Nutrition basics
Good nutrition supports healing, immunity, and recovery. Nurses screen for malnutrition and help patients eat well. For study only, not clinical guidance: always follow your programme, current local protocols, and supervising clinicians.
Macronutrients
Carbohydrates are the main energy source, providing about 4 kcal per gram; complex carbohydrates and fibre are preferred. Proteins, about 4 kcal per gram, build and repair tissues and are crucial for wound healing. Fats, about 9 kcal per gram, store energy and carry fat-soluble vitamins; unsaturated fats are healthier than saturated and trans fats.
Micronutrients
Vitamins and minerals are needed in small amounts. Vitamin C and zinc support wound healing; vitamin D and calcium support bones; iron prevents anaemia; vitamin B12 and folate support red blood cells and nerves. Fat-soluble vitamins (A, D, E, K) can accumulate to toxic levels; water-soluble vitamins (B and C) need regular intake.
Water
Water is essential for temperature regulation, circulation, and removing wastes. Needs vary with size, activity, climate, and illness; fever, vomiting, diarrhoea, and burns increase losses. Older adults are at particular risk of dehydration because thirst sensation declines with age.
Dietary guidelines
National guidelines, such as the Dietary Guidelines for Americans and MyPlate, recommend a variety of vegetables, fruits, whole grains, lean proteins, and dairy or alternatives, while limiting added sugars, saturated fat, and sodium. A commonly cited limit is under 2,300 mg of sodium per day for most adults.
Body mass index
Body mass index (BMI) is weight in kilograms divided by height in metres squared: \(\text{BMI} = \frac{\text{kg}}{\text{m}^2}\). For adults, under 18.5 is underweight, 18.5-24.9 healthy weight, 25-29.9 overweight, and 30 or above obesity. BMI is a screening tool; it does not distinguish muscle from fat or account for body composition differences.
Nutrition screening
Hospitals screen patients for malnutrition risk on admission, using tools such as the Malnutrition Universal Screening Tool (MUST), which considers BMI, unplanned weight loss, and acute illness. Unintentional weight loss of more than 5% in a month or 10% in six months is a warning sign. At-risk patients are referred to a dietitian.
Malnutrition in hospital
Malnutrition is common in hospitalised patients, especially older adults, and slows wound healing, weakens immunity, increases falls and pressure injuries, and prolongs stays. Nurses help by assisting with meals, protecting mealtimes from interruptions, offering snacks and supplements, and recording intake.
Worked example
A patient weighs 54 kg and is 1.70 m tall. BMI = 54 / (1.70 x 1.70) = 54 / 2.89, about 18.7. This is just within the healthy range, but she reports losing 6 kg in the past three months without trying, about 10% of her body weight. The nurse flags malnutrition risk and refers her to a dietitian.
Key takeaways
Carbohydrates and proteins provide about 4 kcal/g and fats 9 kcal/g; protein is vital for healing. Vitamins C and zinc aid wound healing; fat-soluble vitamins can accumulate. Hydration needs rise with illness, and older adults are vulnerable. Guidelines favour varied whole foods and limiting sodium. BMI = kg/m^2; 18.5-24.9 is healthy. Screen for malnutrition and unplanned weight loss; help patients eat.
Flashcard
About 4 kcal per gram
Check your understanding
A patient weighs 81 kg and is 1.80 m tall. What is their BMI?