What are the different types of enteral (enteral nutrition) diets?

Types of Enteral Nutrition Diets

Start with standard polymeric formulas for all patients requiring enteral nutrition unless specific contraindications exist—this is the first-line choice recommended by the American Society for Parenteral and Enteral Nutrition due to nutritional completeness and cost-effectiveness. 1

Primary Classification System

Enteral nutrition formulas are organized into four main categories based on composition and clinical indication:

1. Standard Polymeric Formulas (First-Line Choice)

• These formulas are appropriate for the vast majority of patients with a functioning gastrointestinal tract and should be your default selection. 1
• They contain intact whole proteins, carbohydrates from partially hydrolyzed starch, and lipids predominantly as long-chain triglycerides (LCTs), providing complete nutrition for most patients 1
• Available in standard energy density (1.0 kcal/ml) and high-energy versions (1.5 kcal/ml), with most formulations containing fiber and being lactose-free and gluten-free 1, 2
• These formulas are nutritionally complete and can serve as the sole source of nutrition for prolonged periods, containing balanced macro- and micronutrients including essential amino acids, essential fatty acids, vitamins, and minerals 1
• Standard formulas generally meet energy, protein, and micronutrient needs with 1.5 L of formula 2

2. Predigested/Elemental Formulas (Limited Indications)

• Reserve these formulas exclusively for patients with documented malabsorption or maldigestion—the European Society for Clinical Nutrition and Metabolism explicitly recommends standard polymeric over elemental formulas for most conditions, including active inflammatory bowel disease. 1
• These formulas contain nitrogen as short peptides or free amino acids, with medium-chain triglycerides (MCTs) to facilitate absorption 1, 2
• Peptide-based formulas facilitate absorption in cases of malabsorption 2
• Free amino acid formulas require supplementation with energy substrates, vitamins, and trace elements 2
• Do not assume elemental formulas are superior due to their higher cost—there is lack of proven benefit in most conditions. 1

3. Disease-Specific Formulas (Use Only With Specific Indications)

• These formulas are modified to address particular metabolic derangements but lack strong evidence for superiority in most conditions—use only when specific indications exist. 1

Renal formulas:

• Reduced protein content and low electrolyte concentrations for patients with chronic kidney disease 1, 2
• Higher protein component, reduced electrolyte content, and high energy density for patients on hemodialysis 2

Hepatic formulas:

• Low sodium and concentrated volume for patients with ascites 1

Other disease-specific formulations:

• Available for various conditions but evidence supporting their use over standard formulas remains limited 1, 3, 4

4. Nutritionally Incomplete Formulas

• Cannot be used as sole nutrition source and require supplementation with additional nutrients 1
• These are typically oral dietary supplements rather than complete enteral nutrition solutions 5

Clinical Selection Algorithm

Follow this stepwise approach:

1. Start with standard polymeric formula (1.0 kcal/ml) for all patients 1
2. Switch to high-energy formula (1.5 kcal/ml) if volume restriction is needed 1
3. Consider predigested formulas only if:
   • Pancreatic insufficiency is documented 1
   • Severe malabsorption is confirmed 1
   • Standard formula fails after adequate trial 1
4. Use disease-specific formulas only for:
   • Chronic kidney disease or hemodialysis (renal formulas) 1, 2
   • Hepatic failure with ascites (hepatic formulas) 1
   • Other specific organ failures with clear metabolic derangements 1

Critical Pitfalls to Avoid

• Never use locally prepared blenderized feeds due to high infection risk and poor micronutrient quality 1
• Do not routinely select elemental formulas based on cost or perceived superiority—they lack proven benefit in most conditions 1
• Avoid switching formulas without adequate trial period of standard polymeric formula first 1
• The choice should be based on specific patient needs and clinical condition, but tolerance depends on composition and individual patient response 2