Nutrition requirements
Outline the daily nutritional requirements, including electrolytes, for a normal 70 kg adult
Macronutrient energy content
| Macronutrient | Caloric content |
|---|---|
| Lipids | 9 kcal/g |
| Protein | 4 kcal/g |
| Carbohydrates | 4 kcal/g |
Empirical nutritional requirements
The following is an empirical 'general' nutritional requirement which can be tailored further for the individual patient.
| Macronutrients | |
| Energy | 25 kcal/kg/day (based on ideal body weight) |
| Water | 30 mL/kg/day + additional losses |
| Carbohydrates | 4 g/kg/day Sources: starches, bread, plants |
| Protein | 1.5g/kg/day Diet must include the 9 essential amino acids which cannot be made endogenously:
Sources: meat, mushrooms, some vegetables |
| Lipids | 1g/kg/day Diet must include the 2 essential fatty acids which cannot be made endogenously:
Sources: oils, (red) meat, butter |
| Micronutrients | |
| Vitamins | Organic compounds that are essential for metabolic functions but cannot be synthesised endogenously in quantities significant enough for survival. They must be obtained through diet. Fat soluble vitamins: A, D, E, K Water soluble vitamins: B vitamins (B1-3, B5-7, B9, B12), C |
| Trace elements | Inorganic compounds used as cofactors for synthesis of various compounds and as catalysts for many redox reactions. They are required in minute quantities and many may be toxic if ingested in excess. Examples: iron, selenium, chromium, manganese, zinc, copper |
| Electrolytes | Na+: 2mmol/kg/day |
Adjusting requirements for the individual
BMR can be estimated using predictive equations (e.g. Harris–Benedict), often multiplied by a stress factor for different critical illness states.
BMR can be measured more accurately by indirect calorimetry (e.g. metabolic cart).
Situations requiring modification:
- Burns or major trauma: increased (hypercaloric) requirements
- Obesity: hypocaloric feeding with relatively high protein
- Chylothorax: fat-free nutrition with higher protein intake