Chemical substances that are necessary for growth, normal functioning, and maintaining life. These substances cannot be synthesized by the body and must be supplied by food. There are six basic groups of nutrients: carbohydrates, fats, proteins, vitamins, minerals, and water. Of these, only carbohydrates, fats, and proteins contain calories that provide the body with energy.
Having a body weight that is 10 percent greater than the standard for the person's age, height, and body type.
Excessive accumulation of fat in the body. Also, weight 20% higher than that considered desirable for the person's age, height, and bone structure.
A procedure that determines fat as a percentage of body weight, in which the thickness of a fold of skin measured with a caliper indicates the total percentage of fat.
Poor nutrition caused by poor diet or by poor utilization of food that may result from an unbalanced, insufficient, or excessive diet.
The use of food as fuel, resulting in the generation of energy and growth and the elimination of waste.
Commonly known as a calorie and also referred to as a "large calorie," which is equivalent to 1000 "small calories." One kilocalorie is the amount of energy needed to raise the temperature of 1 kg of water by 1° C. Calories measure the amount of energy a food produces in the body.
Also called caloric density, the number of calories in food. Energy value is determined by the types and amounts of nutrients each food contains.
Water has no caloric value but contributes about 65% of an individual's body weight, helps maintain fluid balance, dissolves chemicals and nutrients, transports nutrients, lubricates, aids in digestion, flushes out wastes, and regulates body temperature through perspiration.
Amount of water in human cells
Water is the largest single component of the body. Metabolically active cells of the muscle and viscera have the highest concentration, and calcified tissue cells the lowest. Total body water is higher in athletes than in nonathletes and decreases significantly with age because of diminished muscle mass.
Amount of water needed
On average, people should drink 6 to 8 glasses (48 to 64 ounces, or 3 to 4 pints) of water a day to maintain a healthy water balance.
Water intake is controlled mainly by thirst. Thirst control centers are located in the hypothalamus.
Absorption of water
Water is ingested as fluid and also as part of ingested food. Water is absorbed rapidly because it moves freely through membranes, mainly by diffusion.
Water loss normally occurs through the kidneys in urine, through the gastrointestinal tract in the feces, through the lungs in expired air, and through the skin in sweat that evaporates from the skin. The amount of water taken in daily is approximately equivalent to the amount lost.
Effects of water loss
The loss of 20% of body water may cause death, and the loss of only 10% causes severe disorders. In moderate weather, adults can live up to 10 days without water; children can live up to 5 days. By contrast, it is possible to survive without food for several weeks.
Excessive loss of body water that usually is accompanied by electrolyte balance changes.
The presence of excess water that causes cells, particularly brain cells, to swell, leading to headache, nausea, vomiting, convulsion, and death. Water intoxication may result from the excessive administration of water when the antidiuretic hormone and the kidney cannot respond, such as after surgery, trauma, or another condition that causes salt and water loss.
The body's primary source of energy. Carbohydrates provide heat, help metabolize fat, and help reserve protein for uses other than supplying energy. One gram of carbohydrate yields 4 calories. Excess carbohydrates are stored in the liver and muscles as glycogen.
A complex carbohydrate that is a major source of energy from plant foods.
A nondigestible carbohydrate found in plant cells. It provides bulk and stimulation for the intestines. The main dietary fiber components are cellulose, pectin, lignin, and gums. Some forms are soluble in water; others are not. Dietary fiber is used to treat and prevent constipation, hemorrhoids, diverticular disease, and irritable bowel syndrome.
Also called lipids, fats are not soluble in water but are soluble in some solvents such as alcohol. They provide energy and heat, carry fat-soluble vitamins, protect and support organs and bones, insulate from cold, and supply essential fatty acids. Each gram of fat provides 9 calories. Fats are classified as saturated or unsaturated; unsaturated fats are either monounsaturated or polyunsaturated.
Fats generally derived from animal sources and usually solid at room temperature. Found in meat, butter, egg yolks, whole milk, and coconut and palm oil, they tend to raise blood cholesterol levels.
Fats that are usually liquid at room temperature and can be monounsaturated or polyunsaturated. They tend to lower blood cholesterol levels.
Examples include oil from olives, avocados, or cashew nuts.
Examples include cooking oils made from sunflower seeds, peanuts, or safflower seeds.
Chemical substances that are broken down by fatty acids in the liver.
The abnormal collection of ketones in the blood as a result of excessive breakdown of fats caused by an insufficiency of glucose available for energy.
A waxy lipid found almost exclusively in foods of animal origin and continuously synthesized in the body. Produced by the liver, cholesterol is essential for the production of vitamin D and bile acid. Because the body produces cholesterol, it is not essential in the diet. Cholesterol is measured by means of a blood test.
High-density lipoprotein (HDL)
Called "good" cholesterol. It helps transport cholesterol to the liver where it is disposed. It may serve to stabilize very low-density lipoprotein.
Low-density lipoprotein (LDL)
Called "bad" cholesterol. A high concentration may result in atherosclerosis and thus puts patients at risk of heart disease.
The presence of an excessive amount of cholesterol in the blood. To reduce cholesterol level, individuals should reduce fat consumption to less than 30% of total caloric intake, with saturated fats providing less than 10% of caloric intake, and should increase consumption of soluble fiber.
One of several combinations of fatty acids and glycerol that circulate in the blood with HDL and LDL. High levels are associated with atherosclerosis.
150-200 mg/dl; HDL: 25-90 mg/dl; LDL: 85-200 mg/dl; Glucose 90-120 mg/dl; Iron 50-175 μ g/dl; Triglycerides; 200-300 mg/dl
The primary function of protein is to build and repair body tissues. It is the only substance that can make new cells and rebuild tissue. Proteins are also important components of hormones and enzymes. They maintain fluid balance, are essential for the development of antibodies, and can provide energy. Each gram of protein provides 4 calories of energy. Proteins are not as efficient as carbohydrates and fats in providing energy.
Nitrogen-containing compounds that make up proteins, also called the building blocks of protein.
Amino Acids Essential
Arginine (in young children), Histidine ,Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine
Amino Acids Nonessential
Alanine, Arginine (in adults), Asparagine, Aspartic acid, Cysteine, Glutamic acid, Glutamine, Glycine, Proline, Serine, Tyrosine
Classification of amino acids
There are about 80 amino acids, of which 20 are necessary for human metabolism and growth. The adult body does not produce nine of them, which must be provided in the diet and are known as essential amino acids.
A protein that contains all the essential amino acids and consequently is of high biological value. Casein (milk protein) and egg whites are examples of complete proteins.
Sources of protein
Meat, fish, poultry, eggs, and milk, which are complete proteins, and nuts, dry beans, grains, and vegetables, which are incomplete proteins.
Adequate protein intake
Learning to combine foods containing incomplete proteins in order to obtain all nine essential amino acids is especially important for people who follow vegetarian diets.
An organic compound that does not provide energy but helps in the metabolism of protein, carbohydrates, and fat. Vitamins act as catalysts and body regulators for the bones, skins, glands, nerves, brain, and blood, and they protect against diseases caused by nutritional deficiencies. There are two types of vitamins: water-soluble and fat-soluble.
Classification of Vitamins: Water-Soluble Vitamins
Vitamin B complex:
Thiamine (Vitamin B1)
Riboflavin (Vitamin B2)
Niacin (Vitamin B3)
Pyridoxine (Vitamin B6)
Folic acid (Vitamin B9)
Cyanocobalamin (Vitamin B12)
Biotin (formerly vitamin H)
Classification of Vitamins: Fat-Soluble Vitamins
Vitamin A; Vitamin D; Vitamin E; Vitamin K
Vitamin B1 (thiamine)
Plays a role in carbohydrate metabolism and is essential for normal metabolism of the nervous system, heart, and muscles. Thiamine also promotes good appetite. It is not stored in the body and must be supplied daily. Sources include lean pork, wheat germ, lean meat, egg yolk, and fish.
Vitamin B2 (riboflavin)
Is essential for certain enzyme systems in the metabolism of fats and proteins. It can be sensitive to light. Sources include milk, cheddar cheese, cottage cheese, organ meats, and eggs. Deficiency causes impaired growth, weakness, lip sores and cracks at the corners of the mouth, cheilosis, photophobia, cataracts, anemia, and glossitis.
Vitamin B3 (niacin)
Part of two enzymes that regulate energy metabolism. Also called nicotinic acid and nicotinamide, it maintains the health of the skin, tongue, and digestive system. Sources include lean meats, poultry, fish, and peanuts. Deficiency causes pellagra, gastrointestinal disturbance, and mental disturbances.
Vitamin B6 (pyridoxine)
Aids enzymes in the synthesis of amino acids and is essential for proper growth and maintenance of body functions. Sources include yeast, wheat germ, pork, bananas, and oatmeal. Deficiency causes anemia, neuritis, anorexia, nausea, depressed immunity, and dermatitis.
Vitamin B9 (folic acid)
Is essential for cell growth and the reproduction of RBCs. Also called folacin, it functions in the formation of hemoglobin and aids in metabolism of protein. It is also essential for fetal development, particularly of the neural tube. Sources include liver, kidney beans, lima beans, and fresh dark green leafy vegetables. Deficiency causes anemia and may cause spina bifida in a fetus.
Vitamin B12 (cyanocobalamin)
Aids in hemoglobin synthesis, is essential for normal functioning of all cells, and is important in energy metabolism. Sources include liver, kidney, milk, eggs, fish, and cheese. Deficiency causes pernicious anemia and neurological disorders.
A part of the vitamin B complex that is essential for fatty acid metabolism, the manufacture of sex hormones, the utilization of other vitamins, the functioning of the nervous system and the adrenal glands, and normal growth and development. Sources include egg yolks, kidney, liver, and yeast. Deficiency causes fatigue, headaches, nausea, abdominal pain, numbness, tingling, muscle cramps, and susceptibility to respiratory infections and peptic ulcers.
Biotin (formerly vitamin H)
A water-soluble B-complex vitamin essential for the breakdown of fatty acids and carbohydrates and for the excretion of the waste products of protein breakdown. Good sources include kidney, liver, egg yolks, soybeans, and yeast.
Also called ascorbic acid, it protects the body against infections and helps heal wounds. Best sources are fruits and vegetables, especially citrus fruits and tomatoes. Deficiency causes scurvy, lowered resistance to infections, joint tenderness, dental caries, bleeding gums, delayed wound healing, bruising, hemorrhage, and anemia. Vitamin C is lost in cooking fresh foods but not in cooking frozen foods.
Vitamin A (retinol, carotene)
Contributes to the maintenance of epithelial cells and mucous membranes and is important for night vision. Retinol is also necessary for normal growth, development, and reproduction as well as an adequate immune response. Sources include liver, beef, sweet potato, spinach, milk, and egg yolks.
Is essential for the normal formation of bones and teeth. It aids in the reabsorption of calcium and phosphorus and regulates blood levels of calcium. There are two major forms of vitamin D: vitamin D2, formed in plants, and vitamin D3, formed in humans from cholesterol in the skin exposed to sunlight or other ultraviolet radiation. Best sources are butter, cream, egg yolks, liver, and fish liver oils. Deficiency causes rickets and osteomalacia.
An antioxidant, also called tocopherol. It prevents oxidative destruction of vitamin A in the intestine, and it is essential for normal reproduction, muscle development, and resistance of RBCs to hemolysis. Vitamin E also helps maintain normal cell membranes. Sources include seed oil, fruits, vegetables, and animal fats.
Is essential to blood clotting. There are several fat-soluble compounds of vitamin K. Vitamin K2 is synthesized in the intestine by bacteria and is also found in animal foods. Vitamin K is found in large amounts in green leafy vegetables (especially broccoli, cabbage, and lettuce) and in fruits. Vitamin K can be used as an antidote for an overdose of an anticoagulant. Deficiency causes hemorrhage.
Deficiency of vitamins in the diet that causes a disease such as scurvy, rickets, or beriberi.
A condition caused by an overdose of vitamins, especially fat-soluble vitamins. The main symptoms are loss of hair, severe itching, skin lesions, and abnormal tissue growth.
Excessive intake of vitamin A
Can result in a condition called hypervitaminosis A, the symptoms of which include headache, tiredness, nausea, loss of appetite, diarrhea, dry and itchy skin, hair loss, a yellow discoloration, and irregular menstrual periods. Excessive intake during pregnancy may cause birth defects.
Excessive intake of vitamin B6
May cause neuritis.
Natural, inorganic substances that the body needs to help build and maintain body tissues and to carry on life functions. There are two separate classes of minerals: major minerals and trace elements.
Compounds, particularly salts, that break up into their separate component particles in water. The particles are called ions, which are electrically charged atoms. Sodium, potassium, and chloride are commonly called electrolytes. Minerals help keep the body's water and electrolytes in balance.
The body requires calcium for the transmission of nerve impulses, muscle contraction, blood coagulation, and cardiac functions. Calcium also helps build strong bones and teeth and may prevent hypertension. Normal daily requirement: 800-1200 mg. The following factors enhance the absorption of calcium: adequate vitamin D, large quantities of calcium and phosphorus in diet, and the presence of lactose. A lack of physical activity reduces the amount of calcium absorption.
Essential for the metabolism of protein, calcium, and glucose. It helps to build strong bones and teeth and aids in maintaining the body's acid-base balance. Phosphorus is found in dairy foods, animal foods, fish, cereals, nuts, and legumes.
Involved in the maintenance of fluid and the body's acid-base balance. Disturbances in the acid-base balance can result in possible growth retardation and memory loss.
Plays a key role in the maintenance of the body's acid-base balance. It transmits nerve impulses and helps control muscle contractions. Toxic levels may cause hypertension and renal disease. The kidney is the chief regulator of sodium levels in body fluids.
Important in protein synthesis, correction of imbalance in acid-base metabolism, and glycogen formation. It transmits nerve impulses and helps control them. It also promotes regular heartbeat and is needed for enzyme reactions.
Helps build strong bones and teeth and activates many enzymes. It helps regulate heartbeat and is essential for metabolism and many enzyme activities. It is stored in bone and is excreted mainly by the kidneys.
A component of the thyroid hormone thyroxine. Iodine is also used as a contrast medium for blood vessels in CT scans.
Essential for several enzymes, growth, glucose tolerance, wound healing, and taste acuity. Best sources are protein foods.
A component of hemoglobin and myoglobin. The major role of iron is to deliver oxygen to the body tissues.
Ferrous sulfate (Feosol)
The most inexpensive and most commonly used form of iron supplement.
Iron dextran (Imferon)
An injectable form of iron supplement.
Excessive absorption of iron.
An element most concentrated in the liver, heart, brain, and kidneys. It is essential for several important enzymes and for good health. It aids in the formation of hemoglobin. Copper helps in the transportation of iron to bone marrow.
A hereditary disease that causes copper accumulation in various organs and can result in degeneration of the brain, cirrhosis of the liver, psychic disturbances, and progressive weakness.
An element that increases resistance to tooth decay. It protects against osteoporosis and periodontal (gum) disease. Excessive amounts of fluoride in drinking water may cause the discoloration of teeth.
Developed by the U.S. Department of Agriculture and the U.S. Department of Health and Human Services, recommendations to encourage people to eat a balanced diet.
Also referred to as medical nutrition therapy or a therapeutic diet. It may be necessary in order to maintain or improve nutritional status; to correct nutritional deficiencies; to maintain, decrease, or increase body weight; or to eliminate particular foods that may cause allergies.
Nutrition during pregnancy
The protein requirement is increased by 20% for pregnant women. An increase is also recommended in calcium, iron, and folic acid intake. The average energy allowance during the first trimester is 2200 Kcal per day. Lactating women during the first 6 months need 2700 Kcal per day. Doctors recommend that pregnant women gain from 24 to 35 pounds during their pregnancy.
The mother's milk provides the infant with temporary immunity to many infectious diseases. It is free from germs and is easy to digest. It usually does not cause allergic reactions. Breastfeeding also stimulates an emotional bond between mother and infant. The American Academy of Pediatrics recommends breastfeeding for at least 1 year, and the World Health Organization recommends 2 years. In most cases breastfeeding is the best source of milk for a growing child.
Mechanical soft diet
A diet that consists of soft but otherwise normal foods. It is used by individuals who have difficulty chewing because of a lack of dentures or teeth, inflammation of the oral cavity, or severe dental decay that may cause pain in chewing.
A diet used by individuals who cannot tolerate solid foods or by patients whose gastrointestinal tract must be free of solid foods. The diet consists of tea, coffee, cream soups, fruit juices, clear broths, and eggnog.
A diet used for patients with indications such as esophageal obstruction, burns, gastric surgery, or anorexia nervosa.
A diet that is nonirritating to the gastrointestinal tract. It is often prescribed in the treatment of peptic ulcer, ulcerative colitis, gallbladder disease, diverticulitis, and gastritis. This diet consists of milk, cream, mashed potatoes, and hot cereal.
A diet that may be prescribed for atonic constipation, diverticulosis, therapy of gastric ulcers, cancer of the colon, hypercholesterolemia, diabetes, or obesity.
A diet prescribed in the treatment of diabetes mellitus. It usually contains limited amounts of simple sugars and increased amounts of proteins, complex carbohydrates, and unsaturated fats. This diet is carefully calculated for each patient to minimize the occurrence of hyperglycemia and hypoglycemia, to maintain body weight, and to promote good health.
Dumping syndrome diet
A diet used for patients who have had a partial gastrectomy or gastric bypass surgery. This diet is low in concentrated sweets and limits fluids at mealtimes to avoid dumping the stomach contents into the small intestine, which results in diarrhea.
A diet used for patients with diseases of the liver, gallbladder, and pancreas. Generally 40 to 50 grams of fat per day is an adequate and realistic restriction.
A diet often recommended for patients with elevated blood cholesterol levels, those with atherosclerosis, and those with elevated triglycerides and low HDL-cholesterol.
A diet that may be indicated for purposes of weight gain. Ideally, the fat should be monounsaturated. The maximum fat intake is generally 35% to 40% of kilocalories.
A diet that is very common for patients with hypertension, renal disease with edema, congestive heart failure, and cirrhosis of the liver with ascites.
A diet that may be useful in treating Addison's disease.
A diet that may be necessary for patients with renal disease.
A diet used for patients who are on diuretics. Sources of potassium in the diet are whole grains, meat, legumes, fruit (bananas), and vegetables.
A diet to treat iron-deficiency anemia.
High-calcium and high-phosphorus diets
An increase in calcium and phosphorus intake is desirable in a patient with rickets, osteomalacia, tetany, dental caries, or acute lead poisoning.
A diet to treat Wilson's disease, oliguria, and anuria.
An illness usually caused by human ignorance or carelessness. Food is generally contaminated with harmful microorganisms or chemical poisons. The most common food illnesses are caused by Salmonella bacteria, Clostridium perfringens, Staphylococcus aureus, botulism, trichinosis, and protozoa.
Infestation with the parasitic roundworm Trichinella spiralis. It is transmitted by eating raw or undercooked pork from infected pigs.
Caused by the toxin produced by the spores of the Clostridium botulinum bacterium. It is the most deadly of all food poisonings. Home-canned foods are generally the source of botulism. It is characterized by fatigue and muscle weakness, visual disturbances, and dysphagia. The antitoxin must be administered as soon as possible.
Usually develop as a reaction to proteins. Allergies to specific substances are not inherited, but the tendency to develop allergies is inherited. Allergic individuals seem most prone to allergic reactions during periods of stress.
An eating disorder in which people starve themselves because they fear that otherwise they will become grossly overweight. It is most common among women in their teens and early 20s.
An eating disorder in which people eat a large amount of food in a short time, then attempt to counter the effects by self-induced vomiting, the use of laxatives or diuretics, and/or excessive exercise.
Eating a large amount of food in a short time without subsequent purging.