Nutrition

Nutrition in Critical Care: 2026 Evidence & Management

Current standard of care for nutrition in the critically ill — when and how to feed, energy and protein targets, parenteral nutrition, and glucose control — organized by decision, with the trials behind each recommendation.

Reviewed by the DosePilot Medical Team · Last reviewed: Jun 2026 · Independent — no industry funding
How to read this page. Each decision opens with the current approach, then the trials behind it (design, key results, limitations), and a short practical note (In practice). All targets, doses, and figures are taken from the cited primary sources (DOI + PMID). The modern theme is restraint in the acute phase — feed enterally, start modestly, and avoid pushing full calories and high protein early — then escalate as the patient recovers. The ASPEN/SCCM (2016) and ESPEN (2023) ICU guidelines anchor the recommendations. In practice notes are general guidance, not a substitute for clinical judgment.
How we verify evidence & editorial policy
Written and maintained by the DosePilot Medical Team. Recommendations are based on randomized controlled trials and current society guidelines (GRADE). Every citation is verified directly against PubMed (PMID) and the publisher DOI — no memory-based or AI-generated references. Each topic is peer-reviewed by the clinical team before publication and re-reviewed at least every 12 months or when major new evidence appears.

Funding & conflicts of interest. Produced independently; no industry funding was received for this content and contributors report no relevant financial conflicts of interest.
On this page
  1. Evidence timeline
  2. When & how to start — route and timing
  3. Energy targets — how much, and when
  4. Protein targets
  5. Parenteral & supplemental nutrition
  6. Glycemic control
  7. Refeeding syndrome
  8. GI intolerance & delivery
  9. Special populations & micronutrients
  10. Monitoring & the recovery transition
  11. Where it’s heading
  12. Bottom line
  13. FAQ
  14. Related DosePilot tools
  15. Guidelines & evidence basis
At a glance — current standard of care
DecisionCurrent approachKey trial(s)
RouteEnteral first, start within 24–48 hASPEN; ESPEN
Energy (acute phase)Don’t aim for full early — modest/hypocaloric is safeEDEN; TARGET; PermiT
Protein~1.2–1.3 g/kg/day; higher gives no benefitEFFORT; PRECISe
Parenteral nutritionOnly if EN insufficient — don’t start earlyEPaNIC; CALORIES
GlucoseTarget 140–180 mg/dL (avoid tight control)NICE-SUGAR
Safety / specialCurrent approachKey source(s)
ShockEarly low-calorie/protein EN; PN no betterNUTRIREA-2; NUTRIREA-3
Refeeding riskRestrict calories; replace phosphate, K, Mg; thiamineDoig 2015
GlutamineDo not give routinely (harm in organ failure)REDOXS
GI intoleranceDon’t stop for high residual alone; prokineticsguidelines
Energy estimateIndirect calorimetry preferred to equationsESPEN

1Evidence timeline (2009–2026)

2009NICE-SUGAR — tight glucose control (81–108 mg/dL) increases mortality versus a target under 180; sets the modern glucose range
2011EPaNIC — starting parenteral nutrition early (day 1–2) to supplement enteral feeding causes more complications and slower recovery than waiting to day 8
2012EDEN — in acute lung injury, trophic (low-volume) enteral feeding for 6 days is as good as full feeding, with less GI intolerance
2013REDOXS — high-dose glutamine (and antioxidants) in multi-organ failure is harmful, increasing mortality
2014CALORIES — the route (parenteral vs enteral) does not change mortality when calories are matched; enteral remains first-line on safety/cost
2015PermiT — permissive underfeeding (40–60% of target calories, protein similar in both groups) gives the same outcomes as standard feeding
2018TARGET — energy-dense feeding (more calories) does not improve survival; NUTRIREA-2 — in shock, early enteral nutrition gives more GI complications than parenteral, with no mortality benefit
2023NUTRIREA-3 — in shock, early low calorie/protein feeding speeds recovery versus standard targets; EFFORT Protein — high protein (≥2.2 g/kg) confers no benefit and may harm the sickest and those with kidney injury
2024PRECISe — higher protein does not improve functional recovery, reinforcing a moderate protein target
2025–26Personalized nutrition (indirect calorimetry, recovery-phase protein and rehabilitation) is the research frontier — but no trial has shown that feeding more, earlier helps; the acute-phase default stays conservative

2When & how to start — route and timing

Current approach (2026)
Enteral firstStart ≤24–48 h
For the patient who cannot eat, use the gut: start enteral nutrition (EN) within 24–48 hours of ICU admission once resuscitated, and prefer EN over parenteral nutrition (PN) — EN is cheaper, preserves gut integrity, and avoids the line and overfeeding risks of PN, while the landmark CALORIES trial shows the route itself does not change survival. Begin at a modest rate rather than racing to goal (Section 3). In shock, EN is not contraindicated but should be low-volume and cautious — full-dose early EN causes more bowel complications without benefit (NUTRIREA-2). Reserve PN for when EN is impossible or insufficient, and do not start it early (Section 5). Screen nutritional risk early, but remember no score has been shown to identify who benefits from aggressive feeding.
Evidence — old → new
2014
CALORIES. 2400 critically ill adults randomized to early PN vs early EN. 30-day mortality was identical (33.1% vs 34.2%), with no difference in infections; the PN group had less hypoglycemia and vomiting. The route is not what matters — caloric delivery and avoiding overfeeding are. EN stays first-line on safety and cost.
2018
NUTRIREA-2. 2410 ventilated adults in shock randomized to early isocaloric EN vs PN. No mortality difference (37% vs 35%), but early full EN caused more vomiting, diarrhea, bowel ischemia, and pseudo-obstruction. In shock, feed the gut gently — don’t push full-volume EN.
2023
NUTRIREA-3. 3044 ventilated adults in shock randomized to early low (6 kcal/kg, 0.2–0.4 g/kg protein) vs standard (25 kcal/kg, 1.0–1.3 g/kg) calorie/protein for the first 7 days. The low-intake group was ready for ICU discharge sooner, with less vomiting, diarrhea, and hyperglycemia and no increase in mortality — confirming that less is more in the acute phase of shock.

What changed. “Feed early and aggressively” gave way to “use the gut, but gently.” Enteral access and early initiation are still the default, but the goal of the first days is tolerance and avoiding harm, not hitting a calorie number.

In practice

Once the patient is resuscitated, start EN within 24–48 h at a low rate and advance as tolerated. Don’t withhold EN for vasopressors alone, but in deepening shock keep it trophic and watch for distension or rising lactate. Choose PN only when the gut cannot be used — and not in the first week.

Sources (4)
  • Harvey SE, Parrott F, Harrison DA, et al; CALORIES Trial Investigators. Trial of the route of early nutritional support in critically ill adults (CALORIES). N Engl J Med. 2014;371(18):1673–1684. DOI 10.1056/NEJMoa1409860. PMID 25271389.
  • Reignier J, Boisramé-Helms J, Brisard L, et al; NUTRIREA-2 Trial Investigators, Clinical Research in Intensive Care and Sepsis (CRICS) group. Enteral versus parenteral early nutrition in ventilated adults with shock (NUTRIREA-2). Lancet. 2018;391(10116):133–143. DOI 10.1016/S0140-6736(17)32146-3. PMID 29128300.
  • Reignier J, et al; NUTRIREA-3 Trial Investigators, CRICS-TRIGGERSEP Group. Low versus standard calorie and protein feeding in ventilated adults with shock (NUTRIREA-3). Lancet Respir Med. 2023;11(7):602–612. DOI 10.1016/S2213-2600(23)00092-9. PMID 36958363.
  • McClave SA, Taylor BE, Martindale RG, et al. Guidelines for the provision and assessment of nutrition support therapy in the adult critically ill patient (SCCM/ASPEN). JPEN J Parenter Enteral Nutr. 2016;40(2):159–211. DOI 10.1177/0148607115621863. PMID 26773077.

3Energy targets — how much, and when

Current approach (2026)
Full early feeding: no benefitUnderfeeding is safe
In the acute phase (roughly the first week), do not aim for full caloric targets. Multiple large trials show that delivering more calories early — whether by full EN (EDEN), energy-dense formula (TARGET), or supplemental PN (EPaNIC) — does not improve survival, ventilator-free days, or recovery, and may add harm (hyperglycemia, overfeeding, infection). A reasonable practical target is to stay hypocaloric early (around or below 70% of estimated needs when using predictive equations) and build toward goal over the first week, with adequate protein maintained. Use indirect calorimetry to set energy needs when available (predictive equations such as 25 kcal/kg are imprecise) and avoid both under- and over-feeding once the recovery phase begins.
Evidence — old → new
2012
EDEN. 1000 patients with acute lung injury randomized to trophic (~400 kcal/day) vs full (~1300 kcal/day) EN for 6 days. No difference in ventilator-free days, 60-day mortality, or infections; trophic feeding had less GI intolerance. Showed that near-starvation early is not harmful in this population.
2015
PermiT. 894 adults randomized to permissive underfeeding (40–60% of calculated calories) vs standard (70–100%), with protein targeted equally in both groups (achieved protein was only ~0.8 g/kg/day in both arms — below current targets). No difference in 90-day mortality or any secondary outcome — isolating the calorie effect and confirming that fewer calories is safe (it does not prove low calories plus full protein).
2018
TARGET. 3957 ventilated patients randomized to energy-dense (1.5 kcal/mL) vs routine (1.0 kcal/mL) EN. Despite ~600 more kcal/day, 90-day mortality was identical (relative risk 1.05; 95% CI 0.94–1.16). More calories did not help — and raised insulin needs.

What changed. The field abandoned aggressive early calorie targets. The consistent signal across EDEN, PermiT, and TARGET is that the critically ill tolerate — and are not harmed by — receiving fewer calories in the acute phase, so the burden of proof now sits with feeding more.

In practice

Don’t chase 100% of calories in the first days; advance toward target over the first week and lean lower in shock or refeeding risk. Set needs by indirect calorimetry where possible, keep protein adequate, and escalate energy as the patient stabilizes and begins to recover.

Sources (3)
  • Rice TW, Wheeler AP, Thompson BT, et al; NHLBI ARDS Clinical Trials Network. Initial trophic vs full enteral feeding in patients with acute lung injury: the EDEN randomized trial. JAMA. 2012;307(8):795–803. DOI 10.1001/jama.2012.137. PMID 22307571.
  • Arabi YM, Aldawood AS, Haddad SH, et al; PermiT Trial Group. Permissive underfeeding or standard enteral feeding in critically ill adults. N Engl J Med. 2015;372(25):2398–2408. DOI 10.1056/NEJMoa1502826. PMID 25992505.
  • TARGET Investigators, ANZICS Clinical Trials Group; Chapman M, Peake SL, Bellomo R, et al. Energy-dense versus routine enteral nutrition in the critically ill. N Engl J Med. 2018;379(19):1823–1834. DOI 10.1056/NEJMoa1811687. PMID 30346225.

4Protein targets

Current approach (2026)
High protein: no benefitPossible harm in AKI/sickest
Target a moderate protein intake of ~1.2–1.3 g/kg/day (guidelines historically suggested up to 1.5–2.0, but recent randomized data do not support pushing high). The large EFFORT Protein trial found that high protein (≥2.2 g/kg/day) did not improve survival or time-to-discharge, and signaled harm in the sickest patients and those with acute kidney injury. PRECISe likewise found no functional-recovery benefit from higher protein. Deliver protein steadily even while calories are kept modest, and be especially cautious about high protein loads in AKI not yet on dialysis and in early shock.
Evidence — old → new
2023
EFFORT Protein. 1301 high-risk critically ill adults randomized to high (≥2.2 g/kg/day) vs usual (≤1.2 g/kg/day) protein. No difference in time-to-discharge-alive or 60-day mortality; a prespecified analysis suggested worse outcomes with high protein in patients with baseline AKI and higher organ-failure scores. Reversed the long-standing “more protein is better” assumption.
2024
PRECISe. Randomized higher vs standard protein and measured functional recovery (health-related quality of life). Higher protein did not improve — and slightly worsened — functional outcomes, supporting a moderate target and shifting attention from “how much protein” to rehabilitation and the recovery phase.

What changed. Protein was the last refuge of “more is better” after the calorie trials; EFFORT and PRECISe closed that door too. The acute-phase target settled near 1.2–1.3 g/kg/day, with genuine caution about high loads in kidney injury.

In practice

Aim for ~1.2–1.3 g/kg/day and don’t reflexively escalate to 2 g/kg. In AKI (especially pre-dialysis) and the sickest patients, keep protein moderate. Maintain protein even when restricting calories, and revisit higher intakes only in the recovery/rehabilitation phase if at all.

Sources (3)
  • Heyland DK, Patel J, Compher C, et al; EFFORT Protein Trial Collaborators. The effect of higher protein dosing in critically ill patients with high nutritional risk (EFFORT Protein): an international, multicentre, pragmatic, registry-based randomised trial. Lancet. 2023;401(10376):568–576. DOI 10.1016/S0140-6736(22)02469-2. PMID 36708732.
  • Bels JLM, Thiessen S, van Gassel RJJ, et al; PRECISe study team. Effect of high versus standard protein provision on functional recovery in people with critical illness (PRECISe). Lancet. 2024;404(10453):659–669. DOI 10.1016/S0140-6736(24)01304-7. PMID 39153816.
  • Singer P, Blaser AR, Berger MM, et al. ESPEN practical and partially revised guideline: clinical nutrition in the intensive care unit. Clin Nutr. 2023;42(9):1671–1689. DOI 10.1016/j.clnu.2023.07.011. PMID 37517372.

5Parenteral & supplemental nutrition

Current approach (2026)
Early PN: more complicationsUse when EN insufficient
Reserve parenteral nutrition (PN) for patients in whom enteral feeding is impossible or persistently insufficient — and do not start it early. The landmark EPaNIC trial showed that adding PN on day 1–2 to reach calorie targets caused more infections, longer ventilation and ICU stay, and slower recovery than withholding PN until day 8. When EN is failing, the timing of supplemental PN is a judgment call: most guidelines suggest waiting until day 4–7 before adding PN to close a persistent caloric gap, individualized by nutritional risk. When PN is used, avoid overfeeding (it drives hyperglycemia and liver dysfunction), watch for refeeding (Section 7), and de-escalate to EN as the gut recovers.
Evidence — old → new
2011
EPaNIC. 4640 adults randomized to early PN (within 48 h, to supplement insufficient EN) vs late PN (not before day 8). Late initiation produced faster recovery, fewer new infections (22.8% with late vs 26.2% with early PN; p=0.008), and shorter ICU stays, with no mortality difference. Established that early PN harms — the calorie deficit of the first week is better tolerated than the PN given to fill it.
2014
CALORIES. When PN is used, it is not inherently more dangerous than EN at matched calories (30-day mortality 33.1% vs 34.2%) — the harm in EPaNIC came from early, supplemental overfeeding, not the parenteral route itself. PN is a tool for genuine enteral failure, used at the right time and dose.

What changed. PN shifted from a target-chasing supplement begun on day 1 to a rescue therapy withheld through the first week. The lesson of EPaNIC — that the acute-phase calorie deficit is protective rather than dangerous — reframed all of early ICU nutrition.

In practice

Don’t start PN in the first days to hit a calorie goal. If the gut still cannot deliver adequate nutrition by day 4–7, add supplemental PN guided by nutritional risk, dose it to avoid overfeeding, and switch back to EN as soon as the gut works.

Sources (2)
  • Casaer MP, Mesotten D, Hermans G, et al. Early versus late parenteral nutrition in critically ill adults (EPaNIC). N Engl J Med. 2011;365(6):506–517. DOI 10.1056/NEJMoa1102662. PMID 21714640.
  • Harvey SE, Parrott F, Harrison DA, et al; CALORIES Trial Investigators. Trial of the route of early nutritional support in critically ill adults (CALORIES). N Engl J Med. 2014;371(18):1673–1684. DOI 10.1056/NEJMoa1409860. PMID 25271389.

6Glycemic control

Current approach (2026)
Tight control: higher mortalityTarget 140–180 mg/dL
Treat hyperglycemia, but not too aggressively. The landmark NICE-SUGAR trial showed that targeting a near-normal glucose of 81–108 mg/dL increased mortality versus a target below 180, driven by severe hypoglycemia. Aim for a glucose of 140–180 mg/dL (7.8–10 mmol/L) with IV insulin, avoid hypoglycemia, and pair glucose management with nutrition delivery — overfeeding (especially early PN) is a major driver of the hyperglycemia that then needs insulin. There is no benefit to chasing tight glucose targets in the critically ill.
Evidence
2009
NICE-SUGAR. 6104 ICU patients randomized to intensive (81–108 mg/dL) vs conventional (<180 mg/dL) glucose control. Intensive control increased 90-day mortality (27.5% vs 24.9%; absolute +2.6%) and caused far more severe hypoglycemia (6.8% vs 0.5%). Ended the era of tight glycemic control in the ICU.

What changed. After early single-center enthusiasm for normoglycemia, NICE-SUGAR established that the harm of hypoglycemia outweighs any benefit of tight control — moving the standard to a moderate 140–180 mg/dL target.

In practice

Start insulin for glucose above ~180 mg/dL and target 140–180; protocolize to minimize swings and prevent hypoglycemia. If insulin requirements climb, check for overfeeding — easing the calorie/dextrose load is often the fix.

Sources (1)
  • NICE-SUGAR Study Investigators; Finfer S, Chittock DR, Su SY, et al. Intensive versus conventional glucose control in critically ill patients. N Engl J Med. 2009;360(13):1283–1297. DOI 10.1056/NEJMoa0810625. PMID 19318384.

7Refeeding syndrome

Current approach (2026)
Restrict calories if it developsReplace phosphate
In patients at risk — chronic undernutrition, alcohol use disorder, prolonged fasting, or little intake before ICU — reintroducing nutrition can precipitate refeeding syndrome: insulin-driven shifts cause hypophosphatemia, hypokalemia, and hypomagnesemia with risk of arrhythmia and cardiac failure. Identify risk early, start feeding low and slow, and monitor and replace electrolytes (especially phosphate) with thiamine supplementation. If refeeding hypophosphatemia develops, the evidence supports restricting calories (not pushing through): a randomized trial found that caloric restriction during refeeding hypophosphatemia improved survival — a secondary outcome; its primary endpoint (days alive after discharge) was neutral — versus continued standard feeding.
Evidence
2015
Doig (refeeding RCT). 339 critically ill adults who developed refeeding hypophosphatemia were randomized to continued standard caloric delivery vs protocolized caloric restriction. Restriction did not change the primary outcome (days alive after discharge) but improved 60-day and longer-term survival and reduced infections — supporting “feed less” when refeeding biochemistry appears.

What changed. Refeeding shifted from a vague caution to an actionable protocol: screen for risk, replace phosphate aggressively, give thiamine, and — crucially — cut calories rather than feeding through a falling phosphate.

In practice

Flag high-risk patients before feeding; start at a low rate with thiamine and check phosphate, potassium, and magnesium. If phosphate drops on refeeding, replace it and dial calories back for a few days rather than continuing to advance.

Sources (1)
  • Doig GS, Simpson F, Heighes PT, et al; Refeeding Syndrome Trial Investigators Group. Restricted versus continued standard caloric intake during the management of refeeding syndrome in critically ill adults: a randomised, parallel-group, multicentre, single-blind controlled trial. Lancet Respir Med. 2015;3(12):943–952. DOI 10.1016/S2213-2600(15)00418-X. PMID 26597128.

8GI intolerance & delivery

Current approach (2026)
Don’t chase gastric residualsProkinetics / post-pyloric for intolerance
Maximize safe delivery without over-reacting to “intolerance.” Routine measurement of gastric residual volume (GRV) should not be used to stop feeding — withholding EN for high residuals worsens delivery without preventing pneumonia, and many units have abandoned GRV monitoring or raised the threshold to ~500 mL. For genuine intolerance (vomiting, distension, large residuals), try prokinetics (metoclopramide or low-dose erythromycin — both prolong the QT interval, so correct potassium and magnesium, monitor QTc, and limit the course to a few days) and consider post-pyloric (small-bowel) feeding, which improves tolerance and may reduce aspiration risk in high-risk patients. Keep the head of bed elevated, and remember that EN can usually continue during prone positioning and modest vasopressor support.

Why it matters. The biggest cause of underfeeding in the ICU is not the prescription but interruptions — for procedures, perceived intolerance, and reflexive GRV checks. Reducing unnecessary stoppages closes the gap between prescribed and delivered nutrition more than any formula change.

In practice

Don’t stop EN for an isolated high residual; treat true intolerance with a prokinetic and, if it persists, place a post-pyloric tube rather than switching to PN. Minimize feeding interruptions, elevate the head of bed, and continue EN in prone or stable low-dose vasopressor patients.

Sources (2)
  • Reignier J, Mercier E, Le Gouge A, et al; Clinical Research in Intensive Care and Sepsis (CRICS) Group. Effect of not monitoring residual gastric volume on risk of ventilator-associated pneumonia in adults receiving mechanical ventilation and early enteral feeding: a randomized controlled trial. JAMA. 2013;309(3):249–256. DOI 10.1001/jama.2012.196377. PMID 23321763.
  • McClave SA, Taylor BE, Martindale RG, et al. Guidelines for the provision and assessment of nutrition support therapy in the adult critically ill patient (SCCM/ASPEN). JPEN J Parenter Enteral Nutr. 2016;40(2):159–211. DOI 10.1177/0148607115621863. PMID 26773077.

9Special populations & micronutrients

Current approach (2026)
No routine glutamineAdjust for AKI/CRRT, obesity
Tailor the plan to the host, and avoid unproven supplements. Do not give high-dose glutamine to critically ill patients with multi-organ failure — the REDOXS trial found it increased mortality. There is no routine role for pharmaconutrient cocktails, high-dose antioxidants, or (on current evidence) high-dose IV vitamin C or routine vitamin D in the unselected ICU patient. Adjust for specific situations: in AKI on CRRT, account for amino-acid and micronutrient losses across the filter while still avoiding excessive protein; in obesity, use adjusted/ideal body weight for targets (high-protein hypocaloric strategies are commonly used but not strongly evidence-based); in hepatic failure, do not protein-restrict for encephalopathy. Correct overt micronutrient and electrolyte deficiencies, and give thiamine where deficiency is plausible.
Evidence
2013
REDOXS. 1223 critically ill adults with multi-organ failure randomized to high-dose glutamine and/or antioxidants vs placebo. Glutamine showed a trend to increased 28-day mortality and significantly higher in-hospital and 6-month mortality; antioxidants gave no benefit. Overturned enthusiasm for glutamine in the sickest patients.

What changed. The “immunonutrition” era — glutamine, antioxidants, fish-oil cocktails — largely collapsed under randomized scrutiny. Modern practice corrects genuine deficiencies and otherwise avoids supraphysiologic supplements, which have repeatedly failed or harmed.

In practice

Skip routine glutamine and antioxidant megadoses. On CRRT, replace filter losses and keep protein moderate; in obesity, dose to adjusted body weight; don’t protein-restrict hepatic encephalopathy. Treat real deficiencies (including thiamine) rather than supplementing prophylactically.

Sources (2)
  • Heyland D, Muscedere J, Wischmeyer PE, et al; Canadian Critical Care Trials Group. A randomized trial of glutamine and antioxidants in critically ill patients (REDOXS). N Engl J Med. 2013;368(16):1489–1497. DOI 10.1056/NEJMoa1212722. PMID 23594003.
  • Singer P, Blaser AR, Berger MM, et al. ESPEN practical and partially revised guideline: clinical nutrition in the intensive care unit. Clin Nutr. 2023;42(9):1671–1689. DOI 10.1016/j.clnu.2023.07.011. PMID 37517372.

10Monitoring & the recovery transition

Current approach (2026)
Phase-based feedingEscalate in recovery
Think in phases. In the acute phase (roughly days 1–4, often with endogenous energy production and metabolic instability), feed conservatively and avoid overfeeding. As the patient stabilizes into the recovery/anabolic phase, escalate energy and protein toward full targets to rebuild lost muscle — this is when adequate nutrition likely matters most, though it has been harder to study. Monitor for overfeeding (rising glucose and triglycerides, hepatic dysfunction, high CO₂), track delivered vs prescribed nutrition, and re-measure needs (indirect calorimetry) as metabolism changes. At ICU discharge, hand off a clear ongoing plan — many survivors remain underfed on the ward and through rehabilitation.

Why it matters. The same caloric load that is unnecessary (or harmful) on day 2 becomes appropriate in recovery. Most ICU nutrition trials targeted the acute phase; the open question — and the practical opportunity — is feeding the recovering, rehabilitating patient well.

In practice

Match feeding to the phase: gentle early, fuller as the patient turns the corner. Watch for overfeeding signals, measure delivered nutrition (not just prescribed), and ensure the post-ICU plan continues adequate intake into rehabilitation.

Sources (1)
  • Singer P, Blaser AR, Berger MM, et al. ESPEN practical and partially revised guideline: clinical nutrition in the intensive care unit. Clin Nutr. 2023;42(9):1671–1689. DOI 10.1016/j.clnu.2023.07.011. PMID 37517372.

11Where it’s heading (2026)

Personalized energy by measurement. Indirect calorimetry — now easier with newer devices — is moving from research tool toward bedside standard, replacing imprecise predictive equations so feeding can be matched to measured metabolism phase by phase.

The recovery phase & muscle. Because the acute-phase trials were uniformly “more is not better,” attention is shifting to the post-acute and rehabilitation period, combining protein with early mobilization and resistance exercise to counter ICU-acquired weakness — the next major trials target function and muscle, not short-term mortality.

Better targeting, not more nutrients. Metabolomic and biomarker approaches aim to identify the minority who might benefit from specific strategies, after a decade in which one-size-fits-all aggressive feeding and pharmaconutrients repeatedly failed.

Continuity beyond the ICU. Recognizing that many survivors stay underfed on the ward and at home, post-ICU nutrition follow-up and oral nutrition support are increasingly built into recovery pathways.

12Bottom line — the nutrition workflow

  1. Use the gut, early. Start enteral nutrition within 24–48 h once resuscitated; prefer EN over PN (the route doesn’t change survival — CALORIES).
  2. Start modest, don’t chase calories. In the acute phase, full/energy-dense feeding gives no benefit (EDEN, TARGET, PermiT) — advance toward goal over the first week.
  3. Protein ~1.2–1.3 g/kg/day. Higher protein offers no benefit and may harm the sickest and those with AKI (EFFORT, PRECISe).
  4. Don’t start PN early. Withhold supplemental PN until ~day 4–7 when EN is insufficient — early PN harms (EPaNIC).
  5. Feed shock gently. Early low-dose EN; full EN causes bowel complications (NUTRIREA-2), and low calorie/protein speeds recovery (NUTRIREA-3).
  6. Glucose 140–180 mg/dL. Avoid tight control — it raises mortality via hypoglycemia (NICE-SUGAR).
  7. Guard against refeeding. Screen high-risk patients, give thiamine, replace phosphate, and restrict calories if refeeding hypophosphatemia appears (Doig 2015).
  8. Don’t over-react to residuals. Stop chasing GRV; treat true intolerance with prokinetics or post-pyloric feeding; minimize interruptions.
  9. Skip glutamine & megadose supplements. Glutamine harms in organ failure (REDOXS); correct real deficiencies instead.
  10. Escalate in recovery. Feed fuller as the patient turns anabolic, measure delivered nutrition, and continue the plan beyond the ICU.

13FAQ

When should enteral nutrition be started in the ICU?
Within 24 to 48 hours of admission once the patient is resuscitated, using the enteral route in preference to parenteral nutrition (ASPEN/SCCM, ESPEN). Start at a modest rate rather than racing to the calorie goal. In shock, enteral nutrition is not contraindicated but should be low-volume and cautious, because full early enteral feeding caused more bowel complications in NUTRIREA-2.
How many calories should a critically ill patient receive?
In the acute phase, do not aim for full calculated needs. Trials of full feeding (EDEN), energy-dense formula (TARGET), and permissive underfeeding (PermiT) all showed that fewer calories early is safe and that more calories do not improve survival. A practical approach is roughly 70% of estimated needs building toward goal over the first week, with protein maintained, and using indirect calorimetry to set needs when available.
Is high-protein feeding better for critically ill patients?
No. A moderate target of about 1.2 to 1.3 g/kg/day is appropriate. The EFFORT Protein trial found that high protein (2.2 g/kg/day or more) did not improve survival or time to discharge and signaled harm in the sickest patients and those with acute kidney injury, and PRECISe found no functional-recovery benefit. Keep protein moderate, especially in AKI before dialysis.
When should parenteral nutrition be started?
Only when enteral nutrition is impossible or persistently insufficient, and not early. The EPaNIC trial showed that starting parenteral nutrition on day 1 to 2 caused more infections and slower recovery than waiting until day 8. Most guidelines suggest waiting until about day 4 to 7 before adding supplemental parenteral nutrition to close a persistent caloric gap, dosed to avoid overfeeding.
What glucose target is recommended in the ICU?
A moderate target of 140 to 180 mg/dL (7.8 to 10 mmol/L). The NICE-SUGAR trial showed that tight control (81 to 108 mg/dL) increased mortality, largely through severe hypoglycemia. Start insulin above roughly 180 mg/dL, avoid hypoglycemia, and reduce the calorie or dextrose load if insulin requirements climb, since overfeeding drives much ICU hyperglycemia.
Should glutamine or immunonutrition be used?
No, not routinely. The REDOXS trial found that high-dose glutamine increased mortality in critically ill patients with multi-organ failure, and high-dose antioxidants gave no benefit. There is no routine role for glutamine, antioxidant megadoses, or other pharmaconutrient cocktails; correct genuine micronutrient deficiencies and give thiamine where deficiency is plausible instead.

15Guidelines & evidence basis

Badges summarize each recommendation’s basis: Guideline: strong Guideline: conditional RCT benefit RCT neutral RCT harm. Guideline strengths use the GRADE classes quoted from the documents below.

Guidelines referenced (2)
  • McClave SA, Taylor BE, Martindale RG, et al. Guidelines for the provision and assessment of nutrition support therapy in the adult critically ill patient: Society of Critical Care Medicine (SCCM) and American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.). JPEN J Parenter Enteral Nutr. 2016;40(2):159–211. DOI 10.1177/0148607115621863. PMID 26773077. — enteral over parenteral, early EN, and assessment of nutrition risk.
  • Singer P, Blaser AR, Berger MM, et al. ESPEN practical and partially revised guideline: clinical nutrition in the intensive care unit. Clin Nutr. 2023;42(9):1671–1689. DOI 10.1016/j.clnu.2023.07.011. PMID 37517372. — phase-based energy/protein targets, indirect calorimetry, and avoidance of early overfeeding.

Disclaimer. This page is an educational summary of published evidence for clinicians and is not a substitute for individual clinical judgment or institutional protocols. Targets, doses, and thresholds are taken from the cited trials and guidelines; verify against current product labeling, local protocols, and patient-specific factors before applying. “In practice” notes are general practical guidance. Recommendation strengths are quoted from the cited guidelines (GRADE). Reviewed by the DosePilot Medical Team (Jun 2026); all citations verified against PubMed (PMID) and DOI.