specialized connective tissue that functions to store body fat as triglycerides.
a treatment or therapy used in addition to another, not alone.
a pair of small glands, located above the kidneys, consisting of an outer cortex and inner medulla. The adrenal cortex secretes cortisone-related hormones and the adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline).
the nonsugar component of a glycoside. Cleavage of the glycosidic bond of a glycoside results in the formation of a sugar and an aglycone.
adequate intake. Established by the Food and Nutrition Board of the US Institute of Medicine, the AI is a recommended intake value based on observed or experimentally determined estimates of nutrient intake by a group of healthy people that are assumed to be adequate. An AI is established when an RDA cannot be determined.
acquired immune deficiency syndrome. AIDS is caused by the HIV (Human Immunodeficiency Virus) virus, which attacks the immune system, leaving the infected individual vulnerable to opportunistic infections.
a plant-derived compound that is biologically active, contains a nitrogen in a heterocyclic ring, is alkaline, has a complex structure, and is of limited distribution in the plant kingdom.
one of a set of alternative forms of a gene. Diploid cells possess two homologouschromosomes (one derived from each parent) and therefore two copies of each gene. In a diploid cell, a gene will have two alleles, each occupying the same position on homologous chromosomes.
loss of hair.
the most common cause of dementia in older adults. Alzheimer’s disease is characterized by the formation of amyloid plaque in the brain and nerve cell degeneration. Symptoms include memory loss and confusion, which worsen over time.
an organic molecule that contains an amino group (-NH2) and a carboxyl group (-COOH); amino acids are as the building blocks of proteins.
adenosine monophosphate. A important compound in energy metabolism. Addition of two phosphates to AMP forms ATP.
a chemical compound having both hydrophilic (water-loving, polar) and lipophilic (fat-loving, nonpolar) properties.
aggregates of a peptide called amyloid-β, which accumulate and form deposits in the brain in Alzheimer’s disease.
Amyotrophic lateral sclerosis (ALS)
a rapidly progressive and fatal neurological disease caused by degeneration of motor neurons that control voluntary muscle movement. Also known as Lou Gehrig’s disease.
the synthesis of large complex molecules from simple molecules.
refers to the absence of oxygen or the absence of a need for oxygen.
a chemical compound that is structurally similar to another but differs slightly in composition (e.g., the replacement of one functional group by another).
a rapidly developing and severe systemic allergic reaction. Symptoms may include swelling of the tongue, throat, and trachea, which can result in difficulty breathing, shock and loss of consciousness. If not treated rapidly, anaphylaxis can be fatal.
the condition of having less than the normal number of red blood cells or hemoglobin in the blood, resulting in diminished oxygen transport. Anemia has many cause, including iron, vitamin B12, or folate deficiency; bleeding; abnormal hemoglobin formation (e.g., sickle cell anemia); rupture of red blood cells (hemolytic anemia); and bone marrow diseases.
a birth defect, known as a neural tube defect, resulting from failure of the upper end of the neural tube to close during embryonic development. Anencephaly is a devastating and sometimes fatal birth defect resulting in the absence of most or all of the cerebral hemispheres.
pain generally experienced in the chest, but sometimes radiating to the arms or jaw, due to a lack of oxygen supply to the heart muscle.
the development of new blood vessels.
imaging of the coronary arteries used to identify the location and severity of any obstructions. Coronary angiography typically involves the administration of a contrast medium and imaging of the coronary arteries using an X-ray based technique.
a substance that is capable of eliciting an immune response.
a chemical that blocks the effect of histamine in a susceptible tissues. Histamine is released by immune cells during an allergic reaction and also during infection with viruses that cause the common cold. The interaction of histamine with the mucus membranes of the eyes and nose results in "watery eyes" and the "runny nose" often accompanying allergies and colds. Antihistamines can help alleviate such symptoms.
capable of killing or inhibiting the growth of microorganisms, such as bacteria.
a scoring system used to assess the physical condition of a newborn immediately after birth. Criteria evaluated include respiratory effort, heart rate, skin coloration, muscle tone, and response to stimulation.
gene-directed cell death or programmed cell death that occurs when age, condition, or state of cell health dictates. Cells that die by apoptosis do not usually elicit the inflammatory responses that are associated with necrosis. Cancer cells are resistant to apoptosis.
referring to water or a solution containing water.
an abnormal heart rhythm. The heart rhythm may be too fast (tachycardia), too slow (bradycardia) or irregular. Some arrhythmias, such as ventricular fibrillation, may lead to cardiac arrest if not treated promptly.
a lack of oxygen or excess carbon dioxide in the body that causes unconsciousness.
a chronic inflammatory disease of the airways, characterized by recurrent episodes of reversible airflow obstruction.
adenosine triphosphate. An important compound for the storage of energy in cells, as well as the synthesis of nucleic acids.
(singular: atrium) two upper chambers of the heart that receive blood from the veins and contract to force that blood into the ventricles.
a cardiac arrhythmia, characterized by rapid, uncoordinated beating of the atria, which results in ineffective atrial contractions. Atrial fibrillation is known as a supraventricular arrhythmia because it originates above the ventricles.
a chronic inflammation of the lining of the stomach, which ultimately results in the loss of glands in the stomach (atrophy) and decreased stomach acid production.
a decrease in size or wasting away of a body part or tissue.
a reduction in number.
a condition in which the body's immune system reacts against its own tissues.
the phosphorylation by a protein of one or more of its own amino acid residues. Autophosphorylation does not necessarily occur on the same polypeptide chain as the catalytic site. In a dimer, one subunit may phosphorylate the other.
refers to a trait or gene that is not located on the X or Y chromosome (not sex-linked).
long extension of a neuron that transmits nerve impulses away from the cell body toward other neurons or muscle cells.
single-celled organisms that can exist independently, symbiotically (in cooperation with another organism) or parasitically (dependent upon another organism, sometimes to the detriment of the other organism). Examples of bacteria include acidophilus (found in yogurt); streptococcus the cause of strep throat; and E. coli (a normal intestinal bacteria, as well as a disease-causing agent).
a nutritional balance study involves the measurement of the intake of a specific nutrient as well as the elimination of that nutrient in urine, feces, sweat, etc. If intake is greater than loss of a particular nutrient the individual is said to be in "positive balance." If intake is less than loss, an individual is said to be in "negative balance" for the nutrient of interest.
the branch of medicine that relates to the treatment of obesity.
the term used to describe a noncancerous enlargement of the prostate.
any systematic error in an epidemiological study that results in an incorrect estimate of the association between an exposure and disease risk.
a yellow, green fluid made in the liver and stored in the gallbladder. Bile may then pass through the common bile duct into the small intestine where some of its components aid in the digestion of fat.
the fraction of an administered compound that reaches the systemic circulation and is transported to site of action (target tissue).
a physical, functional, or biochemical indicator of a physiological or disease process.
Biotransformation enzymes (phase I and phase II)
enzymes involved in the metabolism and elimination of a variety of exogenous (drugs, toxins and carcinogens) and endogenous compounds (steroidhormones). In general, phase I biotransformation enzymes, including those of the cytochrome P450 family, catalyze reactions that increase the reactivity of fat-soluble compounds and prepare them for reactions catalyzed by phase II biotransformation enzymes. Reactions catalyzed by phase II enzymes generally increase water solubility and promote the elimination of these compounds.
a mood disorder previously called “manic-depressive illness.” Bipolar disorder is characterized by severe alterations in mood. During “manic” episodes, a person may experience extreme elevation in energy level and mood (euphoria) or extreme agitation and irritability. Episodes of depressed mood are also common in bipolar disorder.
Body mass index (BMI)
body weight in kilograms divided by height in meters squared. In adults, BMI is a measure of body fat: underweight, <18.5; normal weight, 18.5-24.9; overweight, 25-29.9; obese, ≥30. Calculate your BMI.
Bone mineral density (BMD)
the amount of mineral in a given area of bone. BMD is positively associated with bone strength and resistance to fracture, and measurements of BMD are used to diagnose osteoporosis.
the continuous turnover process of bone that includes bone resorption and bone formation. An imbalance in the regulation of the two contrasting events of bone remodeling (bone resorption and bone formation) increases the fragility of bone and may lead to osteoporosis.
a rumbling sound caused by gas movement in the intestines; sometimes called "stomach rumble."
Branched-chain amino acids
the essential amino acids: leucine, isoleucine, and valine.
long-standing inflammation of the airways, characterized by excess production of sputum, leading to a chronic cough and obstruction of air flow. Cigarette smoking is the most common cause of chronic bronchitis.
a chemical used to maintain the pH of a system by absorbing hydrogen ions (which would make it more acidic) or absorbing hydroxyl ions (which would make it more alkaline).
the process of deposition of calcium salts. In the formation of bone this is a normal condition. In other organs, this could be an abnormal condition; for example, calcification of the aortic valve causes narrowing of the passage (aortic stenosis).
refers to abnormal cells, which have a tendency to grow uncontrollably and metastasize or spread to other areas of the body. Cancer can involve any tissue of the body and can have different forms in one tissue. Cancer is a group of more than 100 different diseases.
considered a macronutrient because carbohydrates provide a significant source of calories (energy) in the diet. Chemically, carbohydrates are neutral compounds composed of carbon, hydrogen and oxygen. Carbohydrates come in simple forms known as sugars and complex forms, such as starches and fiber.
the pattern of symptoms exhibited by individuals with carcinoid tumors. Carcinoid tumors secrete excessive amounts of the neurotransmitter, serotonin. Symptoms may include flushing, diarrhea, and sometimes wheezing.
volume of blood pumped by the heart in a specified time period.
literally, disease of the heart muscle that often leads to abnormal function.
a compound that is required to transport long-chain fatty acids across the inner membrane of the mitochondria, in the form of acyl-carnitine, where they can be metabolized for energy.
the left and right common carotid arteries are the principal blood vessels that supply oxygenated blood to the head and neck. Each has two main branches, the external and internal carotid artery.
a soft, elastic tissue that composes most of the skeleton of vertebrate embryos and except for a small number of structures is replaced by bone during ossification in the higher vertebrates. Cartilage cushions joints, connects muscles with bones, and makes up other parts of the body, such as the larynx (voice box) and the outside portion of the ears.
a study in which exposures of people who have been diagnosed with a disease (cases) are compared to those of people without the disease (controls). The results of case-control studies are more likely to be distorted by bias in the selection of cases and controls (selection bias) and dietary recall (recall bias) than prospective cohort studies.
a report that decribes an individual case of a disease or medical condition. This type of research cannot indicate causality but may indicate areas for further research.
the breakdown of complex molecules into smaller ones, accompanied by the release of energy.
to increase the speed of a chemical reaction without being changed in the overall reaction process. See enzyme.
clouding of the lens of the eye. As cataracts progress, they can impair vision.
a substance with a specific chemical structure (a benzene ring with two adjacent hydroxyl groups and a side chain of ethylamine) that functions as a hormone or neurotransmitter. Examples include epinephrine, norepinephrine, and dopamine.
also known as celiac sprue, celiac disease is an inherited disease in which the intestinal lining is inflamed in response to the ingestion of a protein known as gluten. Treatment of celiac disease involves the avoidance of gluten, which is present in many grains, including wheat, rye, oats, and barley. Inflammation and atrophy of the lining of the small intestine leads to impaired nutrient absorption.
Cell adhesion molecule
a molecule on the outside surface of cells that binds to other cells or to the extracellular matrix (material surrounding cells). Cell adhesion molecules influence many important functions, including the entry of immune cells into the arterial wall.
the orderly sequence of stages that a cell passes through between one cell division (mitosis) and the next. The cell cycle can be divided into four stages: the M (mitosis) phase, in which nuclear and cytoplasmic division occurs; the G1 phase or interphase; the S (synthesis) phase, in which DNA replication occurs; and the G2 phase, a quiescent period prior to the next M phase.
also called a plasma membrane; the barrier that separates the contents of a cell from its outside environment and controls what moves in and out of the cell. A mammalian cell membrane consists of a phospholipid bilayer with embedded proteins and cholesterol.
communication among individual cells so as to coordinate their behavior to benefit the organism as a whole. Cell-signaling systems elucidated in animal cells include cell-surface and intracellular receptorproteins, GTP-binding proteins, as well as protein kinases and protein phosphatases (enzymes that phosphorylate and dephosphorylate proteins).
Central nervous system (CNS)
the brain, spinal cord, and spinal nerves.
a specialized type of lipid comprised of a sphingosine backbone with fatty acid side chains. Ceramides function as signaling molecules and are critical structural components in cell membranes.
relating to the brain.
the fluid that bathes the brain and spinal cord.
disease involving the blood vessels supplying the brain, including cerebrovascular accident (CVA), also known as a stroke.
the upper part of the brain that is involved in conscious mental functions.
a ferroxidase enzyme that has the capacity to oxidize ferrous iron (Fe2+) to ferric iron (Fe3+), which can be loaded onto the iron-transport protein, transferrin.
Cervical intraepithelial neoplasia (CIN)
a term used to describe abnormal growth of cells on the surface of the uterine cervix. CIN1 is also known as low-grade squamous intraepithelial lesion (LSIL). CIN2 and CIN3 are also known as high-grade squamous intraepithelial lesions (HSIL). Although these abnormal cells are not cancerous, they may progress to cervical cancer.
the combination of a metal with an organic molecule to form a ring-like structure known as a chelate. Chelation of a metal may inhibit or enhance its bioavailability.
movement of a cell or organism toward or away from a chemical stimulus.
literally, treatment with drugs. Commonly used to describe the systemic use of drugs to kill cancer cells, as a form of cancer treatment.
resembling acetylcholine in action, a cholinergic drug for example. Cholinergic nerve fibers liberate or are activated by the neurotransmitter, acetylcholine.
Chorionic villus sampling (CVS)
a procedure for obtaining a small sample of tissue from the placenta (chorionic villi) for the purpose of prenatal diagnosis of genetic disorders. CVS can be performed between 9 to 12 weeks of pregnancy.
a structure in the nucleus of a cell that contains genes. Chromosomes are composed of DNA and associated proteins. Normal human cells contain 46 chromosomes (22 pairs of autosomes and 2 sex chromosomes).
an illness lasting a long time. By definition of the US Center for Health Statistics, a chronic disease is a disease lasting three months or more.
triglyceride-rich lipoproteins that deliver dietary triglycerides from the intestine to the tissues immediately after a meal. Chylomicrons release their triglycerides to tissue through the activity of lipoprotein lipase enzymes in tissue capillary beds. When they are depleted of most of their triglycerides, chylomicron remnants are taken up by the liver, where the lipids and cholesterol that remain are excreted in bile or incorporated into other lipoproteins.
the mass of partially digested food that exits the stomach and enters the duodenum of the small intestine.
a condition characterized by irreversible scarring of the liver, leading to abnormal liver function. Cirrhosis has a number of different causes, including chronic alcohol use and viral hepatitis B and C.
Citric acid cycle
the metabolic pathway in the mitochondria that oxidizes acetyl compounds form food to carbon dioxide and water. Also referred to as the Krebs cycle and the tricarboxylic acid (TCA) cycle.
an intervention trial generally used to evaluate the efficacy and/or safety of a treatment or intervention in human participants.
an exact copy of a DNA segment; produced by recombinant DNA technology.
the process involved in blood clot formation.
a molecule that binds to an enzyme and is essential for its activity but is not permanently altered by the reaction. Many coenzymes are derived from vitamins.
a compound that is essential for the activity of an enzyme.
mental process of thought; includes brain functions like attention, memory, planning, developing strategies, and problem solving.
a study that follows a large group of people over a long period of time, often 10 years or more. In cohort studies, dietary information is gathered before disease occurs, rather than relying on recall after disease develops.
a fibrous protein that is the basis for the structure of skin, tendon, bone, cartilage and all other connective tissue.
Collagenous matrix (of bone)
the organic (nonmineral) structural element of bone. Collagen is a fibrous protein that provides the organic matrix upon which bone mineralize crystallizes.
the portion of the large intestine that extends from the end of the small intestine to the rectum. The colon removes water from digested food after it has passed through the small intestine and stores the remaining stool until it can be evacuated.
system of serumproteins that function to help destroy invading microorganisms.
accompanying. "Concomitant intake" refers to the intake of two compounds at the same time.
Conditionally essential nutrient
although not strictly considered a nutrient due to endogenoussynthesis, certain conditions (e.g., stress, aging) may result in the demand exceeding the body's capacity for synthesis, rendering a conditionally essential nutrient.
Confidence interval (CI)
a statistical measure of certainty. A CI defines the range within which we can be certain that a result is not due to chance alone.
an extraneous factor in an observational study that distorts or biases an association between an exposure and the measured outcome. Confounders are associated with the exposure and outcome of interest, but they are not in the causal pathway.
a birth defect, a condition present at birth.
deficiency of thyroid gland activity in newborn infants.
Congestive heart failure (CHF)
a condition, in which the heart loses the ability to pump blood efficiently enough to meet the demands of the body. Symptoms may include edema (swelling), shortness of breath, weakness and exercise intolerance.
a compound formed through joining (conjugation) of at least two chemical compounds.
the formation of a water-soluble derivative of a chemical by its combination with another compound, such as glutathione, glucuronate, or sulfate.
the transparent covering of the front of the eye that transmits and focuses light into the eye.
a metabolically inactive, flattened cell of the stratum corneum. Corneocytes are formed from keratinocytes in a process termed cornification. Corneocytes are metabolically inactive and will eventually be cast off from the body when new corneocytes are generated underneath them.
the process by which a keratinocyte becomes a corneocyte in the outer, visible layer of the epidermis. This is marked by a loss of intracellular organelles, the production of specialized proteins and lipids, and the generation of a thick protein envelope just inside the cell membrane. Corneocytes are metabolically inactive and will eventually be cast off from the body when new corneocytes are generated underneath them.
a procedure used to open an occluded coronary artery. A flexible hollow catheter is inserted into a large blood vessel in the groin and advanced to the heart. At the site of the occlusion, the balloon tip of the catheter is inflated and the occluded coronary artery is dilated. Coronary angioplasty is also known as percutaneous transluminal coronary angioplasty or PTCA.
one of the vessels that supply oxygenated blood to the heart muscle itself. They are called coronary arteries because they encircle the heart in the form of a crown.
Coronary artery bypass graft (CABG)
a surgical procedure used to create new routes around obstructions in coronary arteries and restore adequate blood flow to the heart muscle.
Coronary heart disease (CHD)
sometimes called coronary artery disease or coronary disease, coronary heart disease is the result of atherosclerosis of the coronary arteries. Atherosclerosis may result in narrowing or blockage of the coronary arteries and is the underlying cause of myocardial infarction (heart attack).
also known as compact bone, the type of bone that forms the outer surface of all bones. The small bones of the wrists, hands, and feet are entirely cortical bone.
any of the steroidhormones made by the cortex (outer layer) of the adrenal gland. Cortisol is a corticosteroid. A number of medications are analogs of natural corticosteroid hormones.
a chemical bond in which electrons are shared between atoms.
abnormal skull shape due to the fibrous sutures of the skull having turned into bone prematurely.
a high-energy compound found in muscle cells, which is used to convert ADP into ATP by donating phosphate molecules to the ADP. ATP is the molecule that is converted into ADP with a release of energy that the body then uses.
a condition that can result from a severe form of congenital hypothyroidism. Cretinism occurs in two forms, although there is considerable overlap. The neurologic form is characterized by mental and physical retardation and deafness. It is the result of maternal iodine deficiency that affects the fetus before its own thyroid is functional. The myxedematous or hypothyroid form is characterized by short stature and mental retardation. In addition to iodine deficiency, the hypothyroid form has been associated with selenium deficiency and the presence of goitrogens in the diet that interfere with thyroid hormone production.
a clinical trial where at least two interventions or treatments are applied to the same individuals after an appropriate wash-out period. One of the treatments is often a placebo. In a randomized cross-over design, interventions are applied in a randomized order to ensure that the order of treatments did not contribute to the outcome.
a study of a group of people at one point in time to determine whether an exposure is associated with the occurrence of a disease. Because the disease outcome and the exposure (e.g., nutrient intake) are measured at the same time, a cross-sectional study provides a “snapshot” view of their relationship. Cross-sectional studies cannot provide information about causality.
related to or affecting the skin.
Cystic fibrosis (CF)
a hereditary disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTCR) gene. Cystic fibrosis is characterized by the production of abnormal secretions, leading to the accumulation of mucus in the lungs, pancreas, and intestine. This build-up of mucus causes difficulty breathing and recurrent lung infections, as well as problems with nutrient absorption due to problems in the pancreas and intestines.
the formation of an essential molecule from simple precursor molecules.
the removal of necrotic or infected tissue or foreign material from a wound.
a chemical reaction involving the removal of a carboxyl (-COOH) group from a compound.
significant impairment of intellectual abilities, such as attention, orientation, memory, judgment or language. By definition, dementia is not due to major depression or psychosis. Alzheimer’s disease is the most common cause of dementia in older adults.
loss of the myelin sheath that surrounds a nerve fiber.
a branched extension of a neuron that receives signals from other neurons.
an immune cell that functions in antigen presentation and activation of T lymphocytes. Dendritic cells have a branched morphology that resembles dendrites of a neuron.
cavities or holes in the outer two layers of a tooth—the enamel and the dentin. Dental caries are caused by bacteria, which metabolizecarbohydrates (sugars) to form organic acids that dissolve tooth enamel.
a nutritional study designed to determine the requirement for a specific nutrient. Generally, subjects are placed on a diet designed to deplete them of a specific nutrient over time. Once depletion is achieved, gradually increasing amounts of the nutrient under study are added to the diet until the individual shows evidence of sufficiency or repletion.
inflammation of the skin. This term is often used to describe a skin rash.
any skin disease, especially one not characterized by inflammation.
the layers of skin below the epidermis that support the epidermis in both structure and function. Although the majority of cells in this layer are fibroblasts supported by a collagen network, blood vessels, immune cells, and adipose tissue are also found in the dermis.
DEXA or DXA
dual-energy X-ray absorptiometry. A precise instrument that uses the energy from very small doses of X-rays to determine bone mineral density (BMD) and to diagnose and follow the treatment of osteoporosis.
a chronic metabolic disease, characterized by abnormally high blood glucose (sugar) levels, resulting from the inability of the body to produce or respond to insulin. Type 1 diabetes mellitus, formerly known as insulin-dependent or juvenile-onset diabetes, is usually the result of autoimmune destruction of the insulin secreting β-cells of the pancreas. The most common form of diabetes is type 2 diabetes mellitus, formerly known as noninsulin-dependent or adult onset diabetes, which develops when the tissues of the body become less sensitive to insulin secreted by the pancreas.
a potentially life-threatening condition characterized by ketosis (elevated levels of ketone bodies in the blood) and acidosis (increased acidity of the blood). Ketoacidosis occurs when diabetes is not adequately controlled.
a medical procedure to filter waste products from the blood. Dialysis is needed to perform the work of the kidneys if they can no longer function effectively. Two types of dialysis are hemodialysis and peritoneal dialysis.
Diastolic blood pressure
the lowest arterial blood pressure during the heart beat cycle, and the second number in a blood pressure reading (e.g., 120/80).
changes in a cell resulting in its specialization for specific functions, such as those of a nerve cell. In general, differentiation of cells leads to a decrease in proliferation.
a passive process, in which particles in solution move from a region of higher concentration to one of lower concentration.
a complex of two molecules, usually proteins. Heterodimers are complexes of two different molecules, while homodimers are complexes of two of the same molecule.
an agent that increases the formation of urine by the kidneys, resulting in water loss from the individual using the diuretic.
a condition characterized by the formation of small pouches (diverticula) in the colon. Although most people with diverticulosis experience no symptoms, about 15-20% may develop pain or inflammation, known as diverticulitis.
deoxyribonucleic acid; a double-stranded nucleic acid composed of many nucleotides. The nucleotides in DNA are each composed of a nitrogen-containing base (adenine, guanine, cytosine, or thymine), a five-carbon sugar (deoxyribose), and a phosphate group. The sequence of bases in DNA encodes the genetic information required to synthesizeproteins.
a trait that is expressed when only one copy of the gene responsible for the trait is present.
refers to a study in which neither the investigators administering the treatment nor the participants know which participants are receiving the experimental treatment and which are receiving the placebo.
dietary reference intake. Refers to a set of at least four nutrient-based reference values (RDA, AI, UL, EAR), each with a specific use in defining recommended dietary intake levels for individual nutrients in the US. The DRIs are determined by expert panels appointed by the Food and Nutrition Board of the Institute of Medicine.
daily value. Refers to the dietary reference values required as the basis for declaring nutrient content on all products regulated by the US Food and Drug Administration (FDA), including nutritional supplements. The DVs for vitamins and minerals reflect the most up-to-date Dietary Reference Intakes.
estimated average requirement; a nutrient intake value that is estimated to meet the requirement of half of the healthy individuals in a particular life stage and gender group.
a diagnostic test that uses ultrasound to make images of the heart. It can be used to assess the health of the valves and chambers of the heart, as well as to measure cardiac output.
seizures in a woman caused by pregnancy-induced hypertension; a significant cause of maternal mortality.
an epidemiological study that examines the relationships between exposures and disease rates in a series of populations (e.g., different countries). Ecologic studies often rely on published statistics, such as food disappearance data or disease-specific death rates.
swelling; accumulation of excessive fluid in subcutaneous tissues (beneath the skin).
a chemical messenger derived from a 20-carbon polyunsaturated fatty acid, such as arachidonic acid and eicosapentaenoic acid. Eicosanoids play critical roles in immune and inflammatory responses.
a flexible structural protein similar to collagen; elastin is found in the dermal layer of skin and other parts of the body.
ionized (dissociated into positive and negative ions) salts in the body fluids. Major electrolytes in the body include sodium, potassium, magnesium, calcium, chloride, bicarbonate, and phosphate.
a stable atomic particle with a negative charge.
Electron transport chain
a group of electron carriers in mitochondria that transport electrons to and from each other in a sequence, in order to generate ATP.
one of the 103 chemical substances that cannot be divided into simpler substances by chemical means. For example, hydrogen, magnesium, lead, and uranium are all chemical elements. Trace elements are chemical elements that are required in very small (trace) amounts in the diet to maintain health. For example, copper, selenium, and iodine are considered trace elements.
a chronic obstructive pulmonary (lung) disease, characterized by damage to the small air sacs (alveoli) and difficulty breathing. Damage to the alveoli decreases their elasticity and results in hyperinflation of the lungs, which impairs gas exchange. Smoking is the most common cause of emphysema.
the hard, white, outermost layer of a tooth.
either of two optical isomers that are mirror images of each other.
a disease of the brain that alters brain function.
the addition of nutrients to replace losses that may occur in food processing.
a cell that lines the luminal (inner) surface of the intestine.
a biological catalyst; that is, a substance that increases the speed of a chemical reaction without being changed in the overall process. Enzymes are vitally important to the regulation of the chemistry of cells and organisms.
a study examining disease occurrence in a human population.
the outer layers of skin above the dermis. The epidermis consists of overlapping layers of keratinocytes in various stages of development, eventually forming the barrier that protects underlying cell layers from the environment.
a system of tubules emerging from the testes, which serves as a storage site for sperm during their maturation.
also known as seizure disorder. Individuals with epilepsy experience seizures, which are the result of uncontrolled electrical activity in the brain. A seizure may cause a physical convulsion, minor physical signs, thought disturbances, or a combination of symptoms.
layer of cells that lines a body cavity or covers an external surface of the body.
reddening of the skin; often used as an indice of inflammation caused by ultraviolet exposure.
a hormone produced by specialized cells in the kidneys that stimulates the bone marrow to increase the production of red blood cells. Recombinant erythropoietin is used to treat anemia in patients with end stage renal failure.
the portion of the gastrointestinal tract that connects the throat (pharynx) to the stomach.
the product of a reaction between a carboxylic acid and an alcohol that involves the elimination of water. For example a cholesterol ester is the product of a reaction between a fatty acid and cholesterol.
a hormone that binds to estrogen receptors in the nuclei of cells and promotes the transcription of estrogen-responsive genes. Endogenous estrogens are steroidhormones produced by body. Exogenous estrogens are synthetic or natural compounds that have estrogenic activity (i.e., bind the estrogen receptor and promote estrogen-responsive gene transcription).
an organic acid molecule consisting of a chain of carbon molecules and a carboxylic acid (-COOH) group. Fatty acids are found in fats, oils, and as components of a number of essential lipids, such as phospholipids and triglycerides. Fatty acids can be burned by the body for energy.
a portion of the thighbone (femur). The femoral neck is found near the hip, at the base of the head of femur, which makes up the ball of the hip joint. Fractures of the femoral neck sometimes occur in individuals with osteoporosis.
a newborn of birth weight >4,000 grams (>8 pounds 13 ounces).
an anaerobic process that involves the breakdown of dietary components to yield energy.
a cell that secretes extracellular matrix proteins, such as collagen, which give skin its structure. These cells are mostly found in the dermis and connective tissue.
Fibrocystic breast changes (FCC)
a benign (noncancerous) condition of the breasts, characterized by lumpiness and discomfort in one or both breasts.
a phenomenon of drug metabolism whereby the concentration of a drug is greatly reduced before it reaches the systemic circulation due to action from the gastrointestinal tract and liver.
Food frequency questionnaire
a method of dietary assessment in which study participants are given a validated list of food and beverages and asked to report the frequency and portion size consumed over a given period of time.
Forced expiratory volume (FEV1)
the volume of air that can be expelled during the first second of a forced expiration. FEV1 is used to assess pulmonary (lung) function.
the addition of nutrients to foods to prevent or correct a nutritional deficiency.
a break in a bone or cartilage, often but not always the result of trauma.
a very reactive atom or molecule typically possessing a single unpaired electron.
describes a group of circulating proteins that have become irreversibly bound to glucose. Fructosamine assays provide information about blood glucose control two to three weeks prior to sample collection.
a very sweet six-carbon sugar abundant in plants. Fructose is increasingly common in sweeteners such as high-fructose corn syrup.
a small sac adjacent to the liver. The gallbladder stores bile, which is secreted by the liver, and releases it into the small intestine through the common bile duct.
crystals formed by the precipitation of cholesterol or bilirubin in the gallbladder. Gallstones may be asymptomatic (without symptoms) or they may result in inflammation and infection of the gallbladder.
pertaining to the stomach.
a mucus membrane lining of the interior of the stomach that protects the underlying stomach tissue.
inflammation of the lining of the stomach.
Gastroesophageal reflux disease (GERD)
a condition in which stomach contents, including acid, back up (reflux) into the esophagus, causing inflammation and damage to the esophagus. GERD can lead to scarring of the esophagus and may increase the risk of cancer of the esophagus in some patients.
referring to or affecting the digestive tract, which includes the mouth, pharynx (throat), esophagus, stomach, and intestines.
a region of DNA that controls a specific hereditary characteristic, usually corresponding to a single protein.
the process by which the information coded in genes (DNA) is converted to proteins and other cellular structures. Expressed genes include those that are transcribed to mRNA and translated to protein, as well as those that are only transcribed to RNA (e.g., ribosomal and transfer RNAs).
all of the genetic information (encoded in DNA) possessed by an organism.
the genetic makeup of an individual cell or organism.
the period of time between fertilization and birth. In humans, normal gestation is about 40 weeks.
glucose-bound hemoglobin. A test for glycated hemoglobin measures the percentage of hemoglobin that is glucose bound. Since glucose remains bound to hemoglobin for the life of a red blood cell (~120 days), glycated hemoglobin values reflect blood glucose control over the past four months.
Glycemic index (GI)
an index of the blood glucose-raising potential of the carbohydrate in different foods. The GI is calculated as the area under the blood glucose curve after a test food is eaten, divided by the corresponding area after a control food (glucose or white bread) is eaten. The value is multiplied by 100 to represent a percentage of the control food.
Glycemic load (GL)
an index that simultaneously describes the blood glucose-raising potential of the carbohydrate in a food and the quantity of carbohydrate in a food. The GL of a food is calculated by multiplying the GI by the amount of carbohydrate in grams provided by a food and dividing the total by 100.
a large polymer (repeating units) of glucose molecules, used to store energy in cells, especially muscle and liver cells.
the metabolic pathway in the cytosol that degrades glucose, producing energy in the form of ATP.
a compound containing a sugar molecule that can be cleaved by hydrolysis to a sugar and a nonsugar component (aglycone).
enlargement of the thyroid gland. Goiter is one of the earliest and most visible signs of iodine deficiency. The thyroid enlarges in response to persistent stimulation by TSH. In mild iodine deficiency, this adaptive response may be enough to provide the body with sufficient thyroid hormone. However, more severe cases of iodine deficiency result in hypothyroidism. Thyroid enlargement may also be caused by factors other than iodine deficiency, especially in iodine sufficient countries, such as the US.
a substance that induces goiter formation by interfering with thyroidhormone production or utilization.
a condition characterized by abnormally high blood levels of uric acid (urate). Urate crystals may form in joints, resulting in inflammation and pain. Urate crystals may also form in the kidney and urinary tract, resulting in kidney stones. The tendency to develop elevated blood uric acid levels and gout is often inherited.
a genetic disorder resulting in defective absorption of the amino acid, tryptophan.
high-density lipoproteins. HDL transport cholesterol from the tissues to the liver where it can be eliminated in bile. HDL-cholesterol is considered "good cholesterol," because higher blood levels of HDL-cholesterol are associated with lower risk of cardiovascular disease.
the percentage of red blood cells in whole blood.
the branch of medicine that studies the nature, function, disorders, and diseases of the blood, spleen, and lymph glands.
compounds of iron complexed in a characteristic ring structure known as a porphyrin ring.
the process of removing blood from an artery, removing waste products from the blood through dialysis, and returning blood to the body through a vein. Hemodialysis is used to treat end-stage renal failure.
the oxygen-carrying pigment in red blood cells.
the main fraction of glycated (glucose-bound) hemoglobin. Since glucose remains bound to hemoglobin for the life of a red blood cell (~120 days), hemoglobin A1C values reflect blood glucose control over the past four months.
a genetic disorder that results in iron overload despite normal dietary intake of iron.
a hereditary form of anemia characterized by abnormally shaped red blood cells which are spherical and abnormally fragile. The increased fragility of these red blood cells leads to hemolytic anemia (anemia caused by the rupture of red blood cells).
a dimer or complex of two of the same molecule, usually a protein.
having the same appearance, structure, or evolutionary origin.
possessing two identical forms (alleles) of a specific gene.
a chemical released by a gland or a tissue, which affects or regulates the activity of specific cells or organs. Complex bodily functions, such as growth and sexual development, are regulated by hormones.
sensations of heat in the skin, particularly the face, neck, and chest; also known as hot flashes. Hot flushes are most often related to declining estrogen levels during the perimenopause (period surrounding menopause).
Human papilloma virus (HPV)
a group of viruses that may cause papillomas (growths or warts) on the skin or other parts of the body, including the genitals and the larynx (voice box). Infection with particular strains of HPV is associated with increased risk of cervical cancer.
an inherited degenerative disorder of the brain. Its symptoms include movement disorders and impaired cognitive function. Symptoms of Huntington's disease, previously known as Huntington's chorea, typically develop in the fourth decade of life and progressively deteriorate over time.
cleavage of a chemical bond by the addition of water. In hydrolysis reactions, a large compound may be broken down into smaller compounds when a molecule of water is added.
a molecule that has a high affinity for water and will readily dissolve in water.
a molecule that repels water and thus will not dissolve in water.
a calcium phosphate salt. Hydroxyapatite is the main mineral component of bone and teeth and is what gives them their rigidity.
a chemical reaction involving the addition of a hydroxyl (-OH) group to a compound.
an abnormally high blood glucose concentration; symptoms include increased thirst, increased urination, and general fatigue.
excess secretion of parathyroid hormone by the parathyroid glands resulting in the disturbance of calcium metabolism. Symptoms may include increased blood levels of calcium (hypercalcemia), decreased blood levels of phosphorus, loss of calcium from bone, and kidney stone formation.
a surgically created connection between the ileum (part of the small intestine) and an opening in the abdominal wall (stoma) that allows for the evacuation of feces when a portion of the bowel has been removed.
a metabolic state between normal glucose regulation and overt diabetes. Impaired glucose tolerance is defined medically as a plasma glucose concentration between 140 and 199 mg/dL (7.8-11.0 mmol) two hours after the ingestion of 75 g of glucose during an oral glucose tolerance test.
inability to control the evacuation of urine or feces.
initiation of or increase in the expression of a gene in response to a physical or chemical stimulus (inducer).
a response to injury or infection, characterized by redness, heat, swelling, and pain. Physiologically, the inflammatory response involves a complex series of events, leading to the migration of white blood cells to the inflamed area.
a condition characterized by leg pain or weakness on walking that diminishes or resolves with rest. It is usually associated with peripheral arterial disease.
International normalized ratio (INR)
the preferred method for reporting prothrombin time, a measure of coagulation status that may be used to evaluate the therapeutic efficacy of anticoagulants, such as warfarin. The INR is a method for standardizing prothrombin time results so as to minimize variability between laboratories.
an experimental study (usually a clinical trial) used to test the effect of a treatment or intervention on a health- or disease-related outcome.
a yellowish staining of the skin and whites of the eyes due to increased bilirubin (a bile pigment) levels in the blood. Jaundice can be an indicator of red blood cells rupturing (hemolysis), or disease of the liver or gallbladder.
the process of cell differentiation of a keratinocyte through the different layers of the epidermis. At the end of keratinization, the cell is wider and flatter and attached to its neighboring cells by a variety of protein and lipid attachments.
primary cell type of the epidermis; these cells produce the structural protein keratin, which comprise the epidermal barrier.
any of three acidic chemicals (acetate, acetoacetate, and β-hydroxybutyrate). Ketone bodies may accumulate in the blood (ketosis) when the body has inadequate glucose to use for energy and must increase the use of fat for fuel. Ketone bodies are acidic, and very high levels in the blood are toxic and may result in ketoacidosis.
solid masses resulting from the crystallization of minerals and other compounds found in urine. Common types of kidney stones include those composed of calcium oxalate, calcium phosphate and urate. Kidney stones may form in the kidneys, ureters, or urinary bladder.
abnormal thickening of the wall of the left ventricle (lower chamber) of the heart muscle. The ventricles have muscular walls in order to pump blood from the heart through the arteries, but LVH occurs when the ventricle must pump against abnormally high volume or pressure loads. LVH may accompany congestive heart failure (CHF).
members of the large family of plants known as leguminosae. In this context the term refers to the fruit or seeds of leguminous plants (e.g., peas and beans) that are used for food.
the transparent structure inside the eye that focuses light rays onto the retina (the nerve cells at the back of the eye).
an acute or chronic form of cancer that involves the blood-forming organs. Leukemia is characterized by an abnormal increase in the number of white blood cells in the tissues of the body, with or without a corresponding increase of those in the circulating blood, and is classified according to the type of white blood cell most prominently involved.
white blood cell. Leukocytes are part of the immune system. Monocytes, lymphocytes, neutrophils, basophils, and eosinophils are different types of leukocytes.
a lipoprotein particle in which the protein (apolipoprotein B-100) is chemically linked to another protein apolipoprotein(a). Increased blood levels of Lp(a) are associated with an increased risk of cardiovascular disease.
particle composed of lipids and protein that allows for the transport of lipids through the bloodstream. A lipoprotein particle is composed of an outer layer of phospholipids, which renders it soluble in water, and a hydrophobic core that contains triglycerides and cholesterol esters. Different types of lipoproteins are distinguished by their surface proteins (apoproteins), their size, and the types and amounts of lipids they contain.
the portion of the spine between the chest (thorax) and the pelvis. It is commonly referred to as the small of the back.
the channel within a tube such as a blood vessel or the intestine.
leukocyte (white blood cells) that plays important roles in the immune system. T lymphocytes (T cells) differentiate into cells that can kill infected cells or activate other cells in the immune system. B lymphocytes (B cells) differentiate into cells that produce antibodies.
a cellular organelle containing hydrolytic enzymes specialized for breaking down cellular debris. Lysosomal enzymes are separated from the rest of the cell by a lysosomal membrane and function optimally at an acidic pH.
white blood cell that engulfs and degrades pathogens (bacteria) and cellular debris. Macrophages are activated or transformed monocytes.
a small area of the retina where vision is the sharpest. The macula is located in the center of the retina and provides central vision.
Magnetic Resonance Imaging (MRI)
a special imaging technique that uses a powerful magnet and a computer to provide clear images of soft tissues. Tissues that are well-visualized using MRI include the brain and spinal cord, abdomen, and joints.
a disease or condition that results in poor absorption of nutrients from food.
an infectious disease caused by parasitic microorganisms called plasmodia. Malaria can be spread among humans through the sting of certain types of mosquitos (Anopheles) or by a contaminated needle or transfusion. Malaria is a major health problem in the tropics and subtropics, affecting over 200 million people worldwide.
membranous or microfold cells; specialized cells in the intestinal epithelium that internalize pathogenic microorganisms to the gut-associated lymphoid tissue.
the difference between a measured value and its true value.
low red blood cell count, characterized by the presence in the blood of large, immature, nucleated cells (megaloblasts) that are forerunners of red blood cells. Red blood cells, when mature, have no nucleus.
a dark brown pigment found in the skin.
a pigment-containing cell of the epidermis. The pigment, melanin, absorbs ultraviolet light and protects the skin from damage. Unlike keratinocytes, melanocytes are not shed over time.
the electrical potential difference across a membrane. The membrane potential is a result of the concentration differences between potassium and sodium across cell membranes, which are maintained by ion pumps. A large proportion of the body's resting energy expenditure is devoted to maintaining the membrane potential, which is critical for nerve impulse transmission, muscle contraction, heart function, and the transport of nutrients and metabolites in and out of cells.
the cyclic loss of blood by a woman from her uterus (womb) when she is not pregnant. Menstruation generally occurs every four weeks after a woman has reached sexual maturity and prior to menopause.
a statistical technique used to combine the results from different studies to obtain a quantitative estimate of the overall effect of a particular intervention or exposure on a defined outcome.
a combination of medical conditions that places one at risk for cardiovascular disease and type 2 diabetes. (Metabolic syndrome is also called metabolic syndrome X, syndrome X, and insulin resistance syndrome.) Diagnostic criteria include the presence of three or more of the following conditions:
Abdominal obesity (waist circumference: ≥40 inches [102 cm] for men, ≥35 inches [88 cm] for women)
Elevated triglycerides (≥150 mg/dL or on drug treatment for elevated triglycerides)
High blood pressure (≥130 mm Hg for systolic blood pressure and/or ≥85 mm Hg for diastolic blood pressure, or taking anti-hypertensive drugs)
Glucose intolerance/insulin resistance (fasting blood glucose ≥100 mg/dL, or on drug treatment for elevated glucose)
Decreased HDL cholesterol (<40 mg/dL for men and <50 mg/dL for women, or on drug treatment for low HDL cholesterol)
the sum of the processes (reactions) by which a substance is assimilated and incorporated into the body or detoxified and excreted from the body.
a compound derived from the metabolism of another compound is said to be a metabolite of that compound.
to spread from one part of the body to another. Cancer is said to metastasize when it spreads from the primary site of origin to a distant anatomical site.
a biochemical reaction resulting in the addition of a methyl group (-CH3) to another molecule.
an aggregate or cluster of amphipathic molecules in water. Amphipathic molecules have a polar or hydrophilic end and a nonpolar or hydrophobic end. In micelles, amphipathic molecules orient with their hydrophobic ends in the interior and their hydrophilic ends on the exterior surface, exposed to water.
a nutrient required by the body in small amounts, such as a vitamin or a mineral.
a type of headache thought to be related to abnormal sensitivity of blood vessels (arteries) in the brain to various triggers resulting in rapid changes in the artery size due to spasm (constriction). Other arteries in the brain and scalp then open (dilate), and throbbing pain is perceived in the head. The tendency toward migraine appears to involve serotonin, a neurotransmitter that can trigger the release of vasoactive substances in the blood vessels.
nutritionally significant element. Elements are composed of only one kind of atom. Minerals are inorganic, i.e., they do not contain carbon as do vitamins and other organic compounds.
Minimal Erythemal Dose (MED)
the lowest dose of ultraviolet radiation (UVR) that will produce a detectable erythema 24 hours after UVR exposure.
energy-producing structures within cells. Mitochondria possess two sets of membranes: a smooth continuous outer membrane and an inner membrane arranged in folds. Among other critical functions, mitochondria convert nutrients into energy via the electron transport chain.
the process of cell division.
millimeters of mercury. The unit of measure for blood pressure.
a portion of something, such as a functional group of a molecule.
the fundamental unit for measuring chemical compounds (abbreviated mol). One mole equals the molecular weight of a compound in grams. The number of molecules in a mole is equal to 6.02 x 1023 (Avogadro's number).
a class of proteins that facilitates in the folding and assembly of other proteins.
a change in a gene; in other words, a change in the sequence of base-pairs in the DNA that makes up a gene. Mutations in a gene may or may not result in an altered gene product.
the fatty substance that covers myelinated nerves. Myelin is a layered tissue surrounding the axons or nerve fibers. This sheath acts as a conduit in an electrical system, allowing rapid and efficient transmission of nerve impulses.
the formation of the myelin sheath around a nerve fiber.
derived from bone marrow.
Myocardial infarction (MI)
death (necrosis) of heart muscle tissue due to an interruption in its blood supply. Commonly known as a heart attack, an MI usually results from the obstruction of a coronary artery by a clot in people who have coronary atherosclerosis.
a temporary dysfunction of the cardiac myocardium (contractile abormality) following ischemia and reperfusion.
a case-control study within a cohort study; cases of a disease that occur in a defined cohort are identified, and a specified number of matched controls is then selected from the larger cohort for comparison.
Neural Tube Defect (NTD)
a birth defect caused by abnormal development of the neural tube, the structure which gives rise to the central nervous system. Neural tube defects include anencephaly and spina bifida.
the formation and development of nerves, nerve tissue, or the nervous system.
or neurological; involving nerves or the nervous system (brain, spinal cord, and all sensory and motor nerves).
cell of the nervous system that conducts nerve impulses. Also called nerve cell.
nerve damage or disease.
toxic or damaging to nervous tissue (brain and peripheral nerves).
a chemical that is released from a nerve cell and results in the transmission of an impulse to another nerve cell or organ (e.g., a muscle). Acetylcholine, dopamine, norepinephrine, and serotonin are neurotransmitters.
a compound composed of a nitrogen-containing base (adenine, guanine, cytosine, uracil, or thymine) linked to either ribose or deoxyribose.
subunit of nucleic acids. Nucleotides are composed of a nitrogen-containing base (adenine, guanine, cytosine, uracil, or thymine), a five-carbon sugar (ribose or deoxyribose), and one or more phosphate groups.
a study in which no experimental intervention or treatment is applied. Participants are simply observed over time.
relating to the eye.
Odds ratio (OR)
a measure of association comparing the odds of an outcome in the exposed group to the odds of an outcome in the non-exposed (control) group. The OR is an approximation of the relative risk.
the amount of eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) in red blood cell membranes expressed as the percent of total red blood cell membrane fatty acids.
the field of medicine dealing with cancer and tumors.
a biochemical term for functional groups containing only one carbon in addition to other atoms. One-carbon units transferred by folate coenzymes include methyl (-CH3), methylene (-CH2-), formyl (-CH=O), formimino (-CH=NH), and methenyl (-CH=). Many biosynthetic reactions involve the addition of a one-carbon unit to a precursor molecule.
a type of bone cell formed from an osteoblast once it becomes embedded deep within the organic matrix.
a disease of adults that is characterized by softening of the bones due to loss of bone mineral. Osteomalacia is characteristic of vitamin D deficiency in adults, while children with vitamin D deficiency suffer from rickets.
death of bone tissue.
a condition of low bone mass clinically defined as having a T-score one to 2.5 standard deviations (SD) below that of the average young adult (30 years of age) female.
a small organ located behind the stomach and connected to the duodenum (part of the small intestine). The pancreas synthesizesenzymes that help digest food in the small intestine and hormones, including insulin, that regulate blood glucose levels.
a disease of the nervous system caused by degeneration of a part of the brain called the basal ganglia, as well as by low production of the neurotransmitter dopamine. Symptoms include muscle rigidity, tremors, and slow voluntary movement.
the biological mechanisms underlying the development of a disease.
the branch of medicine that studies the causes and effects of disease.
Peptic ulcer disease
a disease characterized by ulcers or breakdown of the inner lining of the stomach or duodenum. Common risk factors for peptic ulcer disease include the use of nonsteroidal anti-inflammatory drugs (NSAIDs) and infection with Helicobacter pylori.
a disease or degenerative state affecting the nerves of the extremities (arms and legs). Symptoms may include numbness, pain, and muscle weakness.
Peripheral vascular disease
atherosclerosis of the vessels of the extremities, which may result in insufficient blood flow or pain in the affected limb, particularly during exercise.
a procedure in which a special dialysis solution is introduced through a tube in the peritoneum. The dialysis solution pulls wastes and extra fluid from the body when the dialysis solution is drained through the same tube. The most common form is called continuous ambulatory peritoneal dialysis and can be performed at home without a machine.
a membrane that lines the walls of the abdominal cavity.
the end stage of an autoimmuneinflammation of the stomach, resulting in destruction of stomach cells by one's own antibodies. Progressive destruction of the cells that line the stomach cause decreased secretion of acid and enzymes required to release food bound vitamin B12. Antibodies to intrinsic factor (IF) bind to IF preventing formation of the IF-B12 complex, further inhibiting vitamin B12 absorption.
positron emission tomography scan. A diagnostic imaging technique that uses a sophisticated camera and computer to produce images of how a person's body is functioning. A PET scan shows the difference between healthy and abnormally functioning tissues.
a specialized cell, such as a macrophage, that engulfs and digests invading microorganisms through the process of phagocytosis.
process by which phagocytes engulf and digest invading microorganisms and foreign particles.
an intracellular vesicle containing the foreign material engulfed by the phagocyte.
the study of the absorption, distribution, metabolism, and elimination of drugs and other compounds.
the dose or intake level of a nutrient many times the level associated with the prevention of deficiency or the maintenance of health. A pharmacologic dose is generally associated with the treatment of a disease state and considered to be a dose at least 10 times greater than that needed to prevent deficiency.
Phase I clinical trial
a clinical trial in a small group of people aimed at determining bioavailability, optimal dose, safety, and early evidence of the efficacy of a new therapy.
Phase II clinical trial
a clinical trial designed to investigate the effectiveness of a new therapy in larger numbers of people and to further evaluate short-term side effects and safety of the new therapy.
Phase III clinical trial
once a drug or treatment has been shown to be efficacious and safe in phase I and II clinical trials, a large, phase III clinical trial must be conducted before the drug or treatment receives formal FDA approval.
a class of chemical compounds consisting of a hydroxyl functional group (-OH) attached to an aromatic hydrocarbon group. An aromatic hydrocarbon has a ring structure like that of benzene. Polyphenolic compounds contain more than one phenolic group.
an inherited disorder resulting in the inability to process the amino acid, phenylananine. If not treated, the disorder may result in mental retardation. Treatment is a diet low in phenylalanine. Newborns are screened for PKU, in order to determine the need for treatment before brain damage occurs.
the removal of blood from a vein. Phlebotomy may be used to obtain blood for diagnostic tests or to treat certain conditions, for example, iron overload in hemochromatosis.
lipid in which phosphoric acid, as well as fatty acids, are attached to a glycerol backbone. Phospholipids are important structural components of cell membranes.
the creation of a phosphate derivative of an organic molecule. This is usually achieved by transferring a phosphate group (-PO4) from ATP to another molecule.
skin damage induced by ultraviolet (UV) light that is absorbed in an uncontrolled manner by molecules in the body. Depending on the dose, UV light can cause cell death and an inflammatory response.
the dose or intake level of a nutrient associated with the prevention of deficiency or the maintenance of health. A physiologic dose of a nutrient is not generally greater than that which could be achieved through a conscientious diet, as opposed to the use of supplements.
biologically active, non-nutrient compound synthesized by plants.
a plant-derived compound with estrogenic activity.
a compound that gives a plant or animal cell color by the selective absorption of different wavelengths of light.
a preliminary study conducted on a small scale in order to prepare for a larger study.
a small oval gland located at the base of the brain that secretes hormones regulating growth and metabolism. The pituitary gland is divided into two separate glands, the anterior and posterior pituitary glands, which each secrete different hormones.
an inert treatment that is given to a control group while the experimental group is given the active treatment. Placebo-controlled studies are conducted to make sure that the results are due to the experimental treatment, rather than another factor associated with participating in the study.
the organ that connects the fetus to the pregnant woman's uterus, allowing for the exchange of oxygen, carbon dioxide, nutrients, and waste between woman and fetus.
premature separation of the placenta from the wall of the uterus. Abruption is a potentially serious problem both for the woman and fetus.
whole blood without blood cells; that is, red blood cells and white blood cells have been removed. Plasma is separated from blood cells using a centrifuge. Unlike serum, plasma retains clotting factors because it is obtained from blood that is not allowed to clot.
irregularly shaped cell fragments that assist in blood clotting.
a disease of the lungs characterized by inflammation and accumulation of fluid in the lungs. Pneumonia may be caused by infectious agents (e.g., viruses or bacteria) or by inhalation of certain irritants.
a large molecule formed by combining many similar smaller molecules (monomers) in a regular pattern.
a nucleotide difference (variant) in the DNA sequence of a gene. Most polymorphisms are harmless and are part of normal human genetic variation, but some polymorphisms affect the function of the gene product (protein).
a benign (non-cancerous) mass of tissue that forms on the inside of a hollow organ, such as the colon.
a molecule which is an ingredient, reactant, or intermediate in a synthetic pathway for a particular product.
a condition characterized by a sharp rise in blood pressure during the third trimester of pregnancy. High blood pressure may be accompanied by edema (swelling) and proteinuria (protein in the urine). In some cases, untreated preeclampsia can progress to eclampsia, a life-threatening situation for the woman and child.
the proportion of a population with a specific disease or condition at a given point in time.
live cultures of microorganisms that, when administered in sufficient amounts, benefits the overall health of the host.
prevention, often refers to a treatment used to prevent a disease.
Prospective cohort study
an observational study in which a group of people—known as a cohort—are interviewed or tested for risk factors (e.g., nutrient intake), and then followed up at subsequent times to determine their status with respect to a disease or health outcome.
a gland in men, located at the base of the bladder and surrounds the urethra. The prostate produces fluid that forms part of semen. If the prostate becomes enlarged it may exert pressure on the urethra and cause urinary symptoms. Prostate cancer is one of the most common types of cancer in men.
Prostate-specific antigen (PSA)
a compound normally secreted by the prostate that can be measured in the blood. If prostate cancer is developing, the prostate secretes larger amounts of PSA. Blood tests for PSA are used to screen for prostate cancer and to follow up on prostate cancer treatment.
a complex organic molecule composed of amino acids in a specific order. The order is determined by the sequence of nucleic acids in a gene coding for the protein. Proteins are required for the structure, function, and regulation of the body's cells, tissues, and organs, and each protein has unique functions.
a large compound comprised of protein and polysaccharide units known as glycosaminoglycans (GAGs). GAGs are polymers of sugars and amino sugars, such as glucosamine or galactosamine. Proteoglycans are integral components of structural tissues like bone and cartilage.
an elementary particle identical to the nucleus of a hydrogen atom, which along with neutrons, is a constituent of all other atomic nuclei. A proton carries a positive charge equal and opposite to that of an electron.
a chronic skin condition often resulting in a red, scaly rash located over the surfaces of the elbows, knees, scalp, and around or in the ears, navel, genitals, or buttocks. Approximately 10-15% of patients with psoriasis develop joint inflammation (psoriatic arthritis). Psoriasis is thought to be an autoimmune condition.
Pyruvate kinase deficiency
a hereditary deficiency of the enzyme pyruvate kinase. Pyruvate kinase deficiency results in hemolytic anemia.
a mixture of equal amounts of isomers that are mirror images of each other (enantiomers).
the local use of radiation to destroy cancer cells or stop them from dividing and growing.
Randomized controlled trial (RCT)
a clinical trial with at least one active treatment group and a control (placebo) group. In RCTs, participants are chosen for the experimental and control groups at random and are not told whether they are receiving the active or placebo treatment until the end of the study. This type of study design can provide evidence of causality.
an experiment in which participants are chosen for the experimental and control groups at random, in order to reduce bias caused by self-selection into experimental and control groups. This type of study design can provide evidence of causality.
recommended dietary allowance. Established by the Food and Nutrition Board of the US Institute of Medicine, the RDA is the average daily dietary intake level of a nutrient sufficient to meet the requirements of nearly all healthy individuals in a specific life stage and gender group.
Reactive nitrogen species (RNS)
highly reactive chemicals, containing nitrogen, that react easily with other molecules, resulting in potentially damaging modifications.
Reactive oxygen species (ROS)
highly reactive chemicals, containing oxygen, that react easily with other molecules, resulting in potentially damaging modifications.
a type of measurement error caused by inaccuracies in the recollection of study participants regarding past behaviors and experiences.
a specialized molecule inside or on the surface of a cell that binds a specific chemical (ligand). Ligand binding usually results in a change in activity within the cell.
a trait that is expressed only when two copies of the gene responsible for the trait are present.
the last portion of the large intestine, connecting the sigmoid colon (above) to the anus (below). The rectum stores stool until it is evacuated from the body.
another term for an oxidation-reduction reaction. A redox reaction is any reaction in which electrons are removed from one molecule or atom and transferred to another molecule or atom. In such a reaction one substance is oxidized (loses electrons) while the other is reduced (gains electrons).
a chemical reaction in which a molecule or atom gains electrons.
a rapid process of cell growth by which the epidermis repairs itself after a wounding event. The goal of reepithelialization is to re-establish a functional barrier that protects underlying cells from environmental exposures.
Relative Risk (RR)
the probability of a negative outcome in the exposed group divided by the probability of the negative outcome in the non-exposed (control) group.
refers to the kidneys.
in nutrition, having fulfilled nutrient requirements.
results when investigators fail to completely control for confounders by adjustment in statistical analyses.
the process of breaking down or assimilating something. With respect to bone, resorption refers to the breakdown of bone by osteoclasts, resulting in the release of calcium and phosphate (bone mineral) into the blood.
a sequence of nucleotides in a gene that can be bound by a protein. Proteins that bind to response elements in genes are sometimes called transcription factors or binding proteins. Binding of a transcription factor to a response element regulates the production of specific proteins by inhibiting or enhancing the transcription of genes that encode those proteins.
a concept that refers to the counterintuitive direction in a cause-and-effect association, when it is the effect that influences the cause; E.g., if low vitamin D status is common in people affected by multiple sclerosis (MS), it might be because those with MS spend less time outdoors and therefore synthesize less vitamin D in their skin (reverse causation), rather than because poor vitamin D status increases the risk of MS.
a chronic autoimmune disease characterized by inflammation of the synovial lining of the joints. Rheumatoid arthritis may also affect other organs of the body, including the skin, eyes, lungs, and heart.
a molecule consisting of a five-carbon sugar (ribose), a nitrogen-containing base, and one or more phosphate groups.
often the result of vitamin D deficiency. Rickets affects children while their bones are still growing. It is characterized by soft and deformed bones and is the result of an impaired incorporation of calcium and phosphate into the skeleton.
the probability of a negative outcome occurring.
ribonucleic acid; a single-stranded nucleic acid composed of many nucleotides. The nucleotides in RNA are composed of a nitrogen-containing base (adenine, guanine, cytosine, or uracil), a five-carbon sugar (ribose) and a phosphate group. RNA functions in the translation of the genetic information encoded in DNA to proteins.
a fatty acid with no double bonds between carbon atoms.
Scavenge (free radicals)
to combine readily with free radicals, preventing them from reacting with other molecules.
a debilitating brain disorder that affects about 1% of the world’s population. Symptoms may include hallucinations, delusions, thought disorders, disorders of movement, cognitive deficits, lack of emotional expression, or impaired ability to speak, plan, and interact with others. Although its cause is not known, schizophrenia is thought to result from a combination of genetic and environmental factors.
a disorder caused by lack of vitamin C. Symptoms include anemia, bleeding gums, tooth loss, joint pain, and fatigue. Scurvy is treated by supplying foods high in vitamin C, as well as with vitamin C supplements.
gland found at the base of hair follicles that secretes sebum.
whole blood without clotting factors. Serum is separated from blood cells using a centrifuge. Unlike plasma, serum lacks clotting factors because it is obtained from blood that has been allowed to clot.
a hereditary disease in which a mutation in the gene for one of the proteins that comprises hemoglobin results in the formation of defective hemoglobin molecules known as hemoglobin S. Individuals who are homozygous for this mutation (possess two genes for hemoglobin S) have red blood cells that change from the normal discoid shape to a sickle shape when the oxygen supply is low. These sickle-shaped cells are easily trapped in capillaries and damaged, resulting in severe anemia. Individuals who are heterozygous for the mutation (possess one gene for hemoglobin S and one normal hemoglobin gene) have increased resistance to malaria.
a group of anemias that are all characterized by the accumulation of iron deposits in the mitochondria of immature red blood cells. These abnormal red blood cells do not mature normally, and many are destroyed in the bone marrow before reaching the circulation. Sideroblastic anemias can be hereditary, idiopathic (unknown cause), or caused by such diverse factors as certain drugs, alcohol, or copper deficiency.
Signal transduction pathway
a cascade of events that allows a signal outside a cell to result in a functional change inside the cell. Signal transduction pathways play important roles in regulating numerous cellular functions in response to changes in a cell’s environment.
a sleep disorder characterized by repeated cessation of breathing.
the part of the digestive tract that extends from the stomach to the large intestine. The small intestine includes the duodenum (closest to the stomach), the jejunum, and the ileum (closest to the large intestine).
capable of being dissolved.
the polyol (sugar alcohol) corresponding to glucose.
a birth defect, also known as a neural tube defect, resulting from failure of the lower end of the neural tube to close during embryonic development. Spina bifida, the most common cause of infantile paralysis, is characterized by a lack of protection of the spinal cord by its membranes and vertebral bones.
also known as celiac sprue and celiac disease, it is an inherited disease in which the intestinal lining is inflamed in response to the ingestion of a protein known as gluten. Treatment of celiac disease involves the avoidance of gluten, which is present in many grains, including wheat, rye, oats, and barley. Inflammation and atrophy of the lining of the small intestine leads to impaired nutrient absorption.
the state of nutrition of an individual with respect to a specific nutrient. Diminished or low status indicates inadequate supply or stores of a specific nutrient for optimal physiological functioning.
the accumulation of fat in the liver.
obstruction or narrowing of a passage. Coronary stenosis refers specifically to obstruction or narrowing of a coronary artery, which supplies blood to the heart muscle (myocardium).
a molecule related to cholesterol. Many important hormones, such as estrogen and testosterone, are steroids.
Steroid hormone receptor
a protein within a cell which binds to a specific steroid hormone. Binding of the steroid hormone changes the shape of the receptor protein and activates it, allowing it to activate gene transcription. In this way, a steroid hormone can activate the synthesis of specific proteins.
the outer layer of skin; consists of corneocytes that are connected by various proteins and lipids to form a tight barrier around underlying tissue.
a hairline or microscopic break in a bone, usually due to repetitive stress rather than trauma. Stress fractures are usually painful, and may be undetectable by X-ray. Although they may occur in almost any bone, common sites of stress fractures are the tibia (lower leg) and metatarsals (foot).
damage that occurs to a part of the brain when its blood supply is suddenly interrupted (ischemic stroke) or when a blood vessel ruptures and bleeds into the brain (hemorrhagic stroke). A stroke is also called a cerebrovascular accident (CVA).
without clinical signs or symptoms; sometimes used to describe the early stage of a disease or condition, before symptoms are detectable by clinical examination or laboratory tests.
a structured review of the literature designed to answer a clearly formulated question. Systematic reviews use systematic and explicitly predetermined methods to identify, select and critically evaluate research relevant to the question, and to collect and analyze data from the studies that are included in the review. Statistical methods, such as meta-analysis, may be used to summarize the results of the included studies.
Systemic lupus erythematosus (SLE)
a chronic autoimmune disease characterized by inflammation of the connective tissue. SLE is more common in women than men and may result in inflammation and damage to the skin, joints, blood vessels, lungs, heart, and kidneys.
Systolic blood pressure
the highest arterial pressure measured during the heart beat cycle, and the first number in a blood pressure reading (e.g., 120/80).
an agent that interferes with normal development of an embryo or fetus.
one-third of a sample or population.
a condition of prolonged and painful spasms of the voluntary muscles, especially the fingers and toes (carpopedal spasm), as well as the facial musculature.
Beta thalassemia is a genetic disorder that results in abnormalities of the globin (protein) portion of hemoglobin. An individual who is homozygous for the β thalassemia gene (has two copies of the β thalassemia gene) is said to have thalassemia major. Infants born with thalassemia major develop severe anemia a few months after birth, accompanied by pallor, fatigue, poor growth, and frequent infections. Blood transfusions are used to treat thalassemia major but cannot cure it.
Individuals who are heterozygous for the β thalassemia gene (carry one copy of the β thalassemia gene) are said to have thalassemia minor or thalassemia trait. These individuals are generally healthy but can pass the β thalassemia gene to their children and are said to be carriers of the β thalassemia gene.
the process of controlling body temperature to prevent both excessive cooling and warming.
the point at which a physiological effect begins to be produced, for example, the degree of stimulation of a nerve which produces a response or the level of a chemical in the diet that results in a disease.
a butterfly-shaped gland in the neck that secretes thyroid hormones. Thyroid hormones regulate a number of physiologic processes, including growth, development, metabolism, and reproductive function.
the most common form of thyroid cancer, which most often affects women of childbearing age. Thyroid papillary cancer has a lower rate of recurrence and metastases (spreading to other organs) than thyroid follicular cancer.
applied to the skin or other body surface.
Total Parenteral Nutrition (TPN)
intravenous (I.V.) feeding that provides patients with essential nutrients when they are too ill to eat normally.
a condition caused by poisoning.
also known as spongy or cancellous bone, the type of bone found within the ends of long bones and inside flat bones and spinal vertebrae.
(DNA transcription); the process by which one strand of DNA is copied into a complementary sequence of RNA.
a protein that functions to initiate, enhance, or inhibit the transcription of a gene. Transcription factors can regulate the formation of a specific protein encoded by a gene.
hydrogenated or partially hydrogenated oils.
Transient ischemic attack (TIA)
sometimes called a small or mini stroke. TIAs are caused by a temporary disturbance of blood supply to an area of the brain, resulting in a sudden, brief (usually less than one hour) disruptions in certain brain functions.
trembling or shaking of a part or all of the body.
lipid consisting of three fatty acid molecules bound to a glycerol backbone. Triglycerides are the principal form of fat in the diet, although they are also synthesized endogenously. Triglycerides are stored in adipose tissue and represent the principal storage form of fat. Elevated serum triglycerides are a risk factor for cardiovascular disease.
a hereditary disorder characterized by increased urinary excretion of trimethylamine, a compound with a “fishy” or foul odor.
an infection caused by bacteria called mycobacterium tuberculosis. Many people infected with tuberculosis have no symptoms because it is dormant. Once active, tuberculosis may cause damage to the lungs and other organs. Active tuberculosis is also contagious and is spread through inhalation. Treatment of tuberculosis involves taking antibiotics and vitamins for at least six months.
an infectious disease spread by the contamination of food or water supplies with the bacteria called salmonella typhi. Food and water can be contaminated directly by sewage or indirectly by flies or poor hygiene. Though rare in the US, it is common in some parts of the world. Symptoms include fever, abdominal pain, diarrhea, and a rash. It is treated with antibiotics and intravenous fluids. Vaccination is recommended to those traveling to areas where typhoid is common.
tolerable upper intake level. Established by the Food and Nutrition Board of the US Institute of Medicine, the UL is the highest level of daily intake of a specific nutrient likely to pose no risk of adverse health effects in almost all individuals of a specified age.
a chronic inflammatory disease of the colon and rectum. Symptoms of ulcerative colitis include abdominal pain, cramping, and bloody diarrhea.
a test in which high-frequency sound waves (ultrasound) are bounced off tissues and the echoes are converted into a picture (sonogram).
Unsaturated fatty acid
a fatty acid with at least one double bond between carbons.
an excessive concentration of urea and other nitrogenous waste products in the blood that are normally excreted by the kidneys.
a chemical compound that is foreign to the organism. Xenobiotics may include dietary factors, toxins, pharmaceuticals, and pollutants.
a series of enzymatic reactions that convert a foreign chemical compound into an inert substance that can be safely excreted from the body. The three phases of xenobiotic metabolism include: (i) activation, (ii) functionalization, and (iii) efflux.
a transplant of tissue from a donor of one species to a recipient of another species.
a rare disorder caused by a tumor called a gastrinoma, most often occurring in the pancreas. The tumor secretes the hormone gastrin, which causes increased production of gastric acid leading to severe recurrent ulcers of the esophagus, stomach, and the upper portions of the small intestine.