The Combined Association of Dietary Inflammatory Index and Resting Metabolic Rate on Cardiorespiratory Fitness in Iranian Adults

Background: It has been shown that inflammation may be related to obesity and cardiovascular diseases. No study has examined the combined association of dietary inflammatory index (DII) of the diet and resting metabolic rate (RMR) on cardiorespiratory fitness (CRF). Therefore, we investigated the combined association between DII and RMR on CRF.Methods: This cross-sectional study was conducted on 270 adult subjects.The DII was calculated using a validated semi-quantified food frequency questionnaire. RMR was measured using an indirect calorimetric method. Socio-economic status, anthropometric measures, body composition and blood pressure were documented by a trained interviewer. CRF was assessed by using a graded exercise treadmill test. Results: Those who were classified into low DII/high RMR compared with high DII/low RMR had significant higher VO2Max (mL/kg/min) (p=0.005). Subjects in the low DII/low RMR category had significant lower VO2Max (mL/kg/min) in comparison with low DII/high RMR (p=0.001) and high DII/high RMR (p<0.001) respectively. Participants with a high DII score and low RMR had lower VO2Max (mL/kg/min) compared with those with a high DII score and high RMR (p=0.002). Moreover, we revealed that participants in the high DII/ high RMR group had lower odds of VO2max (L.min) compared with the low DII/ low RMR group which was significant. (OR: 0.93, 95% CI: 0.30, 0.38, p=0.009).Conclusions: Overall, consumption of a pro-inflammatory diet, is associated with 7% lower odds of VO2max among Iranian healthy adults. This study suggests that researchers should focus on combined relationships rather than single pair-wise associations for having a better judgment.