# Fish Oil-Containing Injectable Lipid Emulsions in Parenteral Nutrition: Immunomodulation and Clinical Outcomes in Critically Ill Patients—Narrative Review

## TL;DR

Injectable lipid emulsions with fish oil may improve outcomes in critically ill patients by reducing inflammation and infection risks.

## Contribution

This review highlights the clinical benefits of fish oil-containing lipid emulsions in critical care through their immunomodulatory effects.

## Key findings

- Fish oil emulsions may reduce infection and sepsis risks in critically ill patients.
- They can shorten ICU stays and improve outcomes in acute pancreatitis.
- Omega-3 emulsions may lower delirium and gastric emptying issues.

## Abstract

Background and Aims: Injectable lipid emulsions are an integral component of parenteral nutrition, providing energy as well as essential fatty acids. However, conventional soybean oil–based emulsions, which are rich in omega-6 fatty acids, are associated with a risk of exacerbating pro-inflammatory responses and immunosuppression, which is of particular importance in critically ill patients. The aim of this review is to present the significance of the composition of modern injectable lipid emulsions, with particular emphasis on emulsions containing fish oil as a source of omega-3 fatty acids (EPA and DHA), and to discuss their potential clinical benefits in selected critical conditions. Methods: This narrative review discusses the rationale for modern mixed-oil ILE, with a focus on fish oil as a source of EPA and DHA, and summarizes potential clinical benefits in selected critical care settings. Results: Modern injectable lipid emulsions combine long-chain triglycerides derived from soybean oil (omega-6), MCTs, olive oil (omega-9), and fish oil (omega-3). Adjusting the supply of individual fractions affects cell membrane structure, signaling pathways, gene expression, and the profile of lipid mediators produced, including specialized pro-resolving mediators (SPMs). ESPEN guidelines and international recommendations emphasize the need to use lipids in parenteral nutrition, preferring mixed-oil ILE supplemented with fish oil. The cited meta-analyses and clinical studies indicate that omega-3-containing emulsions may reduce the risk of infections and sepsis; shorten hospital stay, ICU length of stay, and duration of mechanical ventilation in patients with sepsis; as well as improve outcomes in acute pancreatitis; lower the risk of delirium; and reduce the incidence of delayed gastric emptying. Conclusions: Available data support the use of mixed-oil ILE supplemented with fish oil in the parenteral nutrition of critically ill patients as a strategy with immunomodulatory and pro-resolving potential that may translate into improved clinical outcomes. However, further well-designed randomized trials are needed to optimize dosing and administration regimens.