| nutrients | Chemical substances in food that
contribute to health, many of which are
essential parts of a diet. Nutrients nourish us
by providing calories to fulfill energy needs,
materials for building body parts, and factors
to regulate necessary chemical processes in
the body.
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| stroke | A decrease or loss in blood flow to
the brain that results from a blood clot or
other change in arteries in the brain. This in
turn causes the death of brain tissue. Also
called a cerebrovascular accident.
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| carbohydrate | A compound containing
carbon, hydrogen, and oxygen atoms. Most
are known as sugars, starches, and fibers.
lipid A compound containing much carbon
and hydrogen, little oxygen, and sometimes
other atoms. Lipids dissolve in ether or benzene,
but not in water, and include fats, oils,
and cholesterol.
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| protein | Food and body components made
of amino acids; proteins contain carbon,
hydrogen, oxygen, nitrogen, and sometimes
other atoms, in a specific configuration.
Proteins contain the form of nitrogen most
easily used by the human body.
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| vitamin | Compound needed in very small
amounts in the diet to help regulate and
support chemical reactions in the body.
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| mineral | Element used in the body to
promote chemical reactions and to form
body structures.
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| water | The universal solvent; chemically, H2O.
The body is composed of about 60% water.
Water (fluid) needs are about 9 (women) or
13 (men) cups per day; needs are greater if
one exercises heavily.
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| atom | Smallest combining unit of an element,
such as iron or calcium. Atoms consist of
protons, neutrons, and electrons.
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| element | A substance that cannot be
separated into simpler substances by
chemical processes. Common elements in
nutrition include carbon, oxygen, hydrogen,
nitrogen, calcium, phosphorus, and iron.
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| glucose | A six-carbon monosaccharide that
exits in a ring form; found as such in blood,
and in table sugar bound to fructose; also
known as dextrose, it is one of the simple
sugars.
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| macronutrient | A nutrient needed in gram
quantities in a diet.
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| micronutrient | A nutrient needed in milligram
or microgram quantities in a diet.
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| cell | A minute structure; the living basis of
plant and animal organization. In animals it is
bounded by a cell membrane. Cells contain
both genetic material and systems for synthesizing
energy-yielding compounds. Cells have
the ability to take up compounds from and
excrete compounds into their surroundings.
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| bond | A linkage formed by the sharing of
electrons, or attractions between two atoms.
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| fiber | Substances in plant foods that are not
digested by the processes that take place in
the human stomach or small intestine. These
add bulk to feces. Fiber naturally found in
foods is also called dietary fiber.
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| triglyceride | The major form of lipid in the
body and in food. It is composed of three
fatty acids bonded to glycerol, an alcohol.
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| fatty acid | Major part of most lipids; primarily
composed of a chain of carbons flanked by
hydrogen.
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| saturated fatty acid | A fatty acid
containing no carbon-carbon double bonds.
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| unsaturated fatty acid | A fatty acid
containing one or more carbon-carbon double
bonds.
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| trans fatty acids | A form of an unsaturated
fatty acid, usually a monounsaturated one
when found in food, in which the hydrogens
on both carbons forming that double bond
lie on opposite sides of that bond, rather than
on the same side (typical of fatty acids). Stick
margarine, shortenings, and deep fat-fried
foods in general are rich sources.
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| enzyme | A compound that speeds the rate of
a chemical process but is not altered by the
process. Almost all enzymes are proteins
(some are made of genetic material).
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| amino acid | The building block for proteins
containing a central carbon atom with
nitrogen and other atoms attached.
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| chemical reaction | An interaction between
two chemicals that changes both chemicals.
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| organic | Any substance that contains carbon
atoms bonded to hydrogen atoms in the
chemical structure.
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| inorganic | Any substance lacking carbon
atoms bonded to hydrogen atoms in the
chemical structure.
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| electrolytes | Substances that separate into
ions in water and, in turn, are able to conduct
an electrical current. These include sodium,
chloride, and potassium.
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| solvent | A liquid substance in which other
substances dissolve.
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| metabolism | Chemical processes in the body
by which energy is provided in useful forms
and vital activities are sustained.
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| genes | A specific segment on a chromosome.
Genes provide the blueprints for the production
of cell proteins.
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| alcohol | Ethyl alcohol or ethanol (CH3CH2OH).
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| compound | A group of different types of
atoms bonded together in definite proportion.
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| ion | An atom with an unequal number of
electrons and protons. Negative ions have
more electrons than protons; positive ions
have more protons than electrons.
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| hunger | The primarily physiological (internal)
drive to find and eat food, mostly regulated
by innate cues to eating.
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| appetite | The primarily psychological (external)
influences that encourage us to find and
eat food, often in the absence of obvious
hunger.
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| satiety | State in which there is no longer a
desire to eat; a feeling of satisfaction.
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| hypothalamus | A region at the base of the
brain that contains cells that play a role in the
regulation of hunger, respiration, body
temperature, and other body functions.
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| gastrointestinal (GI) tract | The main sites
in the body used for digestion and absorption
of nutrients. It consists of the mouth,
esophagus, stomach, small intestine, large
intestine, rectum, and anus. Also called the
digestive tract.
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| hormone | A compound secreted into the
bloodstream by one type of cells that acts to
control the function of another type of cells.
For example, certain cells in the pancreas
produce insulin, which in turn acts on muscle
and other types of cells to promote uptake of
nutrients from the blood.
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| endorphins | Natural body tranquilizers that
may be involved in the feeding response.
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| ghrelin | A hormone made by the stomach
that increases the desire to eat.
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| neuropeptide Y | A chemical substance
made in the hypothalamus that stimulates
food intake. The hormone leptin inhibits
neuropeptide Y production.
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| leptin | A hormone made by adipose tissue
in proportion to total fat stores in the body
that influences long-term regulation of fat
mass. Leptin also influences reproductive
functions, as well as other body processes,
such as release of the hormone insulin.
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| adipose tissue | A group of fat storing cells.
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| serotonin | A neurotransmitter synthesized
from the amino acid tryptophan that affects
mood (sense of calmness), behavior, and
appetite, and induces sleep.
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| cholecystokinin (CCK) | A hormone that participates
in enzyme release from the pancreas,
bile release from the gallbladder, and hunger
regulation.
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| hypotheses | "Educated guesses" by a
scientist to explain a phenomenon.
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| pellagra | A deficiency disease characterized
by inflammation of the skin, diarrhea, and
eventual mental incapacity; results from an
insufficient amount of the vitamin niacin in
the diet.
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| experiments | Tests made to examine the
validity of a hypothesis.
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| theory | An explanation for a phenomenon
that has numerous lines of evidence to
support it.
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| ulcer | Erosion of the tissue lining, usually in
the stomach (gastric ulcer) or the upper small
intestine (duodenal ulcer). As a group these
are generally referred to as peptic ulcers.
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| microorganism | Bacteria, virus, or other
organism that is invisible to the naked eye,
some of which cause diseases. Also called
microbes.
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| scurvy | The deficiency disease that results
after a few weeks to months of consuming a
diet that lacks vitamin C; pinpoint sites of
bleeding on the skin are an early sign.
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| epidemiology | The study of how disease
rates vary among different population groups.
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| infectious disease | Any disease caused by
invasion of the body by microorganisms, such
as bacteria, fungi, or viruses.
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| incidence | The number of new cases of a disease
in a defined population over a specific
period of time, such as 1 year.
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| animal model | Study of disease in animals
that duplicates human disease. This can be
used to understand more about human
disease.
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| case-control study | Individuals who have
the condition in question, such as lung cancer,
are compared with individuals who do not
have the condition.
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| double-blind study | An experimental design
in which neither the participants nor the researchers
are aware of each participant’s assignment
(test or placebo) or the outcome of
the study until it is completed. An independent
third party holds the code and the data
until the study has been completed.
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| control group | Participants in an experiment
who are not given the treatment being tested.
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| placebo | Generally a fake medicine used
to disguise the treatments given to the
participants in an experiment.
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| peer-reviewed journal | A journal that
publishes research only after two or three
scientists who were not part of the study
agree it was well conducted and the results
are fairly represented. Thus, the research has
been approved by peers of the research team.
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| megadose | Intake of a nutrient beyond estimates
of needs or what would be found in a
balanced diet; 3 to 10 times human needs is a
starting point.
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| registered dietitian (R.D.) | A person who
has completed a baccalaureate degree
program approved by the American Dietetic
Association, performed at least 900 hours of
supervised professional practice, and passed a
registration examination.
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