Carbohydrates: Structure and Sources
A carbohydrate is an organic compound (a substance that contains carbon bonded to hydrogen) that provides energy. Chemically, all carbohydrates contain carbon, hydrogen, and oxygen in the same proportion as water (H2O). A carbohydrate is measured in calories or “kilocalories.”
A kilocalorie (C) is a unit of energy. Note the capital C means these are kilocalories and not calories. Carbohydrates provide 4 Calories/gram and are an immediate source of energy for the body. For example, to find the number of carbohydrate kilocalories, find the amount of carbohydrates per serving and multiply this number by four to get the amount of carbohydrate kilocalories. Example: 20g carbohydrates x 4 = 80 kilocalories of carbohydrates. So keep this in mind when teaching clients.
Carbohydrates include starches, fiber, and sugars (glucose). Carbohydrates can be found in rice, pasta, cereals, starchy vegetables (corn, potatoes, green beans) and bread. Fiber-rich carbohydrates include berries, kidney beans, and broccoli. Carbohydrates with a large amount of sugars are baked goods, cookies, cakes, soda, syrups, and honey. You can think of carbohydrates as anything with “white” ingredients (white flour, white sugar). Fruits are also considered carbohydrates with sugar as well as alcohol. This is helpful to remember when conducting client teaching. You help them to distinguish between high calorie, high starch, and high sugar carbohydrates.
Carbohydrates: Role in the Body and Health Effects
The number one role carbohydrates play is to supply energy (4 C/gram). Carbohydrates are specifically important to neurologic function (brain) and physical exercise. Also, carbohydrates save protein use in the body by using carbohydrates for energy rather than growth and maintenance of body tissues and prevent ketosis. Growth and maintenance of body tissues is best done by proteins. Carbohydrates provide fiber from whole grains. Fiber reduces the risk of obesity, heart disease, type 2 diabetes, and high cholesterol. Fiber is needed to prevent constipation which can lead to hemorrhoids, and gastrointestinal disorders such as diverticulosis and colon cancer. Our bodies need 45-65% carbohydrate intake of our total energy intake (the Acceptable Macronutrient Distribution Range or AMDR). Adequate Intake of fiber is 25 grams per day for women and 38g for men.
An important point for nurses to remember about carbohydrates is that a low carbohydrate high protein diet can lead to keto-acidosis and damage to the heart, liver, and kidneys because the body will break down proteins (and muscle) if there is not enough glucose in the body for energy. Another important point is that the liver converts all molecules to glucose. So for those diabetic clients on oral anti-diabetic medications, always consider liver function. Hypoglycemia is another disease process to recognize concerning carbohydrates. Lastly, lactose intolerance is considered when discussing carbohydrates because dairy products contain lactose, a sugar and form of carbohydrates.
Lipids: Structure and Sources
A lipid is also an organic compound that provides an important energy source during rest and low intensity exercise. Chemically all fats contain carbon, hydrogen, and oxygen much less proportionately to water. A lipid also contains phospholipids, phosphorus, and occasionally nitrogen. Lipids include triglycerides, phospholipids, and sterols. Lipids are insoluble in water. Think of a lipid when making a salad dressing; the oil or fat stays on top of the water.
Lipids provide 9 Calories/gram and are a later source of energy for the body after carbohydrate calories have been used. Lipids contain the most concentrated amount of energy for the body. To find the number of lipid kilocalories, find the amount of fats per serving and multiply this number by nine to get the amount of fat kilocalories. For example, 20g fat x 9 = 180 kilocalories of fats.
Food sources include: oils, shortening, butter, margarine, mayonnaise, salad dressings, table cream, and sour cream. Triglycerides are the most common form of fats found in foods and contain fatty acids. Some fatty acids increase the risk of chronic disease and some fatty acids prevent disease and protect our health. Phospholipids contain phosphate and are found in only a few foods. Cholesterol is an example of a phospholipid. Cholesterol is found in any animal product. If it comes from an animal and has fat, it is cholesterol. Meat, eggs, dairy, and eggs are all examples of foods that contain cholesterol.
Lipids: Role in the Body and Health Effects
Lipids carry important fat soluble vitamins A, D, E, and K. They also provide a sense of fullness and satisfaction since they take longer to digest. There are three types of triglycerides and are important to distinguish because of their health effects. Saturated fatty acids (coconut oil, butter, cheese, whole milk, cream, lard, and beef fat) can cause high cholesterol, heart disease, and atherosclerosis, and contribute to obesity since fat is stored in adipose tissue. But Mono and Poly unsaturated fats such as olive oil, nuts, canola oil, corn, and safflower oils help prevent high cholesterol. Therefore, animal fats are saturated and contribute to high cholesterol, cardiovascular disease, and cancer, while plant fats are good and help lower the risk of disease. Also, saturated fats are solid at room temperature, while unsaturated fats are liquid at room temperature. This is an important point when teaching clients about fat in the diet. Essential fatty acids cannot be synthesized by the body and must be consumed in the diet (linoleic acid and alpha-linolenic acid).
There is one exception to the saturated fat classification, coconut oil. In years past, coconut oil was viewed as an artery clogging fat and placed in the same category as animal fat. When reexamined by experts this medium chain fatty acid is now seen as a heart healthy fat that fights disease. This fat is not stored in the body as adipose tissue, but rather metabolized by the liver immediately and used as energy. For this reason, experts say it speeds up metabolism and promotes weight loss. This beneficial oil is involved in research around the globe for medical conditions such as Alzheimer’s, Diabetes Mellitus Types I and II, Coronary Artery Disease, and numerous skin disorders.
An important point to know about lipids is to be aware of what cholesterol numbers mean. See http://www.cdc.gov/cholesterol/ldl_hdl.htm and review the National Lipid Association recommendations for patient-centered management of dyslipidemia: Part 1 – executive summary http://www.lipidjournal.com/article/S1933-2874(14)00274-8/fulltext#sec1.1
Proteins: Structure and Sources
A protein is also an organic compound that supports tissue growth, repair, and maintenance. Chemically all proteins contain carbon, hydrogen, and oxygen and differ from carbs and lipids in that they contain nitrogen. Proteins contain amino acids. The body will break down food proteins into amino acids and then rebuild the amino acids to build protein for the body, such as in the muscles and blood. Essential amino acids are only obtained from food, the body cannot make them. Non-essential amino acids are made by the body and do not need to be consumed in the diet. Proteins provide 4 Calories/gram for energy.
Food sources of proteins include: meat, poultry, fish, eggs, milk, yogurt, cheese, dried beans and peas, and nuts and nut butters. A small amount of protein can sometimes be found in whole grains and vegetables.
Proteins: Role in the Body and Health Effects
Proteins are essential for tissue growth, repair, and maintenance. A diet with the appropriate amount of protein promotes healing in any plan of care. If clients are not consuming enough carbohydrates and lipids, the body will use protein as an energy source. This can lead to problems such as poor healing, ketoacidosis, and muscle damage to include heart, kidneys, and liver. Protein can be used for energy in times of low carb intake and/or starvation. The body will break down protein for essential glucose to provide energy to the brain. Proteins have so many functions it is impossible to discuss them all. Here are the other functions to pay attention to in your readings: enzymes and hormones, maintaining fluid and electrolyte balance, acid-base balance, building a strong immune system, neurotransmission, and the transport and storage of other nutrients. Also the effects of consuming too much protein is not what you might think given many Americans think high protein diets are essential to weight loss and do not realize the health effects such as high cholesterol, bone loss, and kidney disease.
Note that according to the Institute of Medicine, a balanced diet will consist of between 20 to 35 percent calories from fat, 10 to 35 percent from protein and 45 to 65 percent from carbohydrates. Aim for 30 percent, 20 percent and 50 percent of your calories from fat, protein and carbohydrates, respectively.