Relationship Between Nutritional Status and Systemic Immune–Inflammation Indices Across BMI Categories

<b>Background:</b> This study aimed to determine the relationship between nutritional status and systemic inflammation using four validated nutrition indices-Hemoglobin, Albumin, Lymphocyte, and Platelet (HALP) score, Prognostic Nutritional Index (PNI), Controlling Nutritional Status (CONUT) score, and Nutritional Risk Index (NRI)-and three immune-inflammation biomarkers-Systemic Immune-Inflammation Index (SII), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR)-in healthy adults with varying body mass index (BMI) levels. <b>Methods:</b> This retrospective study included 290 clinically healthy adults aged 18-60 years, categorized by BMI. Individuals with chronic diseases, medication use, or morbid obesity (BMI ≥ 40 kg/m²) were excluded. Nutrition scores (HALP, PNI, NRI, CONUT) and systemic immune-inflammation indices (SII, NLR, PLR) were calculated from laboratory data. For the comparisons of SII, PLR, NLR, PNI, HALP, NRI, and CONUT values between groups, age was adjusted for, and an ANCOVA test was performed. <b>Results:</b> Among the systemic immune-inflammation indices, SII and NLR were significantly higher in both the overweight and obesity groups. The CONUT score, a negative indicator of nutritional status, demonstrated positive correlations with SII, NLR, and PLR in the overweight group, and with PLR in the obesity group. Although PNI showed significant inverse correlations with SII, PLR, and NLR in both groups, the mean PNI values remained above 50, indicating overall normal nutritional status in the study population. HALP was inversely correlated with SII, PLR, and NLR in both groups. <b>Conclusions:</b> The HALP score appears to be the most reliable marker, as it reflects the inverse relationship between nutritional status and systemic immune-inflammation indices.