Commentary: Physical fitness: confounder or intermediary variable in the association of diet with health outcomes?

Abstract

Index. 2 Individuals in the highest compared with the lowest quintile of the distribution of the Unhealthy Eating Index had a 1.40-fold increased risk [95% confidence interval (CI) 1.02–1.91] of allcause mortality after adjustment for age, gender, year of examination, parental history of CVD, history of CVD, history of cancer, smoking and alcohol consumption. Further adjustment for physical activity (assessed through self-report by questionnaire about the participant’s physical activity patterns over the preceding 3 months) had little effect on the relationship between the Unhealthy Eating Index and allcause mortality (relative risk in the highest vs lowest quintile, 1.36; 95% CI 0.99–1.87). In contrast, adjustment for physical fitness (as assessed through a symptom-limited maximal exercise treadmill test) substantially attenuated the relationship (relative risk, 1.18; 95% CI 0.86–1.64).