Glossary of Terms

ITG Program Glossary

Adrenal Glands (also known as suprarenal glands) are the triangle-shaped endocrine glands that sit on top of the kidneys; their name indicates that position (ad-, "near" or "at" + -renes, "kidneys"). They are chiefly responsible for regulating the stress response through the synthesis of corticosteroids and catecholamines, including cortisol and adrenaline.

Amino Acids are the building blocks of proteins. A protein forms via the condensation of amino acids to form a chain of amino acid "residues" linked by peptide bonds.  Proteins are defined by their unique sequence of amino acid residues; this sequence is the primary structure of the protein.  Just as the letters of the alphabet can be combined to form an almost endless variety of words, amino acids can be linked in varying sequences to form a huge variety of proteins.  When you eat foods that contain protein, the digestive juices in your stomach and intestine go to work.  They break down the protein in food into basic units, called amino acids. The amino acids then can be reused to make the proteins your body needs to maintain muscles, bones, blood, and body organs.

Autoimmunity is the failure of an organism to recognize its own constituent parts (down to the sub-molecular levels) as "self," which results in an immune response against its own cells and tissues.  Any disease that results from such an aberrant immune response is termed an autoimmune disease.  A prominent example includes diabetes mellitus type 1 (IDDM).

Blood Glucose is sugar in the blood that is used by the body cells for energy or stored as glycogen for future energy needs.

Blood Lipid is fat that is present in the blood, including triglycerides and cholesterol.

Blood sugar is a term used to refer to the amount of glucose in the blood. Glucose, transported via the bloodstream, is the primary source of energy for the body's cells.  Blood sugar concentration, or glucose level, is tightly regulated in the human body. Normally, the blood glucose level is maintained between about 4 and 8 mmol/L (70 to 150 mg/dL). The total amount of glucose in the circulating blood is therefore about 3.3g to 7g (assuming an ordinary adult blood volume of 5 liters). Glucose levels rise after meals and are usually lowest in the morning, before the first meal of the day.  Failure to maintain blood glucose in the normal range leads to conditions of persistently high (hyperglycemia) or low (hypoglycemia) blood sugar.  Diabetes mellitus, characterized by persistent hyperglycemia of several causes, is the most prominent disease related to failure of blood sugar regulation.  Although it is called "blood sugar," sugars besides glucose are found in the blood, such as fructose and galactose. Only glucose levels are regulated via insulin and glucagon.

Carbohydrates are found in a wide array of foods including but not limited to; bread, beans, milk, popcorn, potatoes, cookies, spaghetti, soft drinks, corn, and cherry pie. They also come in a variety of forms. The most common and abundant forms are sugars, fibers, and starches.  The basic building block of every carbohydrate is a sugar molecule, a simple union of carbon, hydrogen, and oxygen.  Starches and fibers are essentially chains of sugar molecules.  Some contain hundreds of sugars.  Some chains are straight, others branch wildly.  Carbohydrates were once grouped into two main categories.  Simple carbohydrates included sugars such as fruit sugar (fructose), corn or grape sugar (dextrose or glucose), and table sugar (sucrose).  Complex carbohydrates included everything made of three or more linked sugars.  Complex carbohydrates were thought to be the healthiest to eat, while sugars weren't so great.  It turns out that the picture is more complicated than that.  The digestive system handles all carbohydrates in much the same way—it breaks them down (or tries to break them down) into single sugar molecules, since only these are small enough to cross into the bloodstream.  It also converts most digestible carbohydrates into glucose (also known as blood sugar), because cells are designed to use this as a universal energy source.

Cell is the structural and functional unit of all known living organisms.  It is the smallest unit of an organism that is classified as living, and is sometimes called the building block of life.

Cholesterol is a waxy, fat-like substance produced by the liver and contained in selected foods (e.g., egg yolks, coconut oil).  Cholesterol is a form of lipid.  The body produces all the cholesterol it needs to function normally.  200mg/dl or less is the desired blood level.

Complex Carbohydrate (carbs) foods are basically those in wholegrain form such as wholegrain breads, oats, muesli and brown rice.  Complex carbs are broken down into glucose more slowly than simple carbohydrates and thus provide a gradual steady stream of energy throughout the day.  All carbohydrates are broken down to glucose to produce the energy molecule ATP (adenosinetriphosphate).  The efficiency of this whole process also depends on many vitamins and minerals.  Most natural, complex carbohydrate sources naturally provide many of the vitamins and minerals needed for energy production.  Simple, refined carbs found in many processed, convenient foods tend to be devoid of these natural nutrients, therefore there is a greater risk that some of the energy will be converted into fat and stored.  This is often the case even if the calorie content of the simple carb is lower than the calories in the complex carbohydrate source.  Natural complex carbs are often devoid of additives and preservatives unlike many processed simple carb sources.

Diabetes

Type 1 Diabetes:  Diabetes mellitus type 1 (Type 1 diabetes, Type I diabetes, T1D, IDDM) is a form of diabetes mellitus.  Type 1 diabetes is an autoimmune disease that results in the permanent destruction of insulin producing beta cells of the pancreas. Type 1 is lethal unless treatment with exogenous insulin via injections replaces the missing hormone.  Formerly known as "childhood", "juvenile" or "insulin-dependent" diabetes, it is not exclusively a childhood problem: the adult incidence of Type 1 is significant — many adults who contract Type 1 diabetes are misdiagnosed with Type 2 due to the misconception of Type 1 as a disease of children — and since there is no cure, Type 1 diabetic children will grow up to be Type 1 diabetic adults.  There is currently no preventive measure that can be taken against type 1 diabetes.  Most people affected by type 1 diabetes are otherwise healthy and of a healthy weight when onset occurs, but they can lose weight quickly and dangerously, if not diagnosed in a relatively short amount of time.  Diet and exercise cannot reverse or prevent type 1 diabetes.  However, there are clinical trials ongoing that aim to find methods of preventing or slowing its development.

Type 2 Diabetes Mellitus is often referred to as adult onset diabetes or noninsulin dependent diabetes mellitus.  This is a disease state in which glucose is not able to move efficiently from the blood to the cells.  There are two possible causes.  First, the pancreas produces enough insulin but the insulin is not effective in removing glucose from the blood.  Second, the pancreas eventually may not produce enough insulin to properly remove glucose from the blood.

Endocrine Glands are glands that secrete their product (hormones) directly into the blood rather than through a duct.  This group contains the glands of the Endocrine system. The main Endocrine glands include the pituitary gland, the pancreas, the gonads, the thyroid gland and the adrenal glands.  Other organs which are not so well known for their endocrine activity include the stomach, which produces such hormones as ghrelin.

Enzymes are proteins that catalyze (i.e. accelerate) chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, the products.  Almost all processes in a biological cell need enzymes in order to occur at significant rates.  Since enzymes are extremely selective for their substrates and speed up only a few reactions from among many possibilities, the set of enzymes made in a cell determines which metabolic pathways occur in that cell.

Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. Chemically, fats are generally triesters of glycerol and fatty acids.  Fats may be either solid or liquid at normal room temperature, depending on their structure and composition.  Although the words oils, fats, and lipids are all used to refer to fats, oils are usually used to refer to fats that are liquids at normal room temperature, while fats are usually used to refer to fats that are solids at normal room temperature. Lipids are used to refer to both liquid and solid fats.  The word oil is used for any substance that does not mix with water and has a greasy feel, such as petroleum (or crude oil) and heating oil, regardless of its chemical structure.  Fats form a category of lipid, distinguished from other lipids by their chemical structure and physical properties. This category of molecules is important for many forms of life, serving both structural and metabolic functions.  They are an important part of the diet of most heterotrophs (including humans).  Fats or lipids are broken down in the body by enzymes called lipase produced in the pancreas.

Fructose (also levulose or laevulose) is a simple reducing sugar (monosaccharide) found in many foods and is one of the three most important blood sugars along with glucose and galactose.  Honey, tree fruits, berries, melons, and some root vegetables, such as beets, sweet potatoes, parsnips, and onions, contain fructose, usually in combination with sucrose and glucose.  Fructose is also derived from the digestion of sucrose, a disaccharide consisting of glucose and fructose that is broken down by glycoside hydrolase enzymes during digestion.  Fructose is the sweetest naturally occurring sugar, estimated to be twice as sweet as sucrose.

Glands are organs in an animal's body that synthesizes a substance for release such as hormones or breast milk, often into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland).

Glucagon is an important hormone involved in carbohydrate metabolism.  Produced by the pancreas, it is released when the glucose level in the blood is low (hypoglycemia), causing the liver to convert stored glycogen into glucose and release it into the bloodstream.  The action of glucagon is thus opposite to that of insulin, which instructs the body's cells to take in glucose from the blood in times of satiation.

Gluconeogenesis is the generation of glucose from non-sugar carbon substrates like pyruvate, lactate, glycerol, and glucogenic amino acids.  The vast majority of gluconeogenesis takes place in the liver and, to a smaller extent, in the cortex of kidneys. This process occurs during periods of fasting, starvation, or intense exercise and is highly endergonic. Gluconeogenesis is often associated with ketosis.

Glucose is a simple sugar and an important carbohydrate in biology. The living cell uses it as a source of energy and metabolic intermediate. Glucose is one of the main products of photosynthesis and starts cellular respiration in both prokaryotes and eukaryotes. The name comes from the Greek word glykys (γλυκύς), which means "sweet", plus the suffix "-ose" which denotes a sugar.

Glycogen is a storage form for glucose in the body.  It is a polysaccharide of glucose (Glc) which functions as the primary short term energy storage in animal cells. It is made primarily by the liver and the muscles, but can also be made by the brain, uterus, and the vagina.  Only the glycogen stored in the liver can be made accessible to other organs. In the muscles, glycogen is found in a much lower concentration (1% of the muscle mass), but the total amount exceeds that in liver.  Small amounts of glycogen are found in the kidneys, and even smaller amounts in certain glial cells in the brain and white blood cells. The uterus also stores glycogen during pregnancy to nourish the embryo.

High Density Lipoprotein (HDL) is often referred to as the "good" cholesterol because it removes cholesterol from the bloodstream preventing it from accumulating in the vessels.

Low Density Lipoprotein (LDL) is often referred to as the "bad" cholesterol because it carries most of the cholesterol in the blood.  If the LDL level is too high, cholesterol and fat can build up in the arteries.

Hormone is a chemical messenger that carries a signal from one cell (or group of cells) to another via the blood.  All multi-cellular organisms produce hormones (including plants).  In general, hormones regulate the function of their target cells, i.e., cells that express a receptor for the hormone. The action, or net effect of hormones is determined by a number of factors including its pattern of secretion and the response of the receiving tissue - the signal transduction response.  Endocrine hormone molecules are secreted (released) directly into the bloodstream, while exocrine hormones (or ectohormones) are secreted directly into a duct, and from the duct they either flow into the bloodstream or they flow from cell to cell by diffusion in a process known as paracrine signalling.

Hyperglycemia, hyperglycaemia, or high blood sugar is a condition in which an excessive amount of glucose circulates in the blood plasma.  Hypoglycemia is the medical term for a pathologic state produced by a lower than normal level of glucose (sugar) in the blood.  The term hypoglycemia literally means "under-sweet blood."  Hypoglycemia can produce a variety of symptoms and effects but the principal problems arise from an inadequate supply of glucose as fuel to the brain, resulting in impairment of function (neuroglycopenia).  Derangements of function can range from vaguely "feeling bad" to coma and (rarely) permanent brain damage or death. Hypoglycemia can arise from many causes and can occur at any age.  Hypoglycemia, also called low blood sugar, occurs when your blood glucose (blood sugar) level drops too low to provide enough energy for your body's activities.  In adults or children older than 10 years, hypoglycemia is uncommon except as a side effect of diabetes treatment, but it can result from other medications or diseases, hormone or enzyme deficiencies, or tumors.  Glucose, a form of sugar, is an important fuel for your body.  Carbohydrates are the main dietary sources of glucose.  Rice, potatoes, bread, tortillas, cereal, milk, fruit, and sweets are all carbohydrate-rich foods.  After a meal, glucose molecules are absorbed into your bloodstream and carried to the cells, where they are used for energy.  Insulin, a hormone produced by your pancreas, helps glucose enter cells.  If you take in more glucose than your body needs at the time, your body stores the extra glucose in your liver and muscles in a form called glycogen.  Your body can use the stored glucose whenever it is needed for energy between meals.  Extra glucose can also be converted to fat and stored in fat cells.  When blood glucose begins to fall, glucagon, another hormone produced by the pancreas, signals the liver to break down glycogen and release glucose, causing blood glucose levels to rise toward a normal level.  If you have diabetes, this glucagon response to hypoglycemia may be impaired, making it harder for your glucose levels to return to the normal range.

Insulin is a hormone produced by the pancreas and is essential for proper use of glucose in the body.  It helps the body utilize blood glucose (blood sugar) by binding with receptors on cells like a key would fit into a lock.  Once the key insulin- has unlocked the door, the glucose can pass from the blood into the cell.  Inside the cell, glucose is either used for energy or stored for future use in the form of glycogen in liver or muscle cells.     … is an animal hormone whose presence informs the body's cells that the animal is well fed, causing liver and muscle cells to take in glucose and store it in the form of glycogen, and causing fat cells to take in blood lipids and turn them into triglycerides. In addition it has several other anabolic effects throughout the body.  Insulin is used medically to treat some forms of diabetes mellitus. Patients with type 1 diabetes mellitus depend on external insulin (most commonly injected subcutaneously) for their survival because of the absence of the hormone. Patients with type 2 diabetes mellitus have insulin resistance, relatively low insulin production, or both; some type 2 diabetics eventually require insulin when other medications become insufficient in controlling blood glucose levels.  Insulin is a peptide hormone composed of 51 amino acid residues and has a molecular weight of 5808 Da. It is produced in the Islets of Langerhans in the pancreas. The name comes from the Latin insula for "island.”

Insulin Resistance occurs when the normal amount of insulin secreted by the pancreas is not able to remove glucose from the blood into the cells for use as energy or storage for future use.  It occurs when the normal amount of insulin secreted by the pancreas is not able to unlock the door to cells.  To maintain a normal blood glucose, the pancreas secretes additional insulin.  In some cases (about 1/3 of the people with insulin resistance), when the body cells resist or do not respond to even high levels of insulin, glucose builds up in the blood resulting in high blood glucose or type 2 diabetes.  Even people with diabetes who take oral medication or require insulin injections to control their blood glucose levels can have higher than normal blood insulin levels due to insulin More and more people in the U.S. are becoming obese, physically inactive, or both.  Obesity and physical inactivity aggravate insulin resistance.  Also, people who are insulin resistant typically have an imbalance in their blood lipids (blood fat).  They have an increased level of triglycerides (blood fat) and a decreased level of HDL (good) cholesterol.  Imbalances in triglycerides and HDL cholesterol increase the risk for heart disease.  These findings have heightened awareness of insulin resistance and its impact on health.

Islets of Langerhans The endocrine (i.e., hormone-producing) cells of the pancreas are grouped in the islets of Langerhans. Discovered in 1869 by the German pathological anatomist Paul Langerhans, the islets of Langerhans constitute approximately 1 to 2% of the mass of the pancreas.  There are about one million islets in a healthy adult human pancreas, which are distributed evenly throughout the organ, and their combined weight is 1 to 1.5 grams.

Ketoacidosis should not be confused with Ketosis.  Ketoacidosis (diabetic ketoacidosis or the less common alcoholic ketoacidosis), is severe ketosis causing the pH of the blood to drop below 7.2.  Ketoacidosis is a medical condition usually caused by diabetes and accompanied by dehydration, hyperglycemia, ketonuria and increased levels of glucagon. The high glucagon, low insulin serum levels signals the body to produce more glucose via gluconeogenesis and glycogenolysis, and ketone bodies via ketogenesis.  High levels of glucose causes the failure of tubular reabsorption in the kidneys, causing water to leak into the tubules in a process called osmotic diuresis, causing dehydration and further exacerbating the acidosis.

Ketonic Bodies are three water-soluble compounds that are produced as by-products when fatty acids are broken down for energy in the liver and kidney.  They are used as a source of energy in the heart and brain.  In the brain, they are a vital source in fasting.

Ketosis merely means that our bodies are using fat for energy.  Ketones (also called ketone bodies) are molecules generated during fat metabolism, whether from the fat in the guacamole you just ate or fat you were carrying around your middle.  When our bodies are breaking down fat for energy, most of it gets converted more or less directly to ATP. (Remember high school biology? This is the energy molecule.) But ketones are also produced as part of the process.  When people eat less carbohydrate, their bodies turn to fat for energy, so it makes sense that more ketones are generated.

Kidneys are organs that filter wastes (such as urea) from the blood and excrete them, along with water, as urine.

Lipids are broadly defined as any fat-soluble (lipophilic), naturally-occurring molecules, such as fats, oils, waxes, cholesterol, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The main biological functions of lipids include energy storage, acting as structural components of cell membranes, and participating as important signaling molecules.  Although the term lipid is sometimes used as a synonym for fat, fats are in fact a subgroup of lipids called triglycerides and should not be confused with the term fatty acid. Lipids also encompass molecules such as fatty acids and their derivatives (including tri-, di-, and monoglycerides and phospholipids), as well as other sterol-containing metabolites such as cholesterol.  Lipids are an important part of living cells.  Together with carbohydrates and proteins, lipids are the main constituents of plant and animal cells.  Another word for "fats."  Lipids can be more formally defined as substances such as a fat, oil or wax that dissolves in alcohol but not in water.  Lipids contain carbon, hydrogen and oxygen but have far less oxygen proportionally than carbohydrates.  Lipids are an important part of living cells.  Together with carbohydrates and proteins, lipids are the main constituents of plant and animal cells.  Cholesterol and triglycerides are lipids. Lipids are easily stored in the body.  They serve as a source of fuel and are an important constituent of the structure of cells.

Liver:   The liver is an organ present in vertebrates and some other animals.  It plays a major role in metabolism and has a number of functions in the body, including glycogen storage, decomposition of red blood cells, plasma protein synthesis, and detoxification. This organ also is the largest gland in the human body.  It lies below the diaphragm in the thoracic region of the abdomen. It produces bile, an alkaline compound which aids in digestion, via the emulsification of lipids.  It also performs and regulates a wide variety of high-volume biochemical reactions requiring very specialized tissues.

Lypogenesis is the process by which glucose is converted to fatty acids, which are subsequently esterified to glycerol to form the triacylglycerols that are packaged in VLDL and secreted from the liver.  Lipogenesis encompasses the processes of fatty acid synthesis and subsequent triglyceride synthesis.

Metabolism is the set of chemical reactions that occur in living organisms in order to maintain life.  These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments.  Metabolism is usually divided into two categories.  Catabolism breaks down large molecules, for example to harvest energy in cellular respiration.  Anabolism, on the other hand, uses energy to construct components of cells such as proteins and nucleic acids.   The chemical reactions of metabolism are organized into metabolic pathways, in which one chemical is transformed into another by a sequence of enzymes.  Enzymes are crucial to metabolism because they allow organisms to drive desirable but thermodynamically unfavorable reactions by coupling them to favorable ones.  Enzymes also allow the regulation of metabolic pathways in response to changes in the cell's environment or signals from other cells.  The metabolism of an organism determines which substances it will find nutritious and which it will find poisonous.  For example, some prokaryotes use hydrogen sulfide as a nutrient, yet this gas is poisonous to animals. The speed of metabolism, the metabolic rate, also influences how much food an organism will require.  A striking feature of metabolism is the similarity of the basic metabolic pathways between even vastly different species.  For example, the set of carboxylic acids that are best known as the intermediates in the citric acid cycle are present in all organisms, being found in species as diverse as the unicellular bacteria Escherichia coli and huge multicellular organisms like elephants.  These striking similarities in metabolism are most likely the result of the high efficiency of these pathways, and of their early appearance in evolutionary history. 

Molecule is defined as a sufficiently stable electrically neutral group of at least two atoms in a definite arrangement held together by strong chemical bonds.  In organic chemistry and biochemistry, the term molecule is used less strictly and also is applied to charged organic molecules and biomolecules.

Pancreas is the organ in the body that produces the hormone insulin.  The pancreas is a gland organ in the digestive and endocrine systems of vertebrates.  It is both exocrine (secreting pancreatic juice containing digestive enzymes) and endocrine (producing several important hormones, including insulin, glucagon, and somatostatin).

Protein  Many foods contain protein but the best sources are beef, poultry, fish, eggs, dairy products, nuts, seeds, and legumes like black beans. Protein builds up, maintains, and replaces the tissues in your body. (Not the tissues you blow your nose in! We mean the stuff your body's made up of.) Your muscles, your organs, and your immune system are made up mostly of protein.  Your body uses the protein you eat to make lots of specialized protein molecules that have specific jobs.  For instance, your body uses protein to make hemoglobin, the part of red blood cells that carries oxygen to every part of your body. Other proteins are used to build cardiac muscle. What's that? Your heart! In fact, whether you're running or just hanging out, protein is doing important work like moving your legs, moving your lungs, and protecting you from disease.

Simple Carbohydrates are usually considered to be "bad" carbs, but these are those that have been processed and broken down before being put back together again in an unnatural way such as to produce a sweet product like chocolate.  Natural simple carbohydrates are the best carbs to include in the diet, especially if trying to lose weight.

Sugar (the word stems from the Sanskrit sharkara) consists of a class of edible crystalline substances including sucrose, lactose, and fructose.  Human taste-buds interpret its flavor as sweet.  Sugar as a basic food carbohydrate primarily comes from sugar cane and from sugar beet, but also appears in sorghum, as sugar maple (in maple syrup), and from many other sources. It forms the main ingredient in much candy.

Syndrome X is another term heard in the news.  Syndrome X is a cluster of risk factors for heart disease associated with insulin resistance.  These risk factors include: hypertriglyceridemia (high blood lipid), low HDL-cholesterol, hyperinsulinemia (high blood insulin), often hyperglycemia (high blood glucose), and hypertension (high blood pressure).

Triglyceride is glyceride in which the glycerol is esterified with three fatty acids.  It is the main constituent of vegetable oil and animal fats.  Triglycerides, as major components of very low density lipoprotein (VLDL) and chylomicrons, play an important role in metabolism as energy sources and transporters of dietary fat.  They contain more than twice as much energy (9 kcal/g) as carbohydrates and proteins.  Triglycerides are one of the components of a lipoprotein (in addition to cholesterol and other components).  Triglycerides are the main constituents of stored fat.

Mike Beatty
CEO ITG Diet