Context: Metabolic syndrome is likely influenced by a complex interaction between exposure to secondhand smoke (SHS) and diet, but no studies have evaluated this relationship. Objective: This study aimed to investigate the interaction between diet and exposure to SHS on metabolic syndrome among 12-19 year olds. Design and Participants: We used weighted logistic regression, adjusting for potential confounders, to examine interaction of these risk factors on the prevalence of metabolic syndrome among 12-19 year olds participating in the National Health and Nutrition Examination Survey (2007-2010). Interaction was assessed by introducing product terms between SHS (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol, cotinine, and self-report) and the individual nutrients (dietary fiber, eicosapentaenoic acid, docosahexaenoic acid, vitamin C, and vitamin E) and nutrient patterns in separate models; the relative excess risk due to interaction was used to evaluate interaction on the additive scale. Results: The joint effect between high exposure to SHS and low levels of certain nutrients (vitamin E and omega-3 polyunsaturated fatty acids) on metabolic syndrome risk was greater than would be expected from the effects of the individual exposures alone (for example, relative excess risk due to interaction for SHS and vitamin E = 7.5; 95% confidence interval, 2.5-17.8). Conclusions: Prevention strategies for metabolic syndrome aimed at reducing SHS exposures and improving diet quality may exceed the expected benefits based on targeting these risk factors separately.