The process of nutrients traveling from the lumen of the GI tract to the blood or lymph after digestion.

acceptable macronutrient distribution ranges (AMDR)

The calculated range of how much energy from carbohydrate, fat, and protein is recommended for a healthy diet.

accessory organs

Organs that are not part of the intestinal tract itself, but have ducts that deliver digestive juices into the tract to help aid in digestion; includes the salivary glands, liver, gallbladder, and pancreas.

acetyl CoA

An important molecule for many metabolic pathways, including the Krebs Cycle in aerobic metabolism.

active vitamin A

Another term for retinol found in animal-derived foods.

added sugars

Concentrated sweeteners that are added as ingredients to foods to make them sweeter; they decrease a food's nutrient density.

adenosine triphosphate (ATP)

The energy-containing molecule found in the cells of all animals and humans; powers cellular work.


Providing sufficient amounts of calories and each essential nutrient, as well as fiber.

adequate intake (AI)

Nutrient recommendations set when there is not enough evidence to establish an RDA; based on observing healthy people and seeing how much of the nutrient in question they are consuming.

aerobic exercise

Continuous exercise (lasting more than 2 minutes) that increases heart and breathing rate (e.g., walking, jogging, biking) and primarily relies on energy generated through aerobic metabolism.

aerobic metabolism

The metabolic pathways that require oxygen to generate ATP for cells.

air displacement plethysmography (ADP)

A non-invasive, quick, but more expensive tool to estimate body composition by measuring air displacement when a person sits in an enclosed chamber.


Butterfly-shaped protein; has many functions in the body including maintaining fluid and acid-base balance and transporting molecules.


A foreign substance that causes an immune response in the body.

alpha-linolenic acid

An essential omega-3 fatty acid.

amino acids

The building blocks of protein.


Molecules that are both water- and fat-soluble.

anabolic pathways

The synthesis of larger molecules, which requires energy.

anaerobic exercise

Activities that consist of short duration, high intensity movements that rely on immediately available energy sources and require little or no oxygen during the activity.

anaerobic metabolism

The metabolic system that can generate ATP without oxygen.


A severe allergic reaction involving more than one organ system (e.g., a rash coupled with difficulty breathing).


A condition in which oxygen-carrying capacity of red blood cells is reduced, often from a reduction in hemoglobin.


A negatively-charged electrolyte (e.g., chloride).

anorexia nervosa

An eating disorder in which a person obsesses about their weight and the food that they eat, resulting in extreme nutrient inadequacy and eventually organ malfunction.

anorexia of aging

A condition that is characterized by poor food intake, which results in dangerous weight loss in older adults.

antibiotic resistance

When bacteria develop resistance to antibiotics, and the antibiotics no longer work to kill the bacteria causing infections.


Proteins that circulate in blood, recognize harmful intruders like bacteria and viruses, and surround and destroy them.


Molecules that can donate an electron to stabilize and neutralize free radicals.


Found on the surface of lipoproteins; both fat- and water-soluble.


The psychological desire to eat.


Occurs when food flows into the respiratory tract and can result in pneumonia.


The narrowing of arteries due to buildup of plaque.


The fundamental unit of matter; the smallest unit of an element.

authorized health claims

Claims that have stronger scientific evidence to back them than qualified health claims.

autoimmune diseases

A disease where the immune system produces antibodies that attack and damage the body’s own tissues.


Including a combination of foods from the different food groups.

basal metabolic rate (BMR)

The energy expended by the body when at rest, to fuel the behind-the-scenes activities required to sustain life (e.g., respiration, circulation); largest component of energy expenditure.

behavioral weight loss interventions

Interventions that help individuals develop skills that support healthy lifestyle and body weight.


A type of carotenoid; a precursor to active vitamin A.


A chemical made by the liver and stored in the gallbladder; acts as an emulsifier, which allows fat droplets to mix with the watery digestive juices in the small intestine.

binge-eating disorder

An eating disorder characterized by periodic overeating with a feeling of loss of control over eating but not accompanied with fasting, purging, or compulsive exercise.


The amount of a substance that is absorbed from the intestine into the bloodstream.

bioelectric impedance analysis (BIA)

A simple, non-invasive, quick tool that estimates body composition by sending a small amount of electricity through the body.

biological macromolecules

The raw materials used to build living organisms; formed when atoms of carbon, hydrogen, oxygen, and nitrogen bond with each other in unique and varied ways.


technique to prevent bias in intervention studies, where either the research team, the subject, or both don’t know what treatment the subject is receiving.

body composition

The proportion of fat and fat-free mass (includes bones, muscles, and organs) in your body; one of the four essential elements of physical fitness.

body mass index (BMI)

A simple formula expressing the ratio of body weight and height; an inexpensive screening tool used in clinical and research settings to estimate body size and health risk.


What food is referred to once it has been chewed and moistened.

bone mineral density (BMD)

A test that can detect osteoporosis and predict the risk of bone fracture.


The outer skin of a wheat kernel; contains antioxidants, B vitamins, and fiber.

brush border

Another name for microvilli, because their appearance resembles the bristles on a brush.


An eating disorder characterized by episodes of eating large amounts of food followed by purging, which is accomplished by vomiting and with the use of laxatives and diuretics.


A precursor to the active form of vitamin D; the circulating form of vitamin D and the form measured in blood to assess a person’s vitamin D status.


A hormone secreted by the thyroid gland; decreases blood calcium levels.


Activated vitamin D; increases the absorption of calcium in the intestine and works with PTH to release calcium from bone and reduce calcium loss in urine.


Macromolecules composed of carbon, hydrogen, and oxygen; major fuel source for all cells of the body.

cardiorespiratory endurance

Physical fitness developed through aerobic exercise, which strengthens the heart and lungs and reduces the risk of cardiovascular disease; one of the four essential elements of physical fitness.


Brightly-colored yellow, orange, and red pigments synthesized by plants.

case-control studies

Research that compares a group of cases and controls, looking for differences between the two groups that might explain their different health outcomes.

catabolic pathways

The breakdown of complex molecules into simpler molecules to generate energy.


A positively-charged electrolyte (e.g., sodium).

celiac disease

An autoimmune disorder; the body has an abnormal immune reaction to gluten; results in damage to the villi, decreasing the surface area for nutrient absorption.

cell membrane

A thin covering around the cell that separates the internal and external environments.


The smallest structural and functional units of all living things.

cellular differentiation

The process by which cells change from stem cells to more specialized cells with specific structure and function.

cellular respiration

A key pathway of energy metabolism occurring in cells of aerobic organisms; results in the production of ATP.


One of the most common types of fiber; the main component in plant cell walls.

chemical bond

The attractive force between atoms; contains energy.

chemical digestion

The breakdown of macronutrients into their chemical building blocks (e.g., starch into glucose) with the aid of enzymes.


Also known as vitamin D3, this type of vitamin D is made by the skin when exposed to UV light and found in animal-derived foods.

cholecystokinin (CCK)

A hormone that is secreted in response to nutrients in the gut, especially fat and protein, and signals satiety; aids in nutrient digestion by inhibiting food intake and stimulating pancreatic secretions, gall bladder contractions, and intestinal motility.


The most well-known sterol; only found in animal fats.

cholesterol esters

Cholesterol molecules with a fatty acid attached; part of the structure of lipoproteins.


A type of lipoprotein that serves as a transport vehicle for lipids absorbed from the small intestine into lymph and blood.


A semiliquid mass of partially digested food and gastric juices.


An enzyme made by the pancreas; facilitates the chemical breakdown of proteins in the small intestine.


Also known as clotting; the process by which blood changes from a liquid to a semi-liquid or gel to form a clot.


Organic molecules required by enzymes to catalyze a specific reaction.


Inorganic minerals that assist in enzymatic reactions.

cohort studies

Research that follows a group of people (a cohort) over time, measuring factors such as diet and health outcomes.


A protein important to the strength and structure of muscles, bones, tendons, ligaments, connective tissue, and skin.


Breast milk produced in small quantities for the first two to five days after the birth of the baby; low in fat, easily digestible, rich in protein, fat-soluble vitamins, and minerals, as well as immunoglobulins that provide immune protection to the newborn.

compact bone

Also known as cortical bone, this dense bone tissue surrounds all spongy bone and makes up approximately 80 percent of the adult skeleton.

complementary feeding

The time in later infancy when solid foods are added to the baby’s diet, while breastmilk and/or formula continue to be the nutritional foundation of the diet.

complementary proteins

Two or more incomplete protein sources that can be combined to make a complete protein.

complete protein source

A food that contains all of the essential amino acids in adequate amounts needed by the body.

complete proteins

A high-quality protein that contains all 9 essential amino acids; found in animal foods and soy and quinoa.

complex carbohydrates

Large carbohydrates that contain many sugar units, also called polysaccharides; include starch, glycogen, and fiber.

conditionally essential amino acids

Amino acids that must be obtained in the diet in certain situations when more are needed than the body can synthesize.

confounding factors

Factors that can affect the outcome in question.

connective tissue

A tissue that connects, supports, and/or binds other tissues in the body.


Infrequent bowel movements (less than 3 times per week); stools that are hard, dry, or lumpy, and often painful to pass.


Relationships between two factors (e.g., nutrition and health).

covalent bond

The strongest, most stable type of chemical bond in the biological world, made from the sharing of electrons.

creatine phosphate

A high-energy molecule that can be used to generate ATP for cells during the first 10 seconds of an activity.

Crohn’s disease

A chronic inflammatory disease that can affect any part of the GI tract.

cross-sectional studies

Research that collects information about a population of people at one point in time.


The cellular fluid within a cell.

daily value (DV)

An approximate recommendation for daily intake for a nutrient, developed by the FDA for use on food labels; allows consumers to see how much of a nutrient is provided by a serving of a food relative to about how much they need each day.


A process that removes nitrogen from amino acids before they are used to synthesize ATP, glucose, or fat.


A significant water loss in the body, such that the body doesn’t have enough fluids to function properly.


When the three-dimensional structure of a protein is unfolded due to a change in the environment (e.g., acid, heat); results in loss of protein function.


A chronic disease in which the body isn’t able to regulate blood glucose; includes type 1, type 2, and gestational diabetes.


Loose, watery stools.

dietary fiber

Non-digestible carbohydrates that are found in plants.

dietary habits

Routines such as what a person eats, how much a person eats, how frequently meals are consumed, and how often a person eats out.

dietary reference intakes (DRI)

A set of recommendations developed by the National Academies of Sciences, Engineering, and Medicine to describe the amounts of specific nutrients and energy that people should consume in order to stay healthy.

dietary supplement

A product that is intended to supplement the diet and can be taken by mouth; contains one or more dietary ingredients (e.g., vitamins, minerals, herbs or other botanicals, amino acids, or enzymes).


A healthcare professional who has registered credentials (requiring a bachelor’s or master’s degree in dietetics, completion of a dietetic internship, passing a national exam, and maintenance of registration through ongoing continuing education) and can provide nutritional care in the areas of health and wellness.


A simple carbohydrate that contains two sugar units; includes maltose, sucrose, and lactose.

docosahexaenoic acid (DHA)

An important omega-3 fatty acid that can be synthesized in the body; helps lower blood triglycerides and blood pressure, reduce inflammation, prevent blood clot formation, and promote normal growth and development in infants.


Neither the research team nor the subject know what treatment the subject is receiving.

dual energy X-ray absorptiometry (DXA)

One of the most accurate but more expensive methods of measuring body composition; this method scans the body with low-dose X-ray beams to determine fat, muscle, and bone mass.


The first segment of the small intestine.


Difficulty swallowing.

eating competence

An evidence-based model developed by Ellyn Satter; based on the principle that internal cues of hunger, appetite, and satiety are reliable and can be used to inform food selection and guide energy balance and body weight.


A large family of important signaling molecules, with roles such as regulating inflammation.

eicosapentaenoic acid (EPA)

An important omega-3 fatty acid that can be synthesized in the body; it helps lower blood triglycerides and blood pressure, reduce inflammation, prevent blood clot formation, and promote normal growth and development in infants.


A protein that gives connective tissue its elasticity and flexibility.


Substances that dissociate into charged ions when dissolved in water (e.g., sodium chloride (NaCl) dissociates into sodium (Na+) and chloride (Cl−) in water).


Small, negative particles that are found outside of the nucleus of an atom in regions called shells.


Substance made entirely from one specific type of atom.

empty calories

Calories from solid fats and/or added sugars, adding few other nutrients; make foods less nutrient dense.


Chemicals that allow fat to mix with watery liquids.

endoplasmic reticulum

An organelle that processes and packages proteins and lipids for transport.


A procedure in which a camera is inserted into the GI tract to visualize the interior.


The largest part of the wheat kernel; provides energy in the form of starch to support reproduction.

energy balance

When energy intake equals energy expenditure; weight should remain stable.

energy metabolism

The process of converting food into energy.


Nutrients that provide energy to the body; include carbohydrates, proteins, and fats.


Food ingredients with added nutrients; usually refined grains that have lost naturally-occurring nutrients during processing.


Absorptive cells that line the small intestine.


Proteins that help speed up or facilitate chemical reactions in the body; they bring together two compounds to react, without undergoing any changes themselves.

epithelial tissue

A tissue that lines and protects organs.


Also known as vitamin D2, this type of vitamin D is made by plants, mushrooms, and yeast.

ergogenic aids

Substances used to enhance performance.


A muscular tube that transports food from the mouth to the stomach.

essential amino acids

Amino acids that must be obtained in the diet because they can’t be synthesized by the body in sufficient amounts.

essential fatty acids

Fatty acids that can’t be synthesized in the body and must be consumed in the diet.

estimated average requirement (EAR)

The amount of a nutrient that meets the requirements of 50 percent of people within a group of the same life stage and sex.

estimated energy requirement (EER)

An estimate of how many calories a person needs to consume, on average, each day to stay healthy, based on their age, sex, height, weight, and physical activity level.


The final step of digestion; undigested materials are removed from the body.

exercise-related activity thermogenesis (EAT)

Planned, structured, and repetitive physical activity with the objectives such as improving health or fitness or having fun (e.g., strength training, sports).

extracellular fluid (ECF)

The fluid outside of cells; includes both blood plasma and interstitial fluid.

fat-soluble vitamins

Vitamins that dissolve in fat; include vitamins A, D, E, and K.

fatty acids

Long chains of carbon and hydrogen molecules with an acid (-COOH) at one end.


Undigested materials that are stored in the anus until they are excreted from the body.


A storage form of iron.


A polysaccharide made by plants to provide protection and structural support.


A helpful tool for putting together an exercise plan that includes considering the frequency, intensity, time, and type of exercise.


Physical fitness developed through stretching and other activities, enhancing the ability of joints to move through the full range of motion; one of the four essential elements of physical fitness.


A condition caused by excessive intake of fluoride; characterized by mottling (i.e., white speckling) and pitting of the teeth.

folic acid

A synthetic form of folate.


A substance, usually derived from plants, animals, or fungi, that is consumed and provides nutrients.

food allergy

The result of the immune system mistakenly identifying a food protein as an invasive threat; usually causes immediate symptoms, such as rash, swollen face or throat, or difficulty breathing.

food deserts

Areas where healthy foods simply aren’t available or easily accessible.

food insecurity

Having inconsistent access to enough food for an active, healthy life.

food intolerance

Occurs when a person has difficulty digesting a specific food or nutrient (due to missing a specific digestive enzyme); symptoms include unpleasant GI symptoms such as gas, bloating, flatulence, cramping, and diarrhea.

food security

Having consistent access to enough food for an active, healthy life.

free radical

An atom or group of atoms with an unpaired electron; they are unstable, highly reactive, and can be damaging in excess.


A component of the FITT acronym that describes how often you exercise.


A monosaccharide that is one of the sweetest sugars; found in fruits, vegetables, honey, and high fructose corn syrup.


A monosaccharide that is rarely found in food alone, but found in dairy products bonded to glucose.


An accessory organ located behind the liver; stores, concentrates, and secretes bile.

gastric lipase

An enzyme produced by cells of the stomach; aids in the chemical breakdown of triglycerides.

gastroesophageal reflux (GER)

When the acidic chyme in the stomach escapes back into the esophagus.

gastroesophageal reflux disease (GERD)

A disease diagnosis when heartburn occurs more than twice a week.

gene expression

The process by which the instructions contained in DNA are used to synthesize a product such as a protein.


The embryo of the seed, which can sprout into a new plant; contains B vitamins, protein, minerals, and healthy fats.

gestational diabetes

A type of diabetes that develops during pregnancy in women who did not previously have diabetes.


Known as the “hunger hormone”; produced in the stomach and communicates hunger to the brain.

GI tract

A one-way tube about 25 feet in length, beginning at the mouth and ending at the anus; where digestion takes place.


A hormone made by the pancreas and released when blood glucose is low; it causes glycogen in the liver to break down, results in raising blood glucose concentrations.


The synthesis of new glucose molecules from amino acids.


A monosaccharide that is a product of photosynthesis and an important fuel source for the body; found in fruits and vegetables, honey, corn syrup, and high fructose corn syrup.


A group of proteins found in wheat, rye, and barley; in people with celiac disease, gluten causes antibodies to attack the cells lining the small intestine.


The three-carbon backbone of triglycerides.


A polysaccharide made up of long, branched chains of glucose; a storage form of carbohydrate in animals.


A cycle that occurs in the cytoplasm of the cell and plays a central role in the production of energy through anaerobic metabolism.

golgi apparatus

An organelle that distributes macromolecules like proteins and lipids around the cell.


The state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.

Health at Every Size (HAES)

An approach that aims to decrease our culture’s obsession with body size and weight, decrease weight discrimination and stigma, and instead promote size acceptance and inclusivity.

health claims

Statements on food packaging that link the food or a component in the food to reducing the risk of a disease.


A burning, often painful, sensation in the chest or throat; caused by gastroesophageal reflux.

helicobacter pylori (H. pylori)

Bacteria that cause peptic ulcers.

heme iron

Iron that is part of the proteins hemoglobin and myoglobin; most bioavailable form of iron, found only in animal foods.


A protein in red blood cells that transports oxygen to cells and gives red blood cells their color.


Excessive bleeding.

high-density lipoproteins (HDL)

A type of lipoprotein that picks up cholesterol from the body’s cells and returns it to the liver for disposal; sometimes called “good cholesterol,” because high blood levels are associated with a lower risk of cardiovascular disease.


The body’s ability to maintain equilibrium or a steady state, such as maintaining blood glucose concentration.


An amino acid found in blood.


Chemical messengers that are produced by endocrine glands and travel in the blood to target cells to initiate a specific reaction or cellular process.


The physiological need to eat.

hydrochloric acid

An acid that is a component of gastric juices; creates an acidic environment in the stomach, killing bacteria and aiding in protein digestion.


The process of adding hydrogen to the carbon-carbon double bonds of a fatty acid, thus making it more saturated.


The splitting of one molecule into two with the addition of water; the main chemical reaction in digestion.


Tiny crystals made from inorganic minerals that form around collagen fibers to provide strength to bones.


Chemical reactions that add a hydroxyl (-OH) group to a compound.


High blood calcium.


High blood sugar.


Thickening of the outer layer of the skin due to overproduction of the protein keratin; can be a symptom of vitamin A deficiency.


An elevated level of lipids, including triglycerides and cholesterol, in the blood.


Elevated blood sodium concentration.


High blood pressure.

hypochromic anemia

A type of anemia characterized by low color red blood cells.


Low blood sugar.


Low blood sodium concentration.


The final segment of the small intestine, where the majority of absorption occurs.

immunoglobulin E (IgE)

A type of antibody produced by the immune system in response to a specific substance.

in vitro study

Experiments that are conducted outside of living organisms, within flasks, dishes, plates, or test tubes.

in vivo

Research that is conducted in living organisms, such as rats and mice.

incomplete protein source

A food that does not contain all of the essential amino acids in adequate amounts needed by the body.

incomplete proteins

A lower quality protein that does not contain all 9 essential amino acids in proportions needed to support growth and health; found in plant foods.

inflammatory bowel disease (IBD)

Includes two types of disorders — ulcerative colitis and Crohn’s disease.


The first process of digestion; the entry of food into the GI tract through the mouth.


Nutrients that do not contain both carbon and hydrogen; can not be created or destroyed.

insoluble fiber

A type of fiber that does not typically dissolve in water and helps prevent constipation; lignin, cellulose, and hemicellulose are common types of insoluble fibers, and food sources include wheat bran, vegetables, fruits, and whole grains.


A hormone made by the pancreas and released when blood glucose is high; it results in lowering blood glucose concentrations.

insulin resistance

A condition where cells stop responding to insulin.


A component of the FITT acronym that describes how hard you work during your exercise session.

intermediate-density lipoproteins (IDL)

A type of lipoprotein that is created as triglycerides are removed from VLDL.

interstitial fluid (IF)

The fluid that surrounds cells.

intervention studies

Research that includes some type of treatment or change imposed by the researchers; sometimes called experimental studies or clinical trials.

intracellular fluid (ICF)

The fluid contained within cells.

intrinsic factor

A protein secreted in the stomach that is necessary for vitamin B12 absorption.

iron-deficiency anemia

A condition that develops from having insufficient iron levels in the body, resulting in fewer and smaller red blood cells that contain less hemoglobin.

irritable bowel syndrome (IBS)

A type of functional GI disorder that is caused by a disruption in the signals between the brain and gut; symptoms include abdominal pain, bloating, the feeling of not being able to finish a bowel movement, as well as diarrhea or constipation or both, often in cycles.

junk science

Untested or unproven claims or ideas, usually meant to push an agenda, sell a product, or promote special interests.


A strong, fibrous protein; an important component of skin, hair, and nails.


A condition which results from too many ketones accumulating in the blood, resulting in the blood being too acidic.

ketone bodies

Another name for ketones.


Compounds that are made when fatty acid breakdown is high and glucose is limited.


The accumulation of ketones in the blood.

krebs cycle

A cycle that occurs in the mitochondria of cells and plays a central role in the production of energy through aerobic metabolism.


A protein deficiency characterized by swelling of the feet and abdomen, poor skin health, poor growth, low muscle mass, and liver malfunction.


An enzyme produced by the enterocytes; breaks lactose into its building blocks, glucose and galactose.


A disaccharide made of a glucose molecule bonded to a galactose molecule; found in dairy products like milk, yogurt, and cheese.

lactose intolerance

A common food intolerance; not enough of the enzyme lactase is produced to effectively digest the milk sugar lactose.

large intestine

The part of the GI tract that lies between the small intestine and the anus; water absorption occurs here.


A hormone produced by adipose tissue; its production increases as fat stores increase, and it communicates to the brain to suppress hunger and increase energy expenditure.

lingual lipase

An enzyme produced by cells on the tongue; begins the chemical breakdown of triglycerides.

linoleic acid

An essential omega-6 fatty acid.


A group of enzymes that facilitate the chemical breakdown of triglycerides.

lipid panel

A standard blood test that reports total cholesterol, LDL, HDL, and triglycerides.


A family of organic compounds that are mostly insoluble in water; the three main types are triglycerides, sterols, and phospholipids.

lipoprotein lipase

An enzyme that sits on the surface of cells that line the blood vessels; it breaks down triglycerides, allowing fatty acids and glycerol to enter nearby cells.


Transport vehicles for moving water-insoluble lipids around the body.


An accessory organ located just under the rib cage on the right side of the abdomen; produces bile and helps get rid of toxins.

low-density lipoproteins (LDL)

A type of lipoprotein that delivers cholesterol to the body’s cells; sometimes called “bad cholesterol,” because high blood LDL is a risk factor for atherosclerosis.


The interior space of the GI tract where digestion and absorption occur.


An organelle that breaks down macromolecules and destroys foreign invaders.


An enzyme secreted in the saliva; attacks the walls of bacteria, causing them to rupture.

macrocytic anemia

A type of anemia characterized by larger and fewer red blood cells; caused by folate deficiency.


Nutrients that are needed in large amounts and include carbohydrates, lipids, and proteins.

major minerals

Minerals required by the body in amounts greater than 100 milligrams per day.


A lack of proper nutrition, which can be caused by not getting enough or getting too much food or nutrients.


An enzyme produced by the enterocytes; breaks maltose into two glucose molecules.


A disaccharide made of two glucose molecules bonded together; found in sprouted grains.


A protein and calorie deficiency characterized by an extreme emaciated appearance, poor skin health, poor growth, and increased risk of infection.


Chewing; increases the surface area of the food and allows for food to be broken into small enough pieces to be swallowed safely.


Anything that has mass and takes up space.

mechanical digestion

The physical process of making food particles smaller to increase both surface area and mobility without changing the chemical nature of the food (e.g., mastication and peristalsis).


A type of systematic review that combines data from multiple studies and uses statistical methods to summarize it, as if creating a mega-study from many smaller studies.

metabolic health

The body’s ability to maintain normal homeostasis and effectively regulate measures like blood pressure, blood lipids, and blood glucose.

metabolically healthy obese (MHO)

Individuals that are classified as obese (BMI > 30) but do not experience increased metabolic health risks.

metabolically obese normal weight (MONW)

Individuals who are classified as having a healthy weight (BMI < 25) but have indicators of poor metabolic heatth.


Structures that consist of bile salts clustered around the products of fat digestion; aid in absorption of fats into enterocytes.

microcytic anemia

A type of anemia characterized by small red blood cells.


Nutrients required by the body in smaller amounts; include all of the essential minerals and vitamins.


Hair-like projections that line the enterocytes’ cell membrane to increase surface area.


Inorganic elements classified according to how much the body requires.


An organelle often called the powerhouse of the cell; generates usable energy for the cell from energy-yielding nutrients.


Dismantling of bone tissue at one site and building up at another, changing the shape of the bone.


Avoiding extremes, neither too much nor too little of any one food or nutrient.


A group of two or more atoms held together by chemical bonds.


The smallest of the carbohydrates, containing just one sugar unit; include glucose, fructose, and galactose.

monounsaturated fatty acid

A fatty acid with one double bond.


The oral cavity where ingestion and mastication occur.


A tissue that contracts to provide movement and support.

muscle strength

Physical fitness developed through strength training, which causes muscles to work harder than usual and builds strength; one of the four essential elements of physical fitness.

mutual supplementation

The process of combining complementary proteins.

myelin sheath

A cover that surrounds and protects nerve cells and allows electrical impulses to transmit quickly and efficiently.


A protein similar to hemoglobin but found in muscles; provides oxygen to muscles.

naturally-occurring sugars

Sugars found naturally in foods such as fruits, veggies, and dairy; come packaged with fiber, vitamins, and minerals.

negative energy balance

When energy intake is less than energy expenditure; usually results in weight loss.

negative nitrogen balance

When the amount of excreted nitrogen is greater than that consumed, meaning that the body is breaking down protein to meet its demands.


A tissue that responds and reacts to signals in the environment.


Small, neutral particles that are found in the nucleus of an atom.

night blindness

A condition that makes it difficult to see in low-light conditions.

nitrogen balance

When the amount of nitrogen consumed equals the amount of nitrogen excreted.

non-celiac gluten sensitivity (NCGS)

A diagnosis when people test negative for celiac disease but still believe that consuming gluten is causing symptoms.

non-diet approaches

Approaches that focus on establishing a healthy relationship with food and more body acceptance and positivity regardless of shape and size (e.g: Satter Eating Competence Model, Health at Every Size).

non-exercise activity thermogenesis (NEAT)

Energy expenditure for unstructured and unplanned activities (e.g., daily-living activities like cleaning the house); also includes the energy required to maintain posture and spontaneous movements such as fidgeting and pacing.

non-heme iron

The mineral form of iron by itself, not a part of hemoglobin or myoglobin; found in foods from both plants and animals and is less bioavailable than heme iron.

nonessential amino acids

Amino acids that are not required in the diet because the body can synthesize them.

nonsteroidal anti-inflammatory drugs (NSAIDs)

A classification of drugs such as aspirin or ibuprofen; long-term use is the second leading cause of peptic ulcers.


A membrane-bound organelle within the cell that contains genetic material (DNA).

nutrient claims

Statements regulated by the FDA that provide straight-forward information about the level of a nutrient or calories in the food, such as “fat-free,” “low calorie,” or “reduced sodium.”

nutrient density

A measure of the amount of nutrients provided by a food (especially vitamins, minerals, fiber, protein, and healthy fats) relative to the calories it contains.


Chemical molecules that are found in foods; required by our bodies to maintain life and support growth and health.


The study of how food affects the health of the body.


A title commonly used to imply expertise in nutrition, but this term has no legal regulation; anyone can call themselves a nutritionist with or without proper training.

obesogenic environments

Built environments that promote weight gain by encouraging food intake and limiting physical activity.

observational studies

In nutrition, research that is conducted by collecting information on people’s dietary patterns or nutrient intake to look for associations with health outcomes. Observational studies do not give participants a treatment or intervention; instead, they look at what they’re already doing and see how it relates to their health.

omega-3 fatty acids

Fatty acids with the first double bond at the third carbon from the omega end.

omega-6 fatty acids

Fatty acids with the first double bond at the sixth carbon from the omega end.


A group of similar tissues arranged in a specific manner to perform a specific physiological function (e.g., the heart, the lungs).

organ system

A group of two or more organs that work together to perform a specific physiological function (e.g., the digestive system, the central nervous system).


Tiny organs within the cell that perform a specific task for the cell.


Complex nutrients that can be made by living organisms from many elements (especially carbon, hydrogen, oxygen, and sometimes nitrogen).


The highest level of organization; a complete living system capable of conducting all of life’s biological processes.


An extreme, unhealthy fixation on healthy or “clean” eating.


The diffusion of fluid through a semipermeable membrane toward higher solute concentration.


The process of building new bone.


The cells that are responsible for building new bone.


The cells that are responsible for the breakdown of bone.


A disease caused by a vitamin D deficiency in adults and characterized by softening of bones, reduced bone mineral density, and increased risk of osteoporosis.


Low bone mass, which can lead to osteoporosis if untreated.


A bone disease that occurs when bone density or bone mass decreases, becoming thinner, more porous, and more susceptible to breaking.


The loss of electrons during a reaction.

oxidative stress

Free radical-induced damage that can contribute to disease.


An accessory organ located behind the stomach; produces and secretes pancreatic juices, which contain bicarbonate that neutralizes the acidity of the stomach-derived chyme and enzymes that further break down proteins, carbohydrates, and lipids.

pancreatic amylase

An enzyme secreted from the pancreas into the small intestine; continues the chemical breakdown of starch to smaller glucose chains and maltose.

pancreatic lipases

Enzymes produced by the pancreas; chemically break down triglycerides in the small intestine.

parathyroid glands

Four pea-sized glands located at the back of the thyroid gland; secrete parathyroid hormone.

parathyroid hormone (PTH)

A hormone produced by the parathyroid glands; increases blood calcium levels.

peak bone mass

The point when bones have reached their maximum strength and density.

peer-reviewed manuscripts

Scientific papers that are reviewed by other experts in the field, who were not directly involved in the research, before publication.


An enzyme found in gastric juices; aids in the chemical breakdown of proteins.

peptic ulcers

Sores on the tissues lining the esophagus, stomach, or duodenum.

peptide bond

A special chemical bond between two amino acids.


Sequential, alternating waves of contraction and relaxation of the smooth muscles in the GI tract; acts to propel food along the GI tract.

pernicious anemia

A type of macrocytic anemia caused by vitamin B12 malabsorption due to lack of intrinsic factor.


A lipid that is both water- and fat-soluble due to the hydrophilic phosphate “head,” and the hydrophobic lipid “tail.”


A biological process that captures energy originating from sunlight and converts it to glucose that all organisms use to power daily functions.

physical activity

As a component of total energy expenditure, includes both exercise-related activity thermogenesis (EAT) and non-exercise activity thermogenesis (NEAT); contributes anywhere from 15 to 30 percent of energy expenditure.


The compounds found in plants that give them their smell, taste, and color; some have been shown to affect human health.


An intense craving for and ingestion of non-food items such as paper, dirt, or clay.


A “fake” treatment that contains no active ingredients, such as a sugar pill.

placebo effect

The beneficial effect that results from a subject's belief in a treatment, not from the treatment itself.


An organ that develops during pregnancy; provides nutrition and respiration, handles waste from the fetus, and produces hormones important to maintaining the pregnancy.


The fluid component of the blood.


Fragments of cells that circulate and assist in blood clotting.

polyunsaturated fatty acid

A fatty acid with two or more double bonds.

positive energy balance

When energy intake is greater than energy expenditure; usually results in weight gain.

positive nitrogen balance

When the amount of excreted nitrogen is less than what is consumed, such as during pregnancy or growth in childhood, times the body requires more protein to build new tissues.


A condition that involves insulin resistance, but not full-blown type 2 diabetes.

preformed vitamin A

Another term for retinol found in animal-derived foods.

primary structure

One-dimensional polypeptide chain of amino acids.


Looking into the future.


Enzymes that aid in the chemical breakdown of proteins in the small intestine.

protein folding

The third major step of protein synthesis; the amino acid chain folds into three-dimensional shapes.


Macromolecules composed of chains of amino acids, which are simple subunits made of carbon, oxygen, hydrogen, and nitrogen.


Small, positive particles that are found in the nucleus of an atom.


A substance that can be converted into the active form of a vitamin (e.g., beta-carotene is a provitamin to active vitamin A).


A 3-carbon molecule that is the end product of glycolysis.

qualified health claims

Claims that have some evidence to support them, but not as much, so there’s less certainty that these claims are true.

quaternary structure

Multiple folded polypeptides called subunits that have combined to make one larger functional protein.

randomized controlled trial (RCT)

The gold standard for intervention studies, because the research involves a control group and participants are randomized.

recommended daily allowances (RDA)

Nutrient recommendations that are set to meet the needs of the vast majority (97 to 98 percent) of the target healthy population.


The last part of the GI tract; serves as a temporary holding area for feces.

red blood cells

Also known as erythrocytes; transport oxygen to cells and remove carbon dioxide from cells.

refined grains

Grains and grain products made only from the endosperm.


Degrading and building up of bone tissue at the same location.


The breakdown of bone.


Breathing; taking in oxygen and removing carbon dioxide.

responsive feeding

An approach to feeding that is responsive to the child’s cues; the caregiver recognizes child cues and responds promptly and appropriately.


The form of vitamin A found in animal-derived foods.


Looking at what happened in the past.


A pigment in the eye that is especially important to vision in low-light conditions.


An organelle that assembles proteins based on the instructions of DNA.


A disease caused by vitamin D deficiency in children and characterized by soft, weak, and deformed bones.


A mixture of water, enzymes, and other chemicals secreted from the salivary glands into the mouth.

salivary amylase

A digestive enzyme produced by the salivary glands; starts the chemical breakdown of starch or amylose.

salivary glands

The glands that make and secrete saliva.


A physiological trait that causes blood pressure to increase with a high-sodium diet.


The feeling of being full.

Satter eating competence model

A model developed by Ellyn Satter; focuses on eating attitudes, food acceptance, regulation of food intake and body weight, and management of the eating context.

saturated fatty acid

Fatty acids in which each carbon is bonded to two hydrogen atoms, with single bonds between the carbons.

scientific method

An organized process of inquiry used in nutritional science, and every other science; made up of a cyclical process of steps including observation/question, hypothesis, experiment, analysis, and conclusion.


A disease caused by vitamin C deficiency.

secondary structure

Polypeptide chain that has folded into two-dimensional simple coils (also called helices) and sheets.


Consists of localized contractions of circular muscle of the GI tract; isolates small sections of the intestine, moving contents back and forth while continuously subdividing, breaking up, and mixing the contents; mixes food with digestive juices and facilitates absorption.

selectively permeable

Allowing some substances but not others to pass through freely (e.g., cell membranes allow water to cross, but other substances require special transport proteins, channels, and often energy).

simple carbohydrates

Small carbohydrate molecules made up of just one (monosaccharides) or two (disaccharides) sugar units.

single-blind study

Either the research team or the subject know what treatment is being given, but not both.

skinfold test

A simple, non-invasive, and low-cost way to assess fat mass; calipers are used to measure the thickness of skin on three to seven different parts of the body, and these numbers are then entered into a conversion equation.

small intestine

A part of the GI tract that lies between the stomach and the large intestine; where most digestion and nutrient absorption occurs.

social determinants of health

Economic and social circumstances, such as poverty and racism, that impact health.

soluble fiber

A type of fiber that dissolves in water and helps to decrease blood glucose spikes and lower blood cholesterol levels; pectins and gums are common types of soluble fibers, and good food sources include oat bran, barley, nuts, seeds, beans, lentils, peas, and some fruits and vegetables.


A dissolved substance in a solution.

spina bifida

A neural tube defect that occurs in a developing fetus when the spine does not completely enclose the spinal cord; caused by folate deficiency.

spongy bone

Also known as trabecular bone, this porous, lattice-like bone tissue makes up about 20 percent of the adult skeleton and is found at the ends of long bones, in the cores of vertebrae, and in the pelvis.


A polysaccharide made up of long chains of glucose; a storage form of carbohydrate in plants.


Lipids that have a multi-ring structure.


An expansion of the GI tract that links the esophagus to the first part of the small intestine; aids in both mechanical and chemical breakdown of food.

structure-function claims

Vague statements about nutrients playing some role in health processes; not regulated by the FDA.

subcutaneous fat

Fat stored just underneath the skin.


An enzyme produced by the enterocytes; breaks sucrose into its building blocks, glucose and fructose.


A disaccharide made of a glucose molecule bonded to a fructose molecule; found in fruits, vegetables, table sugar, maple syrup, and honey.

sugar alcohols

A type of sugar substitute; include sorbitol, mannitol, lactitol, erythritol, and xylitol.

sugar substitutes

Artificial, non-nutritive, high-intensity, or low-calorie sweeteners.

sweat rate

The amount of fluids lost through sweat during exercise; it is calculated by measuring weight before and after exercise and is useful for determining hydration needs.

systematic review

Researchers formulate a research question and then systematically and independently identify, select, evaluate, and synthesize all high-quality evidence from previous research that relates to the research question.

tertiary structure

Polypeptide chain that has folded into a three-dimensional organized shape based on the interactions of the amino acids.


A condition in which muscles can’t relax, and instead become stiff and contract involuntarily; caused by calcium deficiency.

The Division of Responsibility

The gold standard approach to feeding children, defining the optimal relationship between parent and child when it comes to feeding: the parent determines the what, where, and when of feeding, and the child chooses how much to eat and whether to eat from the foods provided.

thermic effect of food (TEF)

The energy needed to digest, absorb, and store the nutrients in foods; accounts for 5 to 10 percent of total energy expenditure.

thyroid gland

A small, butterfly-shaped gland located at the base of the neck; secretes hormones that influence metabolism.


A component of the FITT acronym that describes how long you exercise for.


A group of many similar cells that share a common structure and work together to perform a specific function.

tolerable upper intake level (UL)

The highest level of continuous intake of a particular nutrient that may be taken without causing health problems.

total energy expenditure (TEE)

The sum of daily caloric expenditure; includes basal metabolic rate (BMR), thermic effect of food (TEF), and physical activity.

trace minerals

Minerals required by the body in amounts of 100 milligrams or less per day.

trans fatty acid

A fatty acid where the hydrogen atoms are bonded on opposite sides of the carbon chain, resulting in a more linear structure.


The first major step of protein synthesis; a process in which the genetic code of DNA is copied into messenger RNA.


The transport protein for iron.


The second major step of protein synthesis; information on messenger RNA is translated into building a protein.


The main form of lipids in the body and in foods; made up of three fatty acids bonded to a glycerol backbone.


An enzyme that facilitates the chemical breakdown of protein in the small intestine; activates other protein-digesting enzymes.


A component of the FITT acronym that describes what kind of exercise you do.

type 1 diabetes

An autoimmune disease in which the cells of the pancreas that create insulin are destroyed.

type 2 diabetes

The most common type of diabetes, occurring when cells stop responding to insulin; strongly associated with abdominal obesity.

ulcerative colitis

A chronic inflammatory disease specific to the large intestine and rectum.

unsaturated fatty acids

Fatty acids that have one or more points of unsaturation, or double bonds, between the carbons.


Consuming different foods within each of the food groups on a regular basis.


A strict vegetarian who consumes no animal products.

very-low-density lipoprotein (VLDL)

A type of lipoprotein that is made in the liver and delivers triglycerides to the body’s cells.


Tiny, finger-like projections that cover the lining of the small intestine to increase surface area.

visceral fat

Fat surrounding vital organs and stored deep within the abdominal cavity.


Essential, non-caloric, organic micronutrients that are required for many bodily functions.

waist circumference

A measurement of waist size, taken just above the hip bone and level with the belly button and used to assess abdominal fat; waist circumferences greater than 40 inches for men and 35 inches for women are associated with greater health risks.

waist-to-hip ratio

The ratio of waist and hip circumference (at its widest part), used to estimate abdominal fat; abdominal obesity is defined by the World Health Organization as waist-to-hip ratio above 0.90 for males and 0.85 for females.


One of the most vital nutrients; composed of two hydrogens and one oxygen per molecule of water.

water-soluble vitamins

Vitamins that dissolve in water; include vitamin C and all of the B vitamins.

weight bias

Negative attitudes, beliefs, assumptions and judgments toward individuals based on their body size.

white blood cells

Also known as leukocytes; immune cells that help destroy foreign invaders.

whole grains

Grains and grain products made from the entire grain seed, including the bran, germ, and endosperm.


Abnormal dry eyes and clouded vision, usually caused by vitamin A deficiency.


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Nutrition: Science and Everyday Application, v. 1.0 Copyright © 2020 by Alice Callahan, PhD; Heather Leonard, MEd, RDN; and Tamberly Powell, MS, RDN is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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