Association between dietary inflammatory index and sarcopenia development in Polish population

Chronic low-grade inflammation associated with nutritional deficits and physical inactivity plays a key role in development and progression of skeletal muscle diseases. The study was designed to assess the inflammatory status in relation to dietary inflammatory index (DII) in sarcopenia. One hundred twenty-one individuals aged 60-96 years were allocated into sarcopenia (n = 38), probable sarcopenia (n = 38) and non-sarcopenia (n = 45) group based on the algorithm of the European Working Group on Sarcopenia in Older People 2 (EWGSOP2). The isometric strength of hand grip was measured using a hand dynamometer KERN type MAP130 (Germany). Sarcopenia cut-off points for low muscle quantity were evaluated using the appendicular skeletal muscle mass (ASM kg) and appendicular skeletal muscle mass index (ASMI kg/m²). Meanwhile, the 6-min walk test (6MWT) was used to assess the severity of sarcopenia. In the quantitative assessment of the daily food rations, a single 24-hour dietary recall was applied. The Dietary Inflammatory Index was used to assess the Energy-adjusted Dietary Inflammatory Index (E-DII). The optimal threshold value for studied individuals corresponded to 2.283 for E-DII (AUC = 0.734, specificity 75.6%, sensitivity 70.6%, p < 0.001), which indicates an increased risk of sarcopenia with high intakes of pro-inflammatory dietary components. Furthermore, E-DII correlated with gait speed (r_s = - 0.502, p = 0.001) and the 6MWT (r_s = - 0.496, p = 0.001) thereby confirming the assumption that nutritional frailty and poor physical performance enhance sarcopenia symptomology. For E-DII and inflammatory profile models, AUC measurements for E-DII + cfDNA (cell free DNA) (AUC = 0.805) were considered a good discrimination, and the evaluation was as acceptable for cytokines interleukin 1β (IL-1β), interleukin 6 (IL-6), tumour necrosis factor α (TNFα) and C-reactive protein (CRP) (0.7 < AUC < 0.8) i.e., it enabled sarcopenia diagnosis. The analysis of E-DII with cfDNA (Classifier Accuracy 79.7%, p = 0.001) showed a higher diagnostic utility in sarcopenia prediction then conventional inflammatory markers such as IL-1β, IL-6 and TNFα, which may have important implications in defining healthy or unhealthy ageing. The results demonstrate that high intake of pro-inflammatory dietary components and low physical fitness may be one of the factors that increase the progression of sarcopenia in older adults Polish population, and simultaneously indicate a potential target for nutrition interventions to counteract the pathophysiological effects of skeletal muscle ageing.