Explanation
Nutrition is essential for all organisms. In this module, we cover the fundamentals of nutrition therapy and discuss energy, proteins, fats, carbohydrates, vitamins, and minerals. We will also talk about water and hydration.
When patients with dysphagia eat orally, we need to be mindful of the texture (form) of the food that they eat. Some textures of food make it difficult for them get the nutrition they need. So, in some cases, we need to supplement eating orally with other types of eating.
Energy requirements are best calculated with actual measurement, but when this is difficult, we can use an equation to estimate basal metabolic rate instead.
Nutrient requirements are based on the applicability and age-appropriate requirements stated in the Dietary Reference Intakes for Japanese1. However, the Dietary Reference Intakes for Japanese may not be applicable in people with certain underlying diseases.
Explanation
In the late 1990s, a Ministry of Health, Labour and Welfare study group conducted a survey to determine the number of people in Japan with undernutrition2. At this time, assessments of undernutrition were based on levels of serum albumin, a protein in blood with a half-life of approximately 20 days. Low serum albumin levels are thought to signify persistent reduced appetite and poor nutritional status for at least 2 weeks prior to measurement. The survey found that serum albumin levels < 3.5 g/dL were detected in < 1% of patients during comprehensive medical examinations but were found in roughly 40% of hospitalized patients. A 2015 survey reported undernutrition in roughly 40% of patients in acute care hospitals and roughly 50% of patients in rehabilitation hospitals. Prevention of, and recovery from, undernutrition both require appropriate nutritional intake.
Explanation
Because elderly people are prone to undernutrition, simple nutritional status screenings are commonly performed. One instrument used for nutritional screening is the Mini Nutritional Assessment Short Form (MNA-SF). The MNA-SF is used to assess nutritional status in people aged ≥ 65 years in a simple manner. The latest version, a 6-item version completed at the 2009 World Congress of the International Association of Gerontology and Geriatrics (IAGG), is currently used in Japan and many other countries around the world.
The 6 items of the MNA-SF are as follows: A) Has food intake declined over the past 3 months due to loss of appetite, digestive problems, chewing or swallowing difficulties? B) Weight loss during the last 3 months; C) Mobility; D) Has suffered psychological stress or acute disease in the past 3 months? E) Neuropsychological problems; F) BMI (kg/m2) as determined by weight (kg) ÷ height (m)2 or calf circumference (when BMI is not available).
As already mentioned, undernutrition can be measured easily. When there is a high likelihood of undernutrition, we need to make a definitive assessment based on physical measurements and blood testing.
Explanation
Here are the results of roughly 3 years of observation of hospitalized patients who were classified based on MNA results as having normal nutritional status, being at risk of malnutrition, and being malnourished. At 1000 days of hospitalization, roughly 80% of inpatients with normal nutritional status had survived versus roughly 20% of malnourished patients. As these results show, nutrition management is a major factor in survival outcomes.
Explanation
When deciding an appropriate level of nutrients to administer, we must first decide energy intake. We can do this either 1) through actual measurement with indirect calorimetry or 2) using an equation to estimate basal metabolic rate. Most hospitals and medical facilities use the latter. There are multiple equations for estimating basal metabolic rate, some of which were designed specifically for the Japanese population (see the next slide for a detailed explanation of these equations).
The values yielded by these calculations of basal metabolic rate are multiplied by an activity factor or a stress factor to determine the energy requirements. Basal metabolic rate is measured during early morning fasting in a comfortable indoor environment with patients in a resting supine position, so this is why we add the activity level or stress level to this base value.
Explanation
Let's look at 3 equations for estimating basal metabolic rate. Equations 1) and 2) were designed specifically for Japanese people1,3, while Equation 3) was designed for Americans4. In Equation 1), weight (kg) is entered as a variable. In Equation 2), in addition to height (cm), weight (kg), and age, sex is taken into consideration as a constant; 0.4235 is entered as a constant for men and 0.9708 is entered for women. In Equation 3), height (cm), weight (kg), and age are entered. According to a recent study, Equations 1) and 2) yield less error than Equation 3) when used to determine basal metabolism in Japanese people5.
Explanation
Once we have determined energy requirements, we next need to determine the protein requirements, which is based on the results of several nitrogen balance experiments reported from 1973 to 1983. In a nitrogen balance experiment conducted with 154 subjects using high-quality protein from chicken eggs, the minimum nitrogen intake needed to maintain nitrogen balance was calculated as 0.65 g/kg body weight/day1.
In the Dietary Reference Intakes for Japanese (2015 edition), the recommended dietary allowance of protein was calculated by dividing this 0.65 by 0.9 (as the digestion/absorption rate of mixed dietary protein was assumed to be 90%) and then multiplied by 1.25 (the rate of variability in individual differences). Based on this formula, the recommended allowance of protein is 0.9 g/kg/day.
However, the amount of protein required by an organism fluctuates based on the following factors.
- When energy intake increases, the protein sparing effect shifts nitrogen balance in a positive direction. A positive-leaning nitrogen balance shows that protein is being accumulated in the body. On the flip side, when energy intake decreases, protein must be burned as energy, causing the required intake of protein to increase.
- Infection, trauma, and stress put protein metabolism in a catabolic state, thereby increasing the required intake of protein.
It is reported that large numbers of patients in care facilities and elderly patients convalescing at home have a negative nitrogen balance, that is, the amount of protein used by their bodies exceeds their level of protein intake6.
Explanation
Next, let's consider intake of fats. The point here is to prevent insufficiency of essential fatty acids that can't be synthesized in the body. Essential fatty acids consist of n-6 polyunsaturated fatty acids and n-3 polyunsaturated fatty acids.
A deficiency of n-6 polyunsaturated fatty acids causes rough skin to develop into dermatitis7. A deficiency of n-3 polyunsaturated fatty acids results in dermatitis and delayed wound healing8 Preventing n-6 polyunsaturated fatty acid deficiency requires 2% of energy from linoleic acid. Preventing n-3 polyunsaturated fatty acid deficiency requires 0.5−1.0% of energy from α-linolenic acid. Based on these issues, in a normal diet, it is unlikely to have insufficiency of essential fatty acids if 20% of the energy intake comes from fats.
Explanation
For nutrients other than those discussed so far, the goal is to obtain the recommended dietary allowance or the adequate intake defined by Dietary Reference Intakes for Japanese. Recommended dietary allowances are calculated based on scientific evidence to avoid insufficiency in studies involving human subjects, while adequate intakes are set based on the results of animal experiments (this is because experiments related to adequate intake have not been performed with human subjects due to the difficulties inherent in such experiments). The Dietary Reference Intakes for Japanese prescribes recommended dietary allowances and adequate intakes by age and sex for nutrients for which people may not meet the required amounts.
However, for some underlying diseases, certain nutrients are limited to prevent the disease from progressing.
Patients with dysphagia are susceptible to dehydration. To avoid this, patients must obtain sufficient hydration: adults require approximately 40-50 mL of water per kilogram of body weight, while elderly people require roughly 30-40 mL of water per kilogram of body weight. Dietary water volume is subtracted from the above values to calculate the required amount of liquid water. As a rough calculation, most adults require > 1000 mL of water. However, if hydration must be restricted due to a condition such as heart disease or edema, the restriction must be followed. Patients who drink thickened liquids (water, tea, etc) have an increased risk of dehydration due to reduced water intake.
Explanation
Suitable food texture must be determined to ensure that intake of energy, protein, and other necessary nutrients is maintained orally.
However, adjusting food texture increases the volume of water in the food, thus reducing the amount of nutrients per unit weight. This situation can easily lead to a deficiency in required nutrients, where we need to consider other methods of eating.
One possible alternative is feeding via the intestines (enteral nutrition). A nasogastric tube is the first access route considered to the stomach or intestines. If enteral nutrition is to be continued long-term, gastrostomy is also considered.
Explanation
When nutritional requirements can't be met through eating orally, the first alternative to consider is enteral nutrition. There are more than 100 total types of dietary and medical nutrition products used in enteral nutrition. The medical products are called enteral nutrition formulas, while dietary products are called concentrated liquid diets. The main nutrition products used for patients with dysphagia are normal liquid diets derived from natural foods, blended food, and natural concentrated liquid diets. Normal liquid diets include foods such as thin rice gruel, vegetable soup, and fruit juice. Blended food includes congee and other foods that have been mixed in a blender. However, blended foods can easily clog feeding tubes. Natural concentrated liquid diets include liquid diets made from natural foods. Non-natural foods primarily consist of materials chosen for their digestibility.
Explanation
When we are considering long-term use of enteral nutrition formulas or concentrated liquid diets, we should consider providing the enteral nutrition formulas via gastrostomy. A gastrostomy tubes are thicker than nasogastric tubes, so it is less prone to clogging, which then allows the use of highly viscous foods and semi-solid foods that can't be used with a nasogastric tube.
Administration of nutrients through a gastrostomy tube may involve problems such as diarrhea, gastroesophageal reflux, and leakage of nutrition formulas. If any of these symptoms occur, consider using semi-solid enteral nutrition formulas.
Although some semi-solid nutrition formulas are commercially available, individual medical facilities can mix the enteral nutrition formulas and enriched liquid diets they already use with commercially available thickening agents. Some commercially available thickeners are specifically for thickening enteral nutrition formulas. Another method is to solidify enteral nutrition formulas and concentrated liquid diets with agar.
Explanation
When there are obstacles to using enteral nutrition formulas, we can administer nutrients intravenously. There are two options for this through a peripheral vein (peripheral parenteral nutrition) or a central vein (total parenteral nutrition).
Peripheral parenteral nutrition, the supply of nutrition through a peripheral vein in an extremity, can be used to administer up to 1000 kcaL/day for up to 2 weeks.
Total parenteral nutrition, which generally involves the supply of nutrition through the subclavian vein, can be used to administer as many nutrients as necessary. However, catheter-associated infection can occur.
When the intestines are bypassed, we need to exercise caution because there is a decrease in the number of cells in the intestinal mucosa responsible for immunity. In addition, intestinal bacteria penetrate the intestinal wall, causing adverse effects (bacterial translocation).
Explanation
When patients with dysphagia drink water, we must thicken the water. Some patients may cough on water or tea but can drink milk or other slightly thick liquids. We must be careful not to thicken liquids too much, however. Due to the interaction between thickening agents and liquids, the same amount of thickening agent may not necessarily result in the same thickening with different liquids. The degree of thickening is also affected by temperature. Generally, cold foods and drinks are thick, while warm foods and drinks are thin. When drinks can't be thickened, we should consider hydration with jelly. If patients have difficulty drinking water despite the use of thickening agents or jelly, we need to switch to hydration via a tube.
References
- Plan of Ministry of Health, Labor and Welfare. Dietary References Intake for Japanese(2015)Daiichi shuppan
- Ganpule AA, Tanaka S, Ishikawa-Takata K, Tabata I: Interindividual variability in sleeping metabolic rate in Japanese subjects. Eur J Clin Nutr. 2007 61(11):1256-61
- Harris JA, Benedict FG A Biometric study of basal metabolism in man. Carnegie Institution of Washington, 1919
- Miyake R, Tanaka S, Ohkawara K, Ishikawa-Tanaka K, Hikihara Y, Taguri E, Kayashita J, Tabata I: Validity of Predictive Equations for Basal Metabolic Rate in Japanese Adults. J Nutr Sci Vitaminol, 57, 224-232, 2011
- Hidemichi Ebisawa et al: Study of Essential Amino Acids.136,9-12 1992
- Jeppesen PB et al: Am J Clin Nutr. 68, 126-133, 1998
- Bjerve KS: J Intern Med Suppl. 225, 171-175, 1989
