Nutritional Support Strategies in Critical Care

Critically ill patients are particularly vulnerable to malnutrition due to hypermetabolism, systemic inflammation and impaired gastrointestinal function. Nutritional support aims to preserve lean body mass, modulate immune responses and prevent complications associated with both underfeeding and overfeeding. Enteral nutrition via the gastrointestinal tract is the preferred route and should be initiated early in the absence of contra­indications, advancing progressively towards individualised energy and protein targets. When enteral access is not feasible or fails to meet requirements, supplemental parenteral nutrition can be introduced to avoid cumulative deficits. Energy expenditure is optimally assessed through indirect calorimetry, while protein delivery is often guided by weight-based targets and phase of illness. Monitoring of feeding tolerance and gastrointestinal dysfunction is essential to adapt strategies, minimise the risk of refeeding syndrome and ensure adequate substrate delivery. Emerging approaches include the exploration of alternative substrates such as ketone bodies to address bioenergetic failure. Personalised feeding regimens that integrate metabolic monitoring, risk stratification and phased nutritional goals are now central to improving outcomes in the intensive care setting.

Research from Nature Portfolio

Recent pilot trials have demonstrated the feasibility and safety of inducing nutritional ketosis in mechanically ventilated patients with multi‐organ failure. A two-centre open-label study achieved sustained ketosis through a ketogenic enteral formula, recording fewer hypoglycaemic events, reduced insulin requirements and acceptable gastrointestinal tolerance. These findings support the concept that alternative substrates may ameliorate bioenergetic deficits in critical illness and pave the way for larger trials evaluating functional and survival endpoints.

Nutritional Support Strategies in Critical Care publication trend

The graph below shows the total number of articles in nutritional support strategies in critical care across all publications each year (not limited to Nature Index journals).

Technical terms

Enteral nutrition: Delivery of nutrients directly into the gastrointestinal tract via nasogastric, nasojejunal or percutaneous feeding tubes.

Parenteral nutrition: Intravenous infusion of macronutrients and micronutrients when enteral feeding is contraindicated or insufficient.

Indirect calorimetry: Technique to measure resting energy expenditure by analysing inspired and expired gas exchange.

Ketogenic feeding: Nutritional regimen high in fats and low in carbohydrates designed to induce and maintain ketosis.

Bioenergetic failure: Impaired cellular energy production contributing to organ dysfunction in critical illness.

Refeeding hypophosphataemia: Rapid shifts of phosphate into cells upon reintroduction of nutrition, risking neuromuscular and cardiac complications.

References

1. A pilot study of alternative substrates in the critically Ill subject using a ketogenic feed. Nature Communications (2023).
2. Nine Myths about Enteral Feeding in Critically Ill Adults: An Expert Perspective. Advances in Nutrition (2024).
3. Early protein delivery in critically ill patients with acute kidney injury: post hoc analysis of a multicenter cluster-randomized controlled trial. Burns & Trauma (2024).
4. Nutrition therapy and critical illness: practical guidance for the ICU, post-ICU, and long-term convalescence phases. Critical Care (2019).