7 Testing plan 58
7.3 Ideal nutritional intake 61
There are various methods to calculate the ideal nutritional intake for people. Most accurate is indirect calorimetry, which measures temperature changes (called thermogenesis), consumption of oxygen or production of carbon dioxide because of metabolism. This makes it possible to measure the basal metabolic rate (BMR), which is the amount of energy expended in a resting (but awake) state (Powell, Paluch, & Blair, 2011). 60% to 75% of the total energy expenditure (TEE) is from the basal metabolic rate of maintaining major body functions and another 10% for the digestion of food (Poehlman, 1989). The third aspect of TEE is the physical activity-‐induced energy expenditure (PAEE), which accounts for 15-‐30% of the TEE, but is the most variable component of TEE (Choquette, Chuin, Lalancette, Brochu, & Dionne, 2009). Other factors of TEE, but less common on average people, are growth (35% of TEE in first three months after
birth, 5% at 12 months, 3% at age 2 and negligible in late teen years), pregnancy and lactation (Food and Agriculture Organization of the United Nations, 2004). The basal metabolic rate is influenced by “factors as age, sex, body size and composition, body temperature, thermogenic hormones, and prior exercise”. It provides energy for all the organs of the body in rest (Poehlman, 1989). The basal metabolic rate can be estimated using a formula, which was developed in 1919 by J. Arthur Harris and Francis G. Benedict and is therefore called the Harris-‐Benedict equation. Using an indirect calorimeter the basal metabolic rate (BMR, in kilocalories per 24 hours) was measured, which led to the equation: BMR men (kcal / day): 66,4730 + 13,7516 * weight + 5,0033 * height – 6,7550 * age BMR women (kcal/day): 655,0955 + 9,5634 * weight + 1,8496 * height – 4,6756 * age Weight is in kilograms, height is in centimetres and age in years. To calculate the recommended daily calorie intake, the BMR is multiplied with a variable value for no exercise (1,2) to very heavy exercise (1,9). Some new studies have
compared the Harris-‐Benedict formula with measured metabolic rate, and often found a 5% difference (Frankenfield, Muth, & Rowe, 1998). However, a study applying Harris-‐Benedict equation to malnourished patients “seriously question[ed] the reliability of the Harris Benedict equations in malnourished patients”. The Harris-‐Benedict equation used a normal and healthy population to derive the formula, but hospital patients especially with undernourishment apparently fall outside the scope of the formula (Moza & Shizgal, 1984).
In this research recommendations from the Danish government for hospital food will be used, since the hospital where the experiment will take place uses these guidelines of Ministeriet for Fødevarer, Landbrug og Fiskeri (2009). The
calculations for the ideal energy and protein intake are similar to those of the Harris-‐Benedict equation, but instead of applying a linear formula, different categories have been used (weight, patients mostly laying in bed or being able to walk, fever, whether patient needs to increase weight). Advised energy and protein intake for 24 hours is showed in table 7.1. Energy values are in kilo joules (kJ); 1 kcal is about 4,18 kJ. When the patient has a fever the amounts need to be multiplied with a certain factor; for 38˚ this is 1,2, for 39˚ this is 1,3 and for 40˚ this is a factor of 1,4. When the BMI is higher than 30, there is a completely other calculation for energy and protein needs. For patients laying in bed the energy is weight * 85kJ and for protein weight * 0,9 grams; for patients being able to walk the energy is weight * 100kJ and for proteins weight * 1,1 grams.
Table 7.1: Energy needs in kJ and the protein needs (between parentheses) in grams for hospitalized patients, per 24 hours. Source: Ministeriet for Fødevarer, Landbrug og Fiskeri (2009).
Keep weight Increase weight
Weight Laying in bed Walking Laying in bed Walking
90kg 9 000 (95) 10 000 (105) 11 000 (115) 13 000 (135) 85kg 80kg 8 000 (85) 9 000 (95) 10 000 (105) 75kg 11 000 (115) 70kg 7 000 (75) 8 000 (85) 9 000 (95) 65kg 10 000 (105) 60kg 8 000 (85) 55kg 6 000 (65) 7 000 (75) 9 000 (95) 50kg 45kg 6 000 (65) 7 000 (75) 8 000 (85) 40kg 5 000 (55)
Interesting to know is that 1kg weight loss corresponds to 20 megajoules (MJ). When the patient is daily eating 2MJ too little, for a week that will sum up to a loss of 0,7kg. But for 1kg gaining weight, you need 30MJ. Recovery to the original healthy weight is therefore difficult (Ministeriet for Fødevarer, Landbrug og Fiskeri, 2009).
In the Aalborg hospital, the dietitians’ goal is to keep the weight of the patient constant. It is not considered realistic to increase the weight of patients to a level of a normal healthy person. After the patient is discharged from the hospital, he or she will probably gain weight again. The two most right columns of table 7.1 are therefore generally not used in the Aalborg hospital. For patients with obesity it is not the intention to let them loose weight, as the muscle strength is the first that is lost, and the immune system will be weakened, which will not help with recovery.
The Danish government has also set up recommendations for the consistency of hospital food. The energy division for hospital food is on average 18% protein, 40% fat and 42% carbohydrates for patients at nutritional risk. Compared to normal food that has 15% protein, 30% fat and 55% carbohydrates, the hospital food for patients at nutritional risk has more fat and proteins. The advised division of energy throughout the day for hospital food is as follows: 20-‐25% in the morning, 20-‐25% in the afternoon, 25-‐30% in the evening and 15-‐30% as in between snacks. Patients with a small appetite eat less in the morning, afternoon and evening, but should have higher energy intake from in between snacks (30-‐ 50%) (Ministeriet for Fødevarer, Landbrug og Fiskeri, 2009). However,
energy and protein intake (Holst, Mortensen, Jacobsen, & Rasmussen, 2010). Dietitians at the Aalborg hospital advise patients at nutritional risk to take a daily vitamin and mineral tablet, because patients are advised to consume higher levels of protein and fat, there is less room in the menu left for fruits and
vegetables.
Besides food intake, drinking enough fluids is also important. A person with not much physical activity needs around 2500mL a day. 300mL is obtained from metabolic reactions, 1000mL from food and 1200mL has to be from beverages. But illness can increase the needs enormously. Fever can cause the patient to transpire more, which increases the needs by 20%. Patients with burn wounds can lose 4-‐8 litres a day, diabetes mellitus and especially diabetes insipidus patients may need an additional 10 litres, and diarrhoea, vomiting and internal infections can require 5-‐10 litres a day (Ministeriet for Fødevarer, Landbrug og Fiskeri, 2009). The amount of liquid intake can vary for certain kinds of patients and is therefore more difficult to determine than for food. In Aalborg hospital different criteria (or a combination of it) is used: 35mL per kilogram bodyweight (40mL for patients with fever), the colour of the urine (dark urine is a sign of dehydration), recommendations for patients with certain diseases (e.g. kidney patients in dialysis) or electrolyte concentrations in blood samples.