Association of dietary total antioxidant capacity, dietary inflammatory index, and dietary phytochemical index with sarcopenia in middle-aged and older Iranian women: a case-control study

As life expectancy increases worldwide, the older population and age-related diseases such as sarcopenia are increasing. Although some studies have examined the effects of inflammation or antioxidants on muscle health, evidence in this area remains limited. Given the impact of diet on muscle health, this study investigated the relationship between the Dietary Inflammatory Index (DII), Dietary total Antioxidant Capacity (DTAC), and Dietary Phytochemical Index (DPI) with sarcopenia in middle-aged and older Iranian women. In this case-control study, a total of 120 participants (60 cases and 60 controls), frequency-matched case-control study (by age and physical activity), were studied. Body composition was assessed using bioelectrical impedance analysis (BIA), and gait speed and handgrip strength were assessed for all participants. Sarcopenia was identified according to the Asian Working Group on Sarcopenia (AWGS) criteria. Dietary intake was assessed using a validated 168-item semi-quantitative food frequency questionnaire (FFQ), and DII, DTAC, and DPI scores were calculated. Multivariate logistic regression was used to determine the associations, with p < 0.05 considered statistically significant. In the adjusted models, higher DTAC was associated with lower odds of sarcopenia (OR = 0.744; 95% CI = 0.588–0.942), while higher DII was associated with increased odds (OR = 2.35; 95% CI = 1.51–3.63). DPI also remained significantly associated with lower odds (OR = 0.516; 95% CI = 0.322–0.828). In conclusion, an inflammatory diet was associated with higher odds of sarcopenia, while diets rich in antioxidants and phytochemicals were associated with lower odds.