Micronutrients and ICU-Acquired Weakness: A Narrative Review

Intensive Care Unit-Acquired Weakness (ICU-AW) is a secondary neuromuscular disorder diagnosed during a critical illness and related to ICU stay and intensive treatments, once other possible etiologies have been excluded. Micronutrients are essential components of human nutrition that are needed in small amounts to maintain pivotal organ functions, but their role in critical care nutrition and in prevention and treatment of ICU-AW is unclear. This narrative review aimed to provide a synthesis of the current evidence on the potential role of micronutrients in ICU-AW, with a glance at what is known in medical settings outside the ICU. Available evidence is fragmented, showing controversial results. Studies on vitamin K1 and vitamin D suggest potential benefits on handgrip strength, skeletal muscle mass and mobility, while Coenzyme Q10 may have a role in improving skeletal muscle composition. Moreover, zinc homeostasis may influence muscle degradation, whereas copper levels may represent a risk factor. Evidence on iron and carnitine showed uncertain results. Conversely, more robust evidence on muscle weakness is available for medical settings outside the ICU. Larger observational studies and RCTs are needed to further evaluate the possible efficacy of micronutrient supplementation in the critical care setting.