Introduction
Nurses play a vital role in promoting healthy nutrition. They focus on preventing disease, assisting patients in recovering from illness and surgery, and educating patients on managing chronic conditions through appropriate food choices. Healthy nutrition is crucial in preventing obesity and chronic diseases like diabetes mellitus and cardiovascular disease. By actively promoting healthy eating habits, nurses provide patients with the tools to maintain their health, emphasizing the importance of prevention over treatment.
When patients are recovering from illness or surgery, nurses employ strategies to encourage good nutrition, even when patients have a poor appetite or nausea. For patients with chronic diseases, nurses offer education about prescribed diets, such as low-carbohydrate diets for diabetes or low-fat, low-salt, low-cholesterol diets for cardiovascular disease.
Nurses also advocate for patients at risk of nutritional deficits. They may identify difficulties in swallowing and recommend a swallow study to prevent aspiration. They also address psychosocial risk factors in a patient's home environment that could lead to poor nutrition and make appropriate referrals to improve nutritional status. Additionally, nurses administer alternative forms of nutrition, such as enteral (tube) feedings or parenteral (intravenous) feedings.
Basic Concepts of Nutrition
Before delving into assessments and interventions for promoting good nutrition, it's essential to review the digestive system, essential nutrients, and nutritional guidelines.
Digestive System
The digestive system breaks down food and absorbs nutrients into the bloodstream through the small and large intestines. Because overall health relies on good nutrition, any disorder affecting the digestive system can significantly impact health and increase the risk of chronic conditions.
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Structure and Function
The gastrointestinal system (digestive system) is responsible for digestion, absorption, and immune response. Digestion begins in the mouth with mastication, where food is broken down into smaller chunks. The masticated food forms a bolus that moves to the pharynx and then the esophagus. Peristalsis, coordinated muscle movements in the esophagus, moves the bolus into the stomach, where it mixes with acidic gastric juices and is further broken down into chyme. As chyme moves into the duodenum of the small intestine, it mixes with bile from the gallbladder and pancreatic enzymes from the pancreas for further digestion.
Absorption is another critical function. After chyme enters the small intestine, it comes into contact with villi, tiny fingerlike projections that increase the surface area of the small intestine. This allows nutrients, such as protein, carbohydrates, fat, vitamins, and minerals, to absorb through the intestinal wall and into the bloodstream. Absorption of nutrients is essential for metabolism because nutrients fuel bodily functions and create energy. Peristalsis moves leftover liquid from the small intestine into the large intestine, where additional water and minerals are absorbed. Waste products are condensed into feces and excreted from the body through the anus.
In addition to digestion and absorption, the gastrointestinal system is also involved in immune function. Good bacteria in the stomach create a person’s gut biome. Gut biome contributes to a person’s immune response through antibody production in response to foreign materials, chemicals, bacteria, and other substances. Patients may develop Clostridium difficile (C-diff) after taking antibiotics that kill these beneficial bacteria in the gut.
Essential Nutrients
Nutrients from food and fluids are used by the body for growth, energy, and bodily processes. Essential nutrients are necessary for bodily functions but must come from dietary intake because the body cannot synthesize them. These include vitamins, minerals, some amino acids, and some fatty acids. Essential nutrients are divided into macronutrients and micronutrients.
Macronutrients
Macronutrients make up most of a person’s diet and provide energy and essential nutrient intake. Macronutrients include carbohydrates, proteins, and fats. However, too many macronutrients without physical activity can lead to obesity, cardiovascular disease, diabetes mellitus, kidney disease, and other chronic diseases. Too few macronutrients result in undernutrition, which contributes to nutrient deficiencies and malnourishment.
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Carbohydrates
Carbohydrates are sugars and starches and are an important energy source that provides 4 kcal/g of energy. Simple carbohydrates are small molecules (monosaccharides or disaccharides) and break down quickly. As a result, simple carbohydrates are easily digested and absorbed into the bloodstream, so they raise blood glucose levels quickly. Examples of simple carbohydrates include table sugar, syrup, soda, and fruit juice. Complex carbohydrates are larger molecules (polysaccharides) that break down more slowly, which causes slower release into the bloodstream and a slower increase in blood sugar over a longer period of time. Examples of complex carbohydrates include whole grains, beans, and vegetables.
Foods can also be categorized according to their glycemic index, a measure of how quickly glucose levels increase in the bloodstream after carbohydrates are consumed. The glycemic index was initially introduced as a way for people with diabetes mellitus to control their blood glucose levels. For example, processed foods, white bread, white rice, and white potatoes have a high glycemic index. They quickly raise blood glucose levels after being consumed and also cause the release of insulin, which can result in more hunger and overeating. However, foods such as fruit, green leafy vegetables, raw carrots, kidney beans, chickpeas, lentils, and bran breakfast cereals have a low glycemic index. These foods minimize blood sugar spikes and insulin release after eating, which leads to less hunger and overeating. Eating a diet of low glycemic foods has been linked to a decreased risk of obesity and diabetes mellitus.
Proteins
Proteins are peptides and amino acids that provide 4 kcal/g of energy. Proteins are necessary for tissue repair and function, growth, energy, fluid balance, clotting, and the production of white blood cells. Protein status is also referred to as nitrogen balance. Nitrogen is consumed in dietary intake and excreted in the urine and feces. If the body excretes more nitrogen than it takes in through the diet, this is referred to as a negative nitrogen balance. Negative nitrogen balance is seen in patients with starvation or severe infection. Conversely, if the body takes in more nitrogen through the diet than what is excreted, this is referred to as a positive nitrogen balance. During positive nitrogen balance, excess protein is converted to fat tissue for storage.
Proteins are classified as complete, incomplete, or partially complete. Complete proteins must be ingested in the diet. They have enough amino acids to perform necessary bodily functions, such as growth and tissue maintenance. Examples of foods containing complete proteins are soy, quinoa, eggs, fish, meat, and dairy products. Incomplete proteins do not contain enough amino acids to sustain life. Examples of incomplete proteins include most plants, such as beans, peanut butter, seeds, grains, and grain products. Incomplete proteins must be combined with other types of proteins to add to amino acids and form complete protein combinations. For example, vegetarians must be careful to eat complementary proteins, such as grains and legumes, or nuts and seeds and legumes, to create complete protein combinations during their daily food intake. Partially complete proteins have enough amino acids to sustain life, but not enough for tissue growth and maintenance. Because of the similarities, most sources consider partially complete proteins to be in the same category as incomplete proteins.
Fats
Fats consist of fatty acids and glycerol and are essential for tissue growth, insulation, energy, energy storage, and hormone production. Fats provide 9 kcal/g of energy. While some fat intake is necessary for energy and uptake of fat-soluble vitamins, excess fat intake contributes to heart disease and obesity. Due to its high-energy content, a little fat goes a long way.
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Fats are classified as saturated, unsaturated, and trans fatty acids. Saturated fats come from animal products, such as butter and red meat (e.g., steak). Saturated fats are solid at room temperature. Recommended intake of saturated fats is less than 10% of daily calories because saturated fat raises cholesterol and contributes to heart disease.
Unsaturated fats come from oils and plants, although chicken and fish also contain some unsaturated fats. Unsaturated fats are healthier than saturated fats. Examples of unsaturated fats include olive oil, canola oil, avocados, almonds, and pumpkin seeds. Fats containing omega-3 fatty acids are considered polyunsaturated fats and help lower LDL cholesterol levels. Fish and other seafood are excellent sources of omega-3 fatty acids.
Trans fats are fats that have been altered through a hydrogenation process, so they are not in their natural state. During the hydrogenated process, fat is changed to make it harder at room temperature and have a longer shelf life. Trans fats are found in processed foods, such as chips, crackers, and cookies, as well as in some margarines and salad dressings. Minimal trans fat intake is recommended because it increases cholesterol and contributes to heart disease.
Micronutrients
Micronutrients include vitamins and minerals.
Vitamins
Vitamins are necessary for many bodily functions, including growth, development, healing, vision, and reproduction. Most vitamins are considered essential because they are not manufactured by the body and must be ingested in the diet. Vitamin D is also manufactured through exposure to sunlight. Vitamin toxicity can be caused by overconsumption of certain vitamins, such as vitamins A, D, C, B6, and niacin. Conversely, vitamin deficiencies can be caused by various factors including poor food intake due to poverty, malabsorption problems with the gastrointestinal tract, drug and alcohol abuse, proton pump inhibitors, and prolonged parenteral nutrition. Deficiencies can take years to develop, so it is usually a long-term problem for patients.
Vitamins are classified as water soluble or fat soluble. Water-soluble vitamins are not stored in the body and include vitamin C and B-complex vitamins: B1 (thiamine), B2 (riboflavin), B3 (niacin), B6 (pyridoxine), B12 (cyanocobalamin), and B9 (folic acid). Additional water-soluble vitamins include biotin and pantothenic acid. Excess amounts of these vitamins are excreted through the kidneys in urine, so toxicity is rarely an issue, though excess intake of vitamin B6, C, or niacin can result in toxicity.
Fat-soluble vitamins are absorbed with fats in the diet and include vitamins A, D, E, and K. They are stored in fat tissue and can build up in the liver. They are not excreted easily by the kidneys due to storage in fatty tissue and the liver, so overconsumption can cause toxicity, especially with vitamins A and D.
Minerals
Minerals are inorganic materials essential for hormone and enzyme production, as well as for bone, muscle, neurological, and cardiac function. Minerals are needed in varying amounts and are obtained from a well-rounded diet. In some cases of deficiencies, mineral supplements may be prescribed by a health care provider. Deficiencies can be caused by malnutrition, malabsorption, or certain medications, such as diuretics.
Minerals are classified as either macrominerals or trace minerals. Macrominerals are needed in larger amounts and are typically measured in milligrams, grams, or milliequivalents. Macrominerals include sodium, potassium, calcium, magnesium, chloride, and phosphorus. Trace minerals are needed in tiny amounts. Trace minerals include zinc, iron, chromium, copper, fluorine, iodine, manganese, molybdenum, and selenium.
Nutritional Guidelines
Nutritional guidelines are developed by governmental agencies to provide guidance to the population on how to best meet nutritional needs. These guidelines may vary by country. The National Academies of Sciences, Engineering, and Medicine set the Dietary Reference Intakes (DRIs) for the United States and Canada. Dietary Reference Intakes (DRIs) are a set of reference values used to assess and plan nutrient intakes for healthy people.
Nutrition Assessment of Individuals
A comprehensive nutrition assessment is essential for identifying individuals at risk of malnutrition or those with specific dietary needs.
Malnutrition: Undernutrition vs. Overnutrition
Malnutrition encompasses both undernutrition and overnutrition. Undernutrition results from a deficiency of nutrients, while overnutrition results from an excess of nutrients relative to energy expenditure.
Diet-Planning Guides
Diet-planning guides provide frameworks for individuals to make informed food choices and achieve balanced nutrient intakes.
Medical Nutrition Therapy
Medical nutrition therapy (MNT) is a therapeutic approach to treating medical conditions and their associated symptoms through the use of a specifically tailored diet devised and monitored by a registered dietitian or other nutrition professional. It involves:
- Nutrition assessment: Learning about a person's nutritional needs.
- Nutrition diagnosis: Identifying a nutrition-related issue to address.
- Nutrition intervention: Creating a plan and explaining what the person needs to do.
- Nutrition monitoring and evaluation: Checking on how things are going and changing the plan as needed.
Steps for Medical Nutrition Therapy
Dietitians generally follow these steps for medical nutrition therapy:
- Nutrition assessment: The dietitian reviews the patient's medical history and test results and talks to the patient to learn more about their needs, goals, and preferences. They may ask about foods the patient typically eats, any allergies or intolerances, lifestyle or cultural factors that influence how and what they eat, and any challenges they face in accessing or preparing foods.
- Nutrition diagnosis: The dietitian identifies a nutrition-related issue to focus on treating. This is different from a medical diagnosis and typically relates to the patient's intake of certain nutrients. For example, the patient may be taking in too much or not enough of a certain nutrient, like carbohydrates. The dietitian will identify the root cause of the issue as well as signs (like lab results) and symptoms (like gas and gas pain).
- Nutrition intervention: Based on the assessment and diagnosis, the dietitian creates a plan that addresses the nutrition-related issue. The dietitian will discuss the patient's role in the plan, including changes to make in their daily life. They'll also tell the patient what meetings they can expect, including individual meetings with the dietitian and potentially group meetings. Virtual meetings (telehealth) may be an option in some cases.
- Nutrition monitoring and evaluation: Once the plan is in motion, the dietitian will do regular check-ins to see how things are going. They'll review test results, talk to the patient about how they're feeling, and consult with their other healthcare providers. If the patient feels something isn’t going well or has concerns, they should tell their dietitian, who will answer their questions and adjust the plan as needed.
The duration of medical nutrition therapy depends on the individual's situation and the condition they’re managing. It may last several months or years, and in some cases, it’s lifelong.