Introduction
Critically ill patients have considerable inflammatory response which affects metabolism and metabolic changes may occur due to different etiologies including stroke, sepsis, multiple trauma, burns, and respiratory failure. Metabolic changes are associated with systemic inflammatory response that leads to increased multi-organ failure, sepsis, immunosuppression, duration of mechanical ventilation, length of hospital stay, and higher mortality rate (1-3). Various reasons are considered for malnutrition during hospitalization including severe inflammation, increased metabolic requirements, oxidative stress, delayed or stop in enteral and parenteral nutrition for medical intervention treatment that may worsen catabolic status (4, 5). L-Carnitine (B-hydroxy- γ- trimethyl l- aminobutyric acid, LC) is an essential compound that is synthesized from lysine and methionine in the liver and kidney or its mainly supplied from animal diet sources such as meat and dairy product (6). L-Carnitine is necessary for beta-oxidation of long-chain fatty acids and fatty acid transport via Carnitine palmitoyltransferase I (CPT1) into the inner membrane of mitochondria. Therefore, L-Carnitine plays a critical role in energy metabolism (7). L-Carnitine deficiency may result in mitochondrial dysfunction and failure in lipid utilization by vital organs (8, 9). L-Carnitine deficiency leads to beta-oxidation disorder due to depletion in fatty acyl coenzyme A (CoA), which is required for lipid oxidation, and depletion of CoA enzyme pool. Therefore, mitochondrial dysfunction will occur and result in metabolic changes and multi-organ dysfunction. Oamiet al. showed that carnitine deficiency occurs in 23.4 % of critically ill patients (10). It has been shown that L-Carnitine supplementation at a dose of 1-3 gr decreases the effect of inflammation in non-communicable disease (11-13). Therefore, L-Carnitine may have the potential effect in inflammatory disease by reducing inflammatory markers, including C - reactive protein (CRP) and interlukin-6 (IL-6). To the best of our knowledge, the anti-inflammatory effect of L-Carnitine supplementation in critically ill patients was poorly investigated. In addition, there is no published study, which assessed the effects of L-Carnitine supplementation for seven days on inflammatory and clinical outcomes of the intensive care unit (ICU) patients who fed only with enteral nutrition Therefore, the purpose of this study was to evaluate the effects of L-Carnitine supplementation (with dose 3000 mg/day) on clinical status, inflammatory markers, and 28-days mortality in critically ill patients who admitted to the ICU.