Cardiorespiratory fitness is positively associated with both healthy and western dietary pattern in Iranian middle-aged.

Background: The association between dietary patterns and cardiorespiratory fitness (CRF) is not well established. Objective: We sought to investigate association between a posteriori dietary pattern and CRF in middle-aged adults. Design: Adults (n = 276), aged 20-74 years, who were residents of Tehran, Iran were recruited. Diet was assessed by using a validated 168-item semi-quantitative food frequency questionnaire. Principal component analysis was used to derive dietary patterns. Socio-economic status, anthropometric measures, body composition, and blood pressure were recorded. CRF was assessed by using a graded exercise treadmill test. Analysis of variance and linear regression models were used to discern the association between dietary patterns and CRF. Results: Higher scores of the healthy dietary pattern had no association with VO_2max (p = 0.13). After controlling for potential confounders, VO_2max was positively associated across tertiles of healthy dietary patterns (p < 0.001). Higher adherence to the "mixed" dietary pattern was inversely related to VO_2max (p < 0.01). After adjusting for confounders, the significant association disappeared (p = 0.14). Higher scores of the "Western" dietary pattern was not associated with VO_2max (p = 0.06). However, after controlling for potential confounders, VO_2max was positively associated with the "Western" dietary pattern (p = 0.01). A positive linear association between the "healthy" dietary pattern and CRF for the total sample (R² = 0.02; p < 0.01) were presented. Conclusions: Overall, our findings suggest that higher adherence to a "healthy" and "Western" dietary pattern was positively associated with CRF. However, further studies are required to examine and clarify the causal relationship between dietary patterns and CRF.