LVN Chapter 19 - Basic Nutrition Study Guide

Essential Nutrients and Body Functions

A nutrient is defined as a chemical compound or element found in food that is necessary for maintaining good health. These substances perform three major functions within the body: providing energy, building and repairing tissue, and regulating various body processes. Essential nutrients are those which the body cannot manufacture on its own in amounts sufficient for maintaining health, meaning they must be obtained through the diet. There are six specific essential nutrients required by the body: carbohydrates, fats (lipids), proteins, vitamins, minerals, and water.

Carbohydrates: Classification and Dietary Fiber

The primary function of carbohydrates is to provide energy to the body. Maintaining an adequate intake of carbohydrates is crucial for protein sparing, which ensures that protein is not diverted from its primary tissue-building roles to be used as an energy source. Carbohydrates are categorized into simple and complex forms.

Simple carbohydrates include monosaccharides and disaccharides. Monosaccharides consist of a single unit of sugar and require no digestion, allowing them to be absorbed directly into the bloodstream. Examples include glucose and the natural sugars found in fruit. Disaccharides are composed of two units of sugar, with common examples being table sugar and the sugar found naturally in milk. Simple carbohydrates are characterized as being easier to break down, though refined or simple sugars often possess low nutritional value.

Complex carbohydrates, also known as polysaccharides, are comprised of long chains of glucose units. Because of their structure, they are harder and slower for the body to break down. Starch is a complex carbohydrate that provides a sustained release of energy over a longer period. Dietary sources of starch and complex carbohydrates include grains, legumes, vegetables, corn, potatoes, and various plants. Glycogen, often referred to as animal starch, is the storage form of carbohydrates in humans. It is primarily stored in the liver and is called upon for use when blood glucose levels become low.

Dietary fiber consists of food material that humans are unable to digest or break down. Insoluble fiber does not dissolve in water; it serves to add bulk to the stool and accelerates the movement of waste through the digestive tract. Soluble fiber dissolves in water and acts to slow down the digestion process. The recommended daily intake for dietary fiber is between $25$ and $38\,g/day$. It is important to note that increasing fiber intake too rapidly can lead to adverse effects such as bloating, gas, and constipation.

Fats and Lipids

Fats, or lipids, are organic substances of a fatty nature that are insoluble in water. They provide the most concentrated source of energy compared to all other nutrients. In addition to energy, fats serve as insulation against extreme temperatures and act as a cushion to protect internal organs and tissues. For fats to be properly digested, they must be emulsified by bile. The vitamins A, D, E, and K are fat-soluble and require the presence of lipids for absorption.

Fatty acids are classified based on their chemical structure. Saturated fatty acids have no double bonds and are completely saturated with hydrogen. These are generally solid at room temperature and are found in foods such as butter, fatty meats, and coconut oil. High consumption of saturated fats is associated with increased blood cholesterol and a higher risk of atherosclerosis. Unsaturated fatty acids contain one or more double bonds where hydrogen is missing from parts of the chemical chain. These are typically liquid at room temperature and are often derived from plant sources like olive oil, avocados, nuts, seeds, and fish. In moderate amounts, these maintain a healthy profile and have a cholesterol-lowering effect. Trans-fatty acids are unsaturated fatty acids with a different chemical configuration produced during the hydrogenation of oils. Found in deep-fried and packaged foods, these are considered bad fats and should be avoided.

Cholesterol is a waxy sterol found in animal-based foods and within body cells. It serves as an essential building block for cell membranes and the production of hormones. While obtained through diet, it is also synthesized by the liver. Additionally, cholesterol plays a functional role in the process of digestion.

Proteins and Amino Acids

Proteins provide the essential building blocks for blood and bone. They are vital for tissue growth, repair, and the healing of wounds. Chemically, proteins are composed of carbon, hydrogen, and oxygen, along with nitrogen. The building blocks of protein are amino acids. Proteins are categorized as complete or incomplete based on their amino acid profile.

Complete proteins contain all nine essential amino acids required by the body and are typically found in animal sources such as meat, poultry, fish, milk, and eggs. Incomplete proteins lack one or more of these nine essential amino acids. Examples of incomplete proteins include nuts, seeds, grains, and legumes.

Vitamins and Their Specific Roles

Vitamins support metabolism, growth, and the general maintenance of the body. They are divided into water-soluble and fat-soluble categories. The water-soluble vitamins include the B-complex group and Vitamin C. The fat-soluble vitamins are A, D, E, and K.

Vitamin C, also known as ascorbic acid, contributes significantly to the healing of wounds, burns, and fractures. It is essential for the proper functioning of the adrenal glands and enhances the absorption of iron in the body. A deficiency in Vitamin C can lead to various health issues, including swollen gums, scurvy, and the opening of previously healed wounds.

Vitamin K is primarily recognized for its essential role in blood clotting. Vitamin D is necessary for the absorption of calcium and phosphorus, which directly supports the health and maintenance of bones and teeth.

Minerals and Electrolyte Balance

Minerals help regulate body functions and are incorporated into physical structures, contributing to the formation of enzymes, hormones, bones, skeletal tissue, teeth, and body fluids.

Potassium is a critical mineral with a normal serum range of $3.5$ to $5$. It is necessary for the conduction of nerve impulses and the contraction of muscles, including the heart muscle. It also regulates fluid and acid-base balance. Dietary sources of potassium include sweet potatoes, fruits, and vegetables. Calcium is vital for the formation of bones and teeth and is found in leafy greens and milk.

Sodium functions as an electrolyte and helps maintain fluid balance. It is common in salty and processed foods, and high intake is associated with hypertension and edema. Iron is a component of hemoglobin, which is the oxygen-carrying part of red blood cells, as well as myoglobin, an oxygen-storing protein in muscle cells. Iron is required for efficient oxygen transport, and a deficiency leads to anemia. The absorption of iron is enhanced by Vitamin C. Chromium is necessary for glucose metabolism and works in conjunction with insulin to regulate blood glucose levels. Sources of chromium include whole grains, liver, nuts, and cheese.

Water and Hydration

Water is the sixth essential nutrient and is critical for survival. It is required for maintaining fluid balance and facilitating normal body processes. Water aids in the transportation of substances throughout the body, regulates body temperature, and supports the elimination of waste products. Nursing assessment of a patient's hydration status typically involves monitoring intake and output, examining urine characteristics, checking mucous membranes, assessing for edema, and recording daily weights.

Questions and Discussion

Question: Name the 6 essential nutrients. Response: Carbohydrates, fats (lipids), proteins, vitamins, minerals, and water.

Question: What are the 3 major functions of nutrients? Response: To provide energy, build and repair tissue, and regulate body processes.

Question: What is the difference between simple and complex carbohydrates? Response: Simple carbohydrates (monosaccharides and disaccharides) require little to no digestion and are easier to break down, whereas complex carbohydrates (polysaccharides) are long chains of glucose that are harder and slower to break down, providing longer-lasting energy.

Question: What is the difference between soluble and insoluble fiber? Response: Insoluble fiber does not dissolve in water and adds bulk to stool to speed up movement; soluble fiber dissolves in water and slows down digestion.

Question: Which nutrient provides the most concentrated source of energy? Response: Fats (lipids).

Question: What are the differences among saturated, unsaturated, and trans fats? Response: Saturated fats have no double bonds, are usually solid, and increase cholesterol and atherosclerosis risk. Unsaturated fats have double bonds, are usually liquid, and are considered heart-healthy. Trans fats are hydrogenated oils with a different chemical structure and are considered bad for health.

Question: What are amino acids? Response: Amino acids are the building blocks of protein.

Question: What makes a protein complete? Response: A protein is complete if it contains all nine essential amino acids.

Question: Which vitamins are water-soluble? Which are fat-soluble? Response: Water-soluble vitamins are B and C. Fat-soluble vitamins are A, D, E, and K.

Question: What are the main functions of vitamins C, K, and D? Response: Vitamin C is for wound healing and iron absorption. Vitamin K is for blood clotting. Vitamin D is for calcium/phosphorus absorption and bone health.

Question: What is potassium needed for? Response: Potassium is needed for nerve impulses, muscle (including heart) contraction, and fluid/acid-base balance.

Question: What is iron used for, and what can iron deficiency cause? Response: Iron is used for hemoglobin and myoglobin to transport oxygen; a deficiency causes anemia.

Question: Which vitamin enhances iron absorption? Response: Vitamin C.