Nutrition
On this page 6 sections
Caloric Values of Macronutrients
| Nutrient | Approximate energy yield |
|---|---|
| Carbohydrates | 4 kcal/g |
| Protein | 4 kcal/g |
| Fat | 9 kcal/g |
| Alcohol | 7 kcal/g |
Fat is the most energy-dense macronutrient.
General macronutrient distribution
Typical adult dietary patterns often derive approximately 45–65% of energy from carbohydrates, 20–35% from fats and 10–35% from protein. Individual needs vary with health, activity, age and clinical circumstances.
Essential fatty acids
Humans cannot synthesize certain fatty acids in sufficient amounts, so they must be obtained from food.
| Essential fatty acid | Family | Main importance |
|---|---|---|
| Linoleic acid | Omega-6 | Precursor of arachidonic acid |
| Alpha-linolenic acid | Omega-3 | Precursor of longer-chain omega-3 fatty acids |
Deficiency can impair skin integrity, growth and normal cellular function.
Total Parenteral Nutrition
TPN provides nutrients intravenously when gastrointestinal feeding is not feasible or cannot adequately meet nutritional requirements.
Main components
- Dextrose for carbohydrate energy.
- Amino acids for protein requirements.
- Lipid emulsions for energy and essential fatty acids.
- Electrolytes, vitamins and trace elements.
- Water and other components according to individual needs.
Important complications
| Complication | Key issue |
|---|---|
| Hyperglycemia | Excess glucose delivery or impaired glucose control |
| Electrolyte disturbances | Changes in potassium, magnesium and phosphate |
| Refeeding syndrome | Rapid electrolyte shifts, especially hypophosphatemia, after restarting nutrition in severely malnourished patients |
| Essential fatty acid deficiency | Inadequate provision of essential fats |
| Catheter-related infection | Central venous access complications |
| Hepatobiliary complications | Cholestasis and liver dysfunction in some patients |
Clinical tip: Refeeding syndrome can be dangerous. High-risk patients require careful nutritional initiation and monitoring of phosphate, potassium, magnesium, fluid balance and thiamine status.