idiopathic. Term describing a disease of unknown cause.

immune globulin. A protein that functions as an antibody in the body's immune response. Immune globulins are manufactured by certain white blood cells and found in body fluids and on mucous membranes.

immune system. A complex system that depends on the interaction of many different organs, cells, and proteins. Its chief function is to identify and eliminate foreign substances such as harmful bacteria that have invaded the body. The liver, spleen, thymus, bone marrow, and lymphatic system all play vital roles in the proper functioning of the immune system.

immunity. The condition of being able to resist and overcome disease or infection.

immunodeficiency. A defect in the functioning of the immune system. It can be inherited or acquired, reversible or permanent. Immunodeficiency renders the body more susceptible to illness of every type, especially infectious illnesses. 

immunology. The branch of medical science that deals with the functioning of the immune system.

immunotherapy. Treatment of disease by using techniques to stimulate or strengthen the immune system.

incubation period. The period of time between exposure to an infectious disease and the appearance of symptoms, during which the infection is developing.

infection. Invasion of body tissues by disease-causing organisms such as viruses, protozoa, fungi, or bacteria. 

infestation. An invasion of the body by parasites such as insects, worms, or protozoa.

inflammation. A reaction to illness or injury characterized by swelling, warmth, and redness.

inguinal. Pertaining to the groin.

insomnia. The inability to sleep.

insulin. A hormone produced by the pancreas that regulates the metabolism of glucose (sugar) in the body.

interaction. A phenomenon that occurs when two or more substances affect one another's activity or combine to create a different effect than any of them would have on its own. Any substance introduced into the body can potentially interact with another substance or substances already present. Drugs, foods, herbs, minerals, and vitamins can all interact with one another.

interferon. A protein produced by the cells in response to viral infection that prevents viral reproduction and is capable of protecting uninfected cells from viral infection. There are different types of interferon, designated alpha, beta, and gamma.

intestinal flora. The "friendly" bacteria present in the intestines that are essential for the digestion and metabolism of certain nutrients.

intolerance. Nutritionally, the inability to digest a particular food, usually due to a lack or deficiency of certain enzymes.

intravenous (IV) infusion. The use of a needle inserted in a vein to assist in fluid replacement or the giving of medication.

ischemia. The condition of being starved for blood. Ischemia affecting the heart or brain can cause a heart attack or stroke. IU. International unit. A measure of potency based on an accepted international standard. Dosages of vitamin A and E supplements, among others, are usually measured in international units. Because this is a measurement of potency, not weight or volume, the number of milligrams in an international unit varies, depending on the substance being measured.

lactase. An enzyme that converts lactose into glucose and galactose. It is necessary for the digestion of milk and milk products.

lactic acid. An acid that results from anaerobic glucose metabolism. It is present in certain foods, including certain fruits and sour milk (when milk becomes sour, this means that some of the lactose, or milk sugar, it contained has been converted into lactic acid). Lactic acid is also produced in the muscles during anaerobic exercise. It is the buildup of lactic acid that causes muscle fatigue during strenuous activity. Synthetic lactic acid is used in food products as a flavoring and preservative.

lactobacilli. Any of a number of species of bacteria that are capable of transforming lactose (milk sugar) into lactic acid through fermentation. Lactobacilli are naturally present in the colon, and are sometimes referred to as "friendly" bacteria because they aid in digestion and fight certain diseasecausing microorganisms. The two species of lactobacilli most commonly available in supplement form are L. acidophilus and L. bifidus.

laser. Light amplification by stimulated emission of radiation. An instrument that focuses highly amplified light waves. Lasers are used in surgical procedures, especially eye surgery.

lecithin. A mixture of phospholipids that is composed of fatty acids, glycerol, phosphorus, and choline or inositol. All living cell membranes are largely composed of lecithin.

leukemia. Cancer of the blood-producing tissues, especially the bone marrow and lymph nodes, resulting in an overabundance of white blood cells. It can be either acute (most common in children) or chronic (most common in adults). It is similar in certain respects to Hodgkin's disease.

limbic system. A group of deep brain structures that, among other things, transmit the perception of pain to the brain and generate an emotional reaction to it.

lipid. Substances found in nature that are soluble in the same organic solvents as fats and oils are. Important nutritional lipids include choline, gamma-linolenic acid, inositol, lecithin, and linoleic acid.

lipoprotein. A type of protein molecule that incorporates a lipid. Lipoproteins act as agents of lipid transport in the lymph and blood.

lipotropic. Any of a number of substances that help to prevent the accumulation of abnormal or excessive amounts of fat in the liver, control blood sugar levels, and enhance fat and carbohydrate metabolism. Commonly used lipotropics include choline, inositol, and methionine.

lymph. A clear fluid derived from blood plasma that circulates throughout the body, is collected from the tissues, and flows through the lymphatic vessels, eventually returning to the blood circulation. Its function is to nourish tissue cells and return waste matter to the bloodstream.

lymph nodes. Organs located in the lymphatic vessels that act as filters, trapping and removing foreign material. They also form lymphocytes, immune cells that develop the capacity to seek out and destroy specific foreign agents.

lymphadenopathy. Enlargement of a lymph node or nodes as a result of the presence of a foreign substance or disease. This condition is often referred to as "swollen glands."

lymphocyte. A type of white blood cell found in lymph, blood, and other specialized tissues, such as the bone marrow and tonsils. There are several different categories of lymphocytes, designated B-lymphocytes, T-lymphocytes, and null (or non-B, non-T) lymphocytes. These cells are crucial components of the immune system. B-lymphocytes are primarily responsible for antibody production, whereas the T-lymphocytes are involved in the direct attack against invading organisms. It is the T-helper cell, a subtype of T-lymphocyte, that is the primary cell infected and destroyed by human immunodeficiency virus (HIV), the virus that causes AIDS.

lymphokine. Any of a group of substances produced by the cells of the immune system when exposed to antigens. They are not antibodies, but rather perform such functions as stimulating the production of additional lymphocytes and activating other immune cells.

lymphoma. Cancer of the lymphatic tissues.

macrobiotics. A dietary approach adapted from Far Eastern philosophy whose basic principle consists of balancing the yin and yang energies of foods. Yin foods, such as water, are expansive; yang foods, such as salt or meat, are contractile. For the most part, the macrobiotic diet consists of whole grain cereals, millet, rice, soups, and vegetables, with beans and supplementary foods depending on the individual and the condition. Different conditions are considered either yin or yang, so the macrobiotic program must be adapted to each individual.

malabsorption. Nutritionally, a defect in the absorption of nutrients from the intestinal tract into the bloodstream.

malignant. Literally, 'evil." Used to refer to cells or groups of cells that are cancerous and likely to spread. 

mammography. An x-ray examination of the breast.

melanoma. A malignant tumor originating from pigment cells in the deep layers of the skin.

menopause. The cessation of menstruation, caused by a sharp decrease in the production of the sex hormones estrogen and progesterone. Menopause usually occurs after the age of forty-five or following the removal of the female reproductive organs.

metabolism. The physical and chemical processes necessary to sustain life, including the production of cellular energy, the synthesis of important biological substances, and degradation of various compounds.

metabolite. A substance produced as a result of a metabolic process.

microgram. A measurement of weight equivalent to 1/1,ooo of a milligram.

milligram. A measurement of weight equivalent to 1/i,ooo of a gram (a gram is equal to approximately 1/28 of an ounce).

mineral. An inorganic substance required by the body in small quantities. 

MRI. Magnetic resonance imaging. A technique used in diagnosis that combines the use of radio waves and a strong magnetic field to produce detailed images of the internal structures of the body.

mucous membranes. Membranes that line the cavities and canals of the body that communicate with the air. Examples include the membranes lining the inside of the mouth, nose, anus, and vagina.

naturopathy. A form of health care that uses diet, herbs, and other natural methods and substances to cure illness. The goal is to produce a healthy body state without the use of drugs by stimulating innate defenses. 

neuropathy. A complex of symptoms caused by abnormalities in motor or sensory nerves. Symptoms may include tingling or numbness, especially in the hands or feet, followed by gradual, progressive muscular weakness.

neurotransmitter. A chemical that transmits nerve impulses from one nerve cell to another. Major neurotransmitters include acetylcholine, dopamine, gamma-aminobutyric acid, norepinephrine, and serotonin. 

nucleic acid. Any of a class of chemical compounds found in all viruses and plant and animal cells. Ribonucleic acid (RNA) and deoxyribonucleic acid (DNA), which contain the genetic instructions for every living cell, are two principal types.

nutraceutical. A food- or nutrient-based product or supplement designed and/or used for a specific clinical and/or therapeutic purpose.

nutrient. A substance that is needed by the body to maintain life and health.

occult blood test. A test that detects the presence of,blood in bodily excretions such as stool, sputum, or urine. It is most often used in screening for cancer. oncologist. A cancer specialist.

oncology. The medical specialty dealing with cancer.

organic. A term used to describe foods that are grown without the use of synthetic chemicals, such as pesticides, herbicides, and hormones.

osteopathy. A system of medicine based on the belief that the body is a vital mechanical organism whose structural and functional integrity are coordinated and interdependent, and that disturbances in the musculoskeletal system can therefore cause disorders elsewhere in the body. Because of this philosophy, although osteopaths can prescribe drugs and perform surgery, they are more likely to recommend physical therapy or musculoskeletal manipulation as the treatment of first choice.

osteoporosis. A disorder in which minerals leach out of the bones, rendering them progressively more porous and fragile.

oxidation. A chemical reaction in which oxygen reacts with another substance, resulting in a chemical transformation. Many oxidation reactions result in some type of deterioration or spoilage.

Pap test. Microscopic examination of cells collected from the vagina and cervix to test for signs of cancer. parasite. An organism that lives on or in another organism and obtains nourishment from it.

pH. Potential of hydrogen. A scale used to measure the relative acidity or alkalinity of substances. The scale runs from 0 to 14. A pH of 7 is considered neutral; numbers below 7 denote increasing acidity and numbers above 7 denote increasing alkalinity.

pharyngitis. Sore throat.

phenylketonuria (PKU). An inherited disorder caused by a lack of an enzyme necessary to convert the amino acid phenylalanine into another amino acid, tyrosine, so that excesses can be eliminated from the body. A buildup of excess phenylalanine in the blood can lead to neurological disturbances and mental retardation. 

phytochemical. Any one of many substances present in fruits and vegetables that have various health-promoting properties. Some phytochemicals appear to protect against certain types of cancer.

pituitary. A gland located at the base of the brain that secretes a number of different hormones. Pituitary hormones regulate growth and metabolism by coordinating the actions of other endocrine glands.

placebo. A pharmacologically inactive substance, primarily used in experiments to provide a basis for comparison with pharmacologically active substances.

plaque. An unwanted deposit of a certain substance on tissues, often with the potential to cause some type of health problem. The buildup of plaque in the arteries is a leading cause of cardiovascular disease; plaque deposits on the teeth can lead to gum disease; Alzheimer's disease is associated with the accumulation of characteristic plaques in brain tissue.

precancerous lesion. Abnormal tissue that is not malignant, but that may be in the process of becoming so. 

prognosis. A forecast as to the likely course and/or outcome of a disorder or condition.

prostaglandin. Any of a number of hormonelike chemicals that 78 have important effects on target organs. They influence the secretion of hormones and enzymes, and are important in regulating the inflammatory response, blood pressure, and blood clotting time.

protein. Any of many complex nitrogen-based organic compounds made up of different combinations of amino acids. Proteins are basic elements of all animal and vegetable tissues. Biological substances such as hormones and enzymes also are composed of protein. The body makes the specific proteins it needs for growth, repair, and other functions from amino acids that are either extracted from dietary protein or manufactured from other amino acids.

proteolytic enzymes. Enzymes that break down dietary proteins, yet do not attack the proteins that make up the normal cells of the body. Proteolytic enzymes may have value in fighting cancer and other diseases. Cancer cells have a type of protein coating; theoretically, if this coating is destroyed by proteolytic enzymes, the white blood cells would be able to attack the cancer cells and destroy them.

pruritus. Itching.

pulmonary. Pertaining to the lungs.

purulent. Containing or causing the production of pus.

radiation. Energy that is emitted or transmitted in the form of waves. The term is often used to refer to radioactivity; however, radioactivity is a specific type of radiation that comes from the decay of unstable atoms.

radiation therapy. A type of treatment, most often used for cancer, that involves the use of ionizing radiation, including Roentgen rays, radium, or other radioactive substances to destroy specific areas of tissue. Also called radiotherapy.

RAST. Radioallergosorbent test. A blood test that measures levels of specific antibodies produced by the body's immune system, used to test for allergic reactions.

RDA. Recommended daily allowance. The amount of a vitamin or other nutrient that should be consumed daily in order to prevent nutritional deficiency. RDAs are determined by the U.S. Food and Drug Administration.

red blood cell. A blood cell that contains the red pigment hemoglobin and transports oxygen and carbon dioxide in the bloodstream.

remission. Lessening or reversal of the signs and symptoms of disease. This term is used particularly of serious and/or chronic illnesses such as cancer and multiple sclerosis.

renal. Pertaining to the kidneys.

retinoic acid. Vitamin A acid. A form of retinoic acid is the active ingredient in the medication Retin-A.

retrovirus. A type of virus that has RNA as its core nucleic acid and contains an enzyme called reverse transcriptase that permits the virus to copy its RNA into the DNA of infected cells, in effect taking over the cells' genetic machinery. Human immunodeficiency virus (HIV), the virus that causes AIDS, is a retrovirus. Retroviruses are also known tocause certain types of cancer inanimals, and are suspected of causing forms of leukemia and lymphoma in humans.

RNA. Ribonucleic acid. A complex protein found in plant and animal cells. RNA carries coded genetic information from DNA, in the cell nucleus, to protein-producing cell structure made in the body from essential fatty acids and that tures called ribosomes, where these instructions are translated into the form of protein molecules-the basic component of all living tissue.

saturated fat. A fat that is solid at room temperature. Most saturated fats are of animal origin, although a few, such as coconut oil and palm oil, come from plants.

saturation. With regard to fats, the term saturation" refers to the chemical structure of the fatty acid molecules, specifically the number of hydrogen atoms present. Fat molecules that cannot incorporate any additional hydrogen atoms are said to be saturated; those that could incorporate one additional hydrogen atom are referred to as monounsaturated; and those that could incorporate two or more additional hydrogen atoms are referred to as polyunsaturated.

scratch test. A procedure in which a small amount of a suspected allergen is applied to a lightly scratched area of skin to test for an allergic reaction.

sebum. The oily secretion produced by glands in the skin.

secondary infection. An infection that develops after and is made possible by the presence or effect of a previous infection, inflammation, or other condition, but that is not necessarily directly caused by it,

seizure. A sudden, brief episode characterized by changes in consciousness, perception, muscular motion, and/or behavior. A convulsion is a type of seizure.

serotonin. A neurotransmitter found principally in the brain that is considered essential for relaxation, sleep, and concentration.

serum. The fluid portion of the blood.

simple carbohydrate. A type of carbohydrate that, owing to its chemical structure, is rapidly digested and absorbed into the bloodstream. Glucose, lactose, and fructose are examples of simple carbohydrates.

sorbic acid. An organic acid used as a food preservative.

steroid. One of a group of fat-soluble organic compounds with a characteristic chemical composition. A number of different hormones, drugs, and other substances-including cholesterol-are classified as steroids. 

stroke. An attack in which the brain is suddenly deprived of oxygen as a result of interrupted blood flow. If it continues for more than a few minutes, brain damage and even death may result.

sublingual. Literally, "under the tongue." Sublingual medications and supplements often look like tablets or liquids meant for swallowing, but they are designed to be held in the mouth while the active ingredient is absorbed into the bloodstream through the mucous membranes.

symptom. An alteration in normal feeling or functioning experienced as a result of a bodily disorder. 

syncope. Temporary loss of consciousness; fainting.

syndrome. A group of signs and symptoms that together are known or presumed to characterize a disorder. 

synergy. An interaction between two or more substances in which their action is greater when they are together than the sum of their individual actions would be.

systemic. Pertaining to the entire body.

T cell. A type of lymphocyte that is a crucial part of the immune system.

teratogen. An agent that causes malformation of a developing embryo or fetus. ther

therapy, alternative. The treatment of disease by means o than conventional medical, pharmacological, and surgical techniques.

thrombus. An obstruction in a blood vessel.

thrush. A fungal infection caused by Candida albicans that is characterized by small whitish spots on the tongue and the insides of the cheeks. It occurs most often in infants and in persons with compromised immune systems.

topical. Pertaining to the surface of the body.

toxicity. The quality of being poisonous. Toxicity reactions in the body impair bodily functions and/or damage cells.

toxin. A poison that impairs the health and functioning of the body.

trace element. A mineral required by the body in extremely small quantities.

tremor. Involuntary trembling.

triglyceride. A compound consisting of three fatty acids plus glycerol. Triglycerides are the form in which fat is stored in the body, and are the primary type of lipid in the diet.

tumor. An abnormal mass of tissue that serves no function.

Tumors are usually categorized as either benign or malignant (cancerous).

type A personality. A personality that tends to be impatient and aggressive. Persons with type A personalities tend to have stronger stress reactions, and may be more susceptible to cardiovascular disease.

type B personality. A personality that tends to be relaxed and patient, and less reactive to stress. Those with type B personalities may be less prone to develop stress-related illnesses such as high blood pressure and heart disease.

ultrasound. Ultra-high-frequency sound waves. Ultrasound technology is used in a number of different medical diagnostic and treatment tools.

unsaturated fat. Any of a number of dietary fats that are liquid at room temperature. Unsaturated fats come from vegetable sources and are good sources of essential fatty acids. Examples include flaxseed oil, sunflower oil, safflower oil, and primrose oil.

urticaria. Hives.

vaccine. A preparation administered to achieve immunity against a specific agent by inducing the body to make antibodies to that agent. A vaccine maybe a suspension of living or dead microorganisms, or a solution of an allergen or viral or bacterial antigens.

vascular. Pertaining to the circulatory system.

vein. One of the blood vessels that returns the blood from the body tissues to the heart.

venom. A poisonous substance produced by an animal, such as certain snakes and insects.

virus. Any of a vast group of minute, often disease-causing, structures composed of a protein coat and a core of DNA and/or RNA. Because they are incapable of reproducing on their own (they must reproduce inside the cells of an infected host), viruses are not technically considered living organisms. Unlike bacteria, viruses are not affected by antibiotics.

visualization. A technique that involves consciously using the mind to influence the health and functioning of the body. Also called creative visualization.

vital signs. Basic indicators of an individual's health status, including pulse, breathing, blood pressure, and body temperature.

vitamin. One of approximately fifteen organic substances that are essential in small quantities for life and health. Most vitamins cannot be manufactured by the body, and so need to be supplied in the diet.

water-soluble. Capable of dissolving in water.

white blood cell. A blood cell that functions in fighting infection and in wound repair.

withdrawal. The process of adjustment that occurs when the use of a habit-forming substance to which the body has become accustomed is discontinued.

yeast. A type of single-celled fungus. Certain types of yeast can cause infection, most commonly in the mouth, vagina, or gastrointestinal tract. Common yeast infections include vaginitis and thrush.

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