Routledge encyclopedia of social and cultural anthropology

1175 Pages·2010·377.38 MB·English

by  Alan Barnard

©1995 CRC Press LLC
©1995 CRC Press LLC
Dedicated to—
the global advancement of food, nutrition, and health
for the benefit of humankind
©1995 CRC Press LLC
About the Authors
Audrey H. Ensminger, whose expertise is human nutrition, is Adjunct Professor, California State University-
Fresno. She (1) completed the B.S. degree in Home Economics, University of Manitoba, Canada, and the M.S.
degree in Home Economics, Washington State University; (2) taught at the University of Manitoba, the Uni-
versity of Minnesota, and Washington State University; and (3) served as dietitian for the U.S. Air Force, at
Washington State University, during World War II. Audrey Ensminger has lectured throughout the world. She
is the senior author of the two widely used human nutrition books, FOODS & NUTRITION ENCYCLOPEDIA
and FOOD FOR HEALTH.
M. E. Ensminger, whose field is nutrition and biochemistry, is President, Agris-
ervices Foundation, a nonprofit foundation serving world agriculture. Dr. Ens-
minger (1) completed B.S. and M.S. degrees at the University of Missouri, and
the PhD. at the University of Minnesota; (2) served on the staffs of the University
of Massachusetts, the University of Minnesota, and Washington State Univer-
sity; and (3) served as Consultant, General Electric Company, Nucleonics
Department (Atomic Energy Commission). Dr. Ensminger is the author or co-
author of 21 widely used books that are in several languages and used through-
out the world. Dr. Ensminger is Adjunct Professor, California State University-
Fresno; Adjunct Professor, the University of Arizona-Tucson; and Distinguished
Professor, the University of Wisconsin-River Falls.
James L. Konlande completed the B.A. degree at Brooklyn College, Brooklyn,
NY; and the M.S. and Ph.D. degrees at Rutgers University, New Brunswick, NJ,
with a major in physiology, biochemistry and nutrition. Prior to co-authoring
FOODS & NUTRITION ENCYCLOPEDIA he served as (1) Assistant Professor,
Nutrition, the University of Michigan School of Public Health, Ann Arbor, Mich-
igan; and (2) Head, Foods and Nutrition, Winthrop College (The University of
South Carolina), Rock Hill, South Carolina.
John R. K. Robson, M.D. was educated in England. He completed (1) the Bachelor of Medicine (M.B.) and
Bachelor of Surgery (B.S.) degrees at Durham University, Kings College Medical School, (2) the Diploma in
Tropical Medicine and Hygiene (D.T.M.&H. Edin.), Edinburgh University Medical School; (3) Diploma in Pub-
lic Health—Special subject Nutrition (D.P.H. London), London University; and (4) the Doctor of Medicine
(M.D.) at the University of Newcastle on Tyne, Medical School, and he is a Certified Specialist in Clinical
Nutrition, American Board of Nutrition. Dr. Robson has done human nutrition work throughout the world.
Also, he served as Professor of nutrition and Director of Nutrition Program, School of Public Health, Univer-
sity of Michigan; and as Professor of Nutrition and Medicine, Medical University of South Carolina, Charles-
ton; and Executive Editor, Ecology of Food and Nutrition—and international journal. He is a Fellow of the
Royal Society of Tropical Medicine and Hygiene; and a member of the New York Academy of Sciences, the
Nutrition Society of Great Britain, the Scientific Council Population Food Fund, and the American Society of
Parenteral and Enteral Nutrition.
©1995 CRC Press LLC
PREFACE
True to its title, THE CONCISE ENCYCLOPEDIA OF FOODS AND NUTRITION covers the whole gamut of the three-pronged
subject—foods-health-nutrition. A simple definition of each of these terms follows:
A food is any material that is taken or absorbed into the body of an organism for the purpose of satisfying
hunger, growth, maintenance, tissue repair, reproduction, work, or pleasure.
Health is the state of complete physical, mental, and social well-being.
Nutrition is the science of food and its nutrients and their relation to health.
IT'S FOR CONSUMERS—ALL
THE CONCISE ENCYCLOPEDIA OF FOODS AND NUTRITION is for all consumers—for everyone who seeks good health, and
for those who counsel with them—physicians, dentists, nutritionists, health experts, and others in allied fields. It's for teachers and
students. It's for those who produce, process, and market foods. It's for those who wish to know the "why" of foods and nutrition—
for those who wish to be educated rather than indoctrinated. It's for those who want the facts—both the pros and cons—on which
they may base a judgment. It's for those who wish to know from whence their food comes—from field to table. It's for those who
are concerned with getting the most nutrition from their food dollars. It's for those who desire authoritative and pleasurable read-
ing about foods and nutrition, and their relationship to health.
AUTHORITATIVE
The authoritativeness of a work is evidenced by the credentials of those who created it. THE CONCISE ENCYCLOPEDIA OF
FOODS AND NUTRITION is the team effort of four well-known professionals in the field of foods-health-nutrition.
TOPICS COVERED
The selection of the topics that are covered in THE CONCISE ENCYCLOPEDIA OF FOODS AND NUTRITION was based on
the authors' professional experiences and perceptions relative to the needs of consumers, with application to many related fields,
including medicine, dentistry, nursing, dietetics, teaching, nutritional science, public health, athletics, homemaking, and food pro-
duction, processing, distribution and marketing. As the authors selected and treated each of the subjects, they were guided by the
simple question: "Is it helpful?" If the answer was in the affirmative, they proceeded with the philosophy of "let the chips fall where
they may," no matter how complex or how controversial the subject. Also, the authors were ever aware that some contemporary
interests are transient; so, they strived to achieve a balance between the timely and the timeless.
COMPREHENSIVENESS
The comprehensiveness of THE CONCISE ENCYCLOPEDIA OF FOODS AND NUTRITION is indicated by the following sta-
tistics pertaining to it: 1,184 pages; more than 2,700 entries (or topics); more than 1,000 illustrations, of which 96 are in color;
more than 200 tables; more than 1,300 food compositions; and a comprehensive index for easy reference.
It covers all aspects of foods-health-nutrition, with adequate historical and interpretive context. Each article includes all relevant
aspects of the topic. Also, the entries reflect the whole gamut of foods-health-nutrition. There are precious few items an foods and
nutrition not found as a subject entry and/or an index entry in THE CONCISE ENCYCLOPEDIA OF FOODS AND NUTRITION.
EASE OF USE
THE CONCISE ENCYCLOPEDIA OF FOODS AND NUTRITION is organized so that the reader may quickly and easily find the
desired information. This is achieved through—
1. All topics being arranged alphabetically, using the word-by-word system the same system that is used in a dictionary or in a
library card catalog.
2. Cross referencing to related articles, usually at the end of an article, but within the text of an article when it makes for greater
convenience.
3. A comprehensive index, which makes it possible for the reader, easily and quickly, to make a systematic survey of all parts
and locations in THE CONCISE ENCYCLOPEDIA OF FOODS AND NUTRITION pertaining to a given subject, directly or indi-
rectly. Additionally, where more than one reference page is listed in the index for a particular subject, the main section is listed in
bold numbers.
(Continued)
©1995 CRC Press LLC
ALTERNATE NAMES
Alternate names are used wherever appropriate, with each name indexed, so that the article can be located under any of the alter-
nate names; for example—
VITAMIN C (ASCORBIC ACID)
FOOTNOTES
Literature pertaining to new and/or controversial material is documented in footnotes wherever possible.
ACKNOWLEDGMENTS
Authoring and publishing a first class book necessitates a first class supporting staff. So, special appreciation is expressed to the fol-
lowing staff members for their commitment to excellence and adhering to a rigid schedule: Joan Wright who deciphered the
authors' hieroglyphics and put them through a typewriter; Randall and Susan Rapp, Rapp Typographic Service, who typeset the
many changes for the second edition; Margo Williams who prepared the new art that enhances the second edition, and Jean Nel-
son who proofread the copy. Also, we shall be ever grateful to Robin Spencer Palmisano, who at the time of preparing the first edi-
tion was Systems Dietitian, University Hospitals, The Ohio State University, Columbus, Ohio, a very special person and dedicated
professional, who contributed so much to Table F-21 Food Compositions. (Presently, Robin Spencer Palmisano is a lawyer and a
member of the firm of McGlinchey, Stafford, Cellini & Lang, New Orleans, Louisiana.) Further, we are grateful to Ron Bruce, Pres-
ident, Unisoft Systems Associates, 1340 Dublin Road, Columbus, Ohio, 43215, for permission to continue to use Table F-21 Food
Compositions. At appropriate places, due acknowledgment and sincere appreciation is expressed to those who responded so lib-
erally to our call for information and pictures. The unnumbered line drawings in THE CONCISE ENCYCLOPEDIA OF FOODS
AND NUTRITION were created by Dynamic Graphics, Inc.
If THE CONCISE ENCYCLOPEDIA OF FOODS AND NUTRITION ushers a better fed, nourished, and healthier world into the
21st century, the authors will feel amply rewarded.
A. H. Ensminger
M. E. Ensminger
J. E. Konlande
J. R. K. Robson
Clovis, California (March, 1995)
©1995 CRC Press LLC
ABERNETHY BISCUIT ACETO-GLYCERIDES (PARTIAL GLYCERIDE
ESTERS)
A hard biscuit containing caraway seeds, named after an
English surgeon who, in the early 1800s, treated maladies These differ from triglycerides in that either one (or some-
with diet. times two) of the long chain fatty acids attached to the glyc-
erol molecule is replaced by acetic acid. They are nongreasy
ABSORPTION
and have lower melting points than the corresponding triglyc-
erides.
The transfer of a substance through a membrane or the taking
Aceto-glycerides are used in shortenings and spreads, as
in of nutrients or other substances from an outside source;
films for coating foods, and as plasticisers for hard fats.
e.g., the passage of substances into the blood and/or lymph
system from the digestive tract, through the skin, or by way of ACETOIN
the lungs.
• The uptake of water, fat, or other substances by foods. Acetyl methyl carbinol, C4H8O2, precursor of diacetyl,
which imparts the flavor to butter. Acetoin is a product of fer-
(Also see DIGESTION AND ABSORPTION.)
mentation, produced by bacteria during the ripening of cream
ABSORPTION METER for churning and by the action of yeast on diacetyl.
ACETONE
An instrument used to measure the absorption of light, by
which a quantitative measure of a colored substance in a
A substance that gives the breath a fruity odor. It may accu-
solution may be obtained. Many substances, such as minerals,
mulate in the blood, breath, and urine when there is an
vitamins, and amino acids, will react with a particular reagent
abnormal metabolism of fats.
to form a colored complex. Since the color developed is pro-
(Also see KETONE BODIES.)
portional to the amount of the substance present, its quantity
may be measured by an absorption meter. ACETONEMIA
ACCLIMATIZE A buildup of acetone in the blood. This condition occurs
only when there is an impairment in breathing. Under normal
The process of becoming adjusted to a new environment, circumstances most acetone is removed from the body via the
especially temperature, altitude, or climate. breath.
ACETATE ACETONURIA
A salt of acetic acid. The name also refers to the metabolic The passing of abnormally large amounts of acetone in the
product called acetylcoenzyme A. urine. This may be a sign of ketosis, which may be brought on
(Also see METABOLISM.) by (1) diets high in fat, and low in carbohydrate; (2) starvation;
or (3) diabetes.
ACETIC ACID (Also see DIABETES MELLITUS; and STARVATION.)
An organic acid which is produced by (1) the metabolism of ACETYLCHOLINE
nutrients, and (2) vinegar fermentation. It reacts with alkalis to
form acetates. A substance released from the ending of certain nerves
(Also see VINEGAR.) which (1) stimulates the digestive functions, and (2) slows the
heart rate and lowers the blood pressure. It is noteworthy that
ACETOACETIC ACID digestive disorders characterized by hypersecretion of diges-
tive juices and spasms of the alimentary tract are often treated
This ketone acid is formed when the quantities of fat which
with medications like atropine and belladonna, which coun-
are burned for energy greatly exceed the amounts of carbohy-
teract acetylcholine and its effects.
drate which undergo metabolism. An excessive accumulation
(Also see ATROPINE; BELLADONNA DRUGS; and DIGES-
of acetoacetic in the body results in the condition called keto-
TION AND ABSORPTION.)
sis.
(Also see ACID-BASE BALANCE.) ACETYLCOENZYME A
ACETOBACTER Acetobacteriaceae A key substance formed during the metabolism of carbo-
hydrates, fats, and proteins. It plays important roles in (1)
A genus of bacteria used aerobically (with air) to convert the production of energy, carbon dioxide, and water from
alcohol to acetic acid. An acetobacter, Acetobacter pasteur- the intermediate products of metabolism; and (2) the syn-
ianus is used in the making of vinegar. thesis of fatty acids, ketone bodies, acetylcholine, choles-
©1995 CRC Press LLC
terol, and related compounds. ditions. Sometimes, these stones dissolve in acid. Therefore,
(Also see METABOLISM.) acid-ash diets are used to keep the urine acid.
(Also see ACID FOODS AND ALKALINE FOODS; and
ACHALASIA DISEASES.)
A malfunctioning of the muscular coat around the esopha-
gus. There is less than the normal amount of peristalsis and ACID-BASE BALANCE
the lower sphincter fails to relax. Hence, solid food tends to
remain in the esophagus because it cannot pass into the An acid is a chemical that can release hydrogen ions,
stomach. The condition may be corrected by surgery, or by whereas a base, or alkali, is a chemical that can accept
stretching the lower sphincter with a dilator. hydrogen ions. For the pH, hydrogen ion concentration, of
(Also see DIGESTION AND ABSORPTION.) extracellular fluid to remain normal, a balance between acids
and bases must be maintained. This equilibrium is known as
ACH INDEX (ARM, CHEST, HIP INDEX) the acid-base balance; it refers to the hydrogen ion concen-
tration in the body fluids. When the hydrogen ion concentra-
This refers to the arm girth, chest diameter, and hip width. It
tion is high, the fluids are acidic — the condition is acidosis;
is sometimes used as a method of assessing the state of nutri-
when the hydrogen ion concentration is low, the fluids are
tion.
basic — the condition is alkalosis. Since the chemical reac-
tions of the cells depend very greatly on the hydrogen ion
ACHLORHYDRIA
concentration, the acid-base balance must be regulated very
A condition in which there is a lack of hydrochloric acid in precisely.
the gastric juices. The degree of acidity is expressed in terms of pH. A pH of 7
(Also see AUTOIMMUNITY; DIGESTION AND ABSORP- is the neutral point between an acid and an alkaline (base).
TION; and DISEASES.) Substances with a lower pH than 7 are acid, while substances
with a pH above 7 are alkaline. The normal pH of the extra-
ACHOLIC cellular fluids of the body is 7.4, with a range of 7.35 to 7.45.
Maintenance of the pH within this narrow range is necessary
An abnormal condition in which there is a deficiency of to sustain the life of cells. The extremes between which life is
bile. possible are 7.0 to 7.8.
(Also see DIGESTION AND ABSORPTION.)
ACHROMOTRICHIA BUFFER. In chemistry, a buffer is a mixture of acidic and
alkaline components, which protects a solution against wide
A lack of pigment or graying of the hair. It occurs in rats as a variations in the pH, even when strong bases or acids are
result of pantothenic acid deficiency. The discovery of this added to it. A solution containing such a protective mixture is
condition led to the designation of pantothenic acid as the called a buffer solution. A buffer protects the acid-base bal-
antigray hair vitamin. However, there is no evidence that it ance of a solution by rapidly offsetting changes in its ionized
prevents the graying of hair in people. hydrogen concentration. It works by protecting against either
(Also see PANTOTHENIC ACID.) added acid or base.
ACID
ACID-FORMING AND BASE-FORMING FOODS.
A substance which has a pH of 6.9 or lower and is capable
The potential acidity or alkalinity of the foods ingested cov-
of turning litmus indicators red. It is responsible for the sour
ers a wide range and depends on the minerals present. On
taste of foods such as lemons, pickles, tomatoes, vinegar, etc.
combustion, certain foods, such as most vegetables and fruits,
Many acids occur naturally in foods, while others are added
leave an ash in which the basic elements (sodium, potassium,
for flavoring, or to inhibit the growth of certain microorgan-
calcium, and magnesium) predominate; hence, they are
isms associated with food spoilage. Acids also occur naturally
known as base-forming foods. Other foods, such as cereals,
in the body, such as the hydrochloric acid of the stomach.
meat, and fish, leave an ash in which the acid-forming ele-
(Also see ACID-BASE BALANCE; ACID FOODS AND
ments (chlorine, phosphorus, and sulfur) predominate; these
ALKALINE FOODS; ADDITIVES; and PRESERVATIVES.)
are known as acid-forming foods. Although sulfur is present
in foods mainly in neutral form in the sulfur-containing amino
ACID-ASH RESIDUE
acids (methionine, cystine, cysteine), it is oxidized in the
A mineral residue which is left after (1) the other nutrients in body to sulfuric acid; hence, it is an acid-forming mineral.
a food have been metabolized or (2) a food has been burned Therefore, foods containing a large amount of protein are
to an ash in a laboratory. Ashes of foods give an acid reaction, generally acid-forming. Contrary to popular belief, citrus
when the predominant chemical elements are chlorine, phos- fruits are not acid-forming. They do contain citric acid and
phorus or sulfur, because these elements generally form acid potassium citrate, but the citrate radicals are completely
acids. Foods which are most likely to have an acid residue are metabolized in the body, leaving only potassium. Thus, many
breads and cereal products, eggs, fish, meats, and poultry. acid fruits are really base forming foods.
Milk has an alkaline residue. (Also see ACID FOODS AND ALKALINE FOODS.)
(Also see ACID FOODS AND ALKALINE FOODS.)
ACID-ASH RESIDUE DIETS REGULATION OF ACID-BASE BALANCE. Regula-
tion of the acid-base balance refers to the control of the
These diets leave an acid residue in the body because they hydrogen ion concentration in the body fluids. It is very
contain foods rich in chlorine, phosphorus and/or sulfur — important that the pH of body fluids be maintained within
such as eggs, meat, fish, poultry, bread, and cereal products. the narrow, slightly alkaline range of 7.35 and 7.45, because
They are often prescribed for patients with kidney stones variance from this range leads to disruption of normal body
(calculi) that are believed to be formed under alkaline con- processes and activity. The acid-base balance is regulated
©1995 CRC Press LLC
by chemical buffers, by the lungs (respiratory), and by the ity of the respiratory center affords an automatic mechanism
kidneys (renal), as follows: for maintaining a fairly constant pH of the body fluids. That is,
1. Chemical Buffers. All of the body fluids contain acid- an increase in hydrogen ion concentration increases the rate
base buffers. These are chemicals that can combine readily of ventilation, which in turn removes carbonic acid from the
with any acid or base in such a way that they keep the acid fluids. Loss of the carbonic acid decreases the hydrogen ion
or base from changing the pH of the fluids greatly. The concentration back toward normal. Conversely, diminished
three most important chemical buffers are the bicarbonate hydrogen ion concentration depresses the ventilation, and the
buffer, phosphate buffers, and protein buffers. hydrogen ion concentration rises back toward normal. This
a. Bicarbonate Buffer. This buffer, which is present in all respiratory mechanism for regulating acid-base balance
body fluids, is a mixture of carbonic acid (H CO ) and reacts almost immediately when the extracellular fluids
2 3
bicarbonate ion (HCO -). When a strong acid is added to become either too acidic or too basic. Thus, acidosis greatly
3
increases both the depth and rate of respiration, while alkalo-
this mixture, it combines immediately with the bicarbonate
sis lessens the depth and rate of respiration. This respiratory
ion to form carbonic acid—an extremely weak acid. Thus,
mechanism is so effective in regulating the acid-base balance
this buffer system changes a strong acid to a weak acid and
that it usually returns the pH of the body fluids to normal
keeps the fluids from becoming strongly acid. However,
within a few minutes after an acid or alkali has been adminis-
when a strong base is added to this mixture, the base
tered.
immediately combines with the carbonic acid to form
water and neutral bicarbonate salt.
3. Kidneys (renal). In addition to carbonic acid, a num-
Loss of the weak acid and the addition of the neutral salt ber of other acids are continually being formed by the met-
scarcely affect the hydrogen ion concentration in the body abolic process of the cells, including phosphoric, sulfuric,
fluids. Thus, the carbonic acid-bicarbonate buffer system pro- uric, and keto acids. On entering the extracellular fluids,
tects the body fluids from becoming either too acidic or too all of these can cause acidosis. Normally, the kidneys rid
basic. the body of these excess acids as rapidly as they are
b. Phosphate buffers. These chemical buffers are espe- formed, preventing an excessive build-up of hydrogen ions.
cially important for maintaining normal hydrogen ion con- Occasionally, too many basic compounds enter the body
centration in the intracellular fluids, because their fluids, rather than too many acidic compounds. This may
concentration inside the cells is many times as great as the occur when basic compounds are injected intravenously or
concentration of the bicarbonate buffer. when large quantities of alkaline food or drugs are consumed.
c. Protein buffers. Like phosphate buffers, protein buff- The kidneys regulate acid-base balance by (a) excreting
ers, including hemoglobin, are especially important within hydrogen ions into the urine when the extracellular fluids are
the cells. too acidic, and (b) excreting basic substances, particularly
sodium bicarbonate, into the urine when the extracellular flu-
In essence, the chemical buffers of the body fluids are the
ids become too alkaline.
first line of defense against changes in hydrogen ion concen-
The kidneys also conserve base by eliminating extra hydro-
tration, for any acid or base added to the fluids immediately
gen ions through the production and excretion of ammonia
reacts with these buffers to prevent marked changes in the
(NH):
acid-base balance. 4
2. Lungs (respiratory). Carbon dioxide combines with NH3 (from deamination + H+ NH4 of amino acids)
water and electrolytes in the extracellular fluid to form car-
bonic acid in accordance with the following reaction: If the normal amounts of buffers are present in the blood,
and if the lungs and kidneys are normal, one can recover
promptly from the effects of severe muscular exercise, intake
of acid or base, unbalanced diets (so far as acids and bases
Ultimately, the lungs control the body's supply of car-
are concerned), short periods of starvation, short bouts of
bonic acid. This is so because, normally, respiration
vomiting, and other adverse conditions. But there are limits to
removes carbon dioxide at the same rate that it is formed
the adjustments that the body can make; if the capacity is
by all cells of the body as one of the end products of
exceeded, the pH changes and the body cells are prevented
metabolism. However, if respiration decreases below nor-
from performing their functions normally.
mal, carbon dioxide will not be excreted normally; instead,
it will accumulate in the body fluids, causing an increase in
the concentration of carbonic acid. As a result, the hydro-
ABNORMALITIES OF ACID-BASE BALANCE.
gen ion concentration rises. On the other hand, if the respi-
ration rate rises above normal, the opposite effect occurs; Many disorders of the respiratory system, the kidneys, or
carbon dioxide is blown off at a more rapid rate than it is the metabolic system for forming acids and bases can cause
formed, thereby decreasing the carbon dioxide and car- serious derangement of the acid-base balance. Some of the
bonic acid concentrations. It is noteworthy that complete effects of these conditions, compared with the normal pH of
lack of breathing for a minute will reduce the pH of the the blood of 7.4, are shown in Fig. A-1; and a brief discussion
extracellular fluid from the normal of 7.4 down to about of each condition follows:
7.1, while over-breathing can increase it to about 7.7 in a Acidosis generally causes depressed mental activity, and, if
minute. Thus, the acid-base balance of the body can be unchecked, it may culminate in coma and death. Usually the
changed greatly by under- or over-ventilation of the lungs. afflicted person will pass into a coma when the pH of the
In the preceding paragraph, the effect of changing the rate extracellular fluid falls below 6.9.
of breathing on the acid-base balance is detailed. In this para- Alkalosis causes overexcitability, resulting in excessive ini-
graph, the opposite effect of the acid-base balance on respira- tiation of impulses, muscle contraction, and even convul-
tion is discussed. A high hydrogen ion concentration sions.
stimulates the respiratory center in the medulla of the brain, In acidosis, the ionized hydrogen concentration is above
greatly enhancing the rate of ventilation. Conversely, a low normal. In alkalosis, ionized hydrogen concentration is
hydrogen ion concentration depresses the rate of ventilation. below normal. Either of these abnormal states initiates
So, the effect of the hydrogen ion concentration on the activ- compensatory responses of the chemical buffers, lungs, and
©1995 CRC Press LLC
kidneys, which cause body fluids to accept, to release, or to depletion, burning of body protein and fat, and finally ketosis;
excrete ionized hydrogen. Increases and decreases in ion- severe diarrhea, induced because large amounts of bicarbon-
ized hydrogen concentration are changed so that the pH is ate (HCO) and sodium (Na) are swept away with the intesti-
3
not significantly changed from its normal range of 7.35 to nal contents; and chronic or acute kidney disease, as the
7.45. Failure of either the lungs or the kidneys to carry out kidneys become unable to cope with excess ionized hydro-
this function results in acidosis or alkalosis. If the failure is gen concentrations.
largely related to the lungs (respiratory), it is called respira- Examples of metabolic alkalosis include: initial vomiting,
tory acidosis or respiratory alkalosis. If the failure is mainly resulting in loss of ionized hydrogen and chlorine; potas-
related to the kidneys, it is called metabolic acidosis or sium depletion (caused by insufficient potassium intake, gas-
metabolic alkalosis. trointestinal loss of potassium, or ACTH therapy), inducing
Examples of diseases that affect the lungs and contribute to alkalosis as ionized hydrogen and sodium move into the
the development of respiratory acidosis are: pneumonia, cells to replace the lost potassium; and excess intake of
emphysema, asthma, pulmonary edema, barbiturate poison- alkali powders or sodium bicarbonate, as in long-term ulcer
ing, morphine poisoning, and congestive heart failure. Com- therapy.
mon causes of respiratory alkalosis are: extreme emotion, In all cases of acid-base imbalance, three basic rules
hysteria, or anxiety (causing hyperventilation); labored should be followed: (1) rely on a medical doctor for diag-
breathing in response to hot weather, high altitude, or fever nosis and prescribed treatment, (2) treat the primary cause
(causing hyperpnea); excessive breathing forced upon! a of the acidosis or alkalosis, and (3) make every effort to aid
patient by a poorly adjusted mechanical respirator; or over- the various compensatory responses of the lungs and kid-
stimulation of the respiratory center in the brain, which may neys.
be brought about by aspirin, poisoning, meningitis, or
encephalitis. ACID-BASE REACTION OF FOODS
This refers to the potential acidity or alkalinity of food,
which depends upon the reaction they yield after being
broken down (metabolized) in the body, thus releasing
their mineral elements. These minerals function in main-
taining the acid-base balance in the body. Acid-forming
elements are chlorine, phosphorus, and sulfur, while base
(alkaline)- forming elements are calcium, sodium, potas-
sium, and magnesium. Foods can be classified as acid
foods, alkaline (basic) foods, or neutral foods according to
their mineral content.
(Also see ACID-BASE BALANCE; ACID FOODS AND
ALKALINE FOODS; and WATER AND ELECTROLYTES, sec-
tion headed "Acid-Base Balance.")
ACID DETERGENT FIBER (ADF)
The fiber which is extracted from plant foods with acidic
detergent, a technique employed to determine indigestible
matter. The extract is composed of cellulose and lignin, cell-
wall substances which are not digested by man.
(Also see ANALYSIS OF FOODS; CARBOHYDRATES,
UNAVAILABLE; and FIBER.)
ACID FOODS AND ALKALINE FOODS
The metabolism of many foods results in a small amount of
mineral residue, or ash (so-called because it is similar to the
ash remaining after burning material). Only highly refined
foods, consisting chiefly of fats, sugars, or starches do not
yield an ash. The processing of such foods has resulted in the
removal of the mineral elements; the carbon, hydrogen, and
oxygen which remain are metabolized to water, carbon diox-
Fig. A-1. pH of the body fluids in various acid-base disorders compared ide, and energy.
with normal pH.
A solution of the mineral residue of a food will, upon test-
Examples of metabolic acidosis are: diabetic acidosis, ing, give an acid, alkaline (basic), or neutral reaction,
brought about because the body cannot metabolize blood depending upon the relative proportions of acid-forming
glucose properly and turns for its energy to the catabolism of elements (chlorine, phosphorus, and sulfur) and of alkali-
protein and fat; starvation, when the body turns to its own forming elements (potassium, sodium, calcium, and mag-
stores of protein and fat to supply its needs; greatly acceler- nesium). The type of reaction of the food ash in water is
ated metabolism, such as thyrotoxicosis, resulting in the important because it gives an indication of the contribution
depletion of carbohydrate stores and the burning of protein of the food to the acidity, alkalinity, or neutrality of the body
stores, followed by ketosis; gastrointestinal problems, such as fluids, and, ultimately, to the urine. The kidneys help to
may be caused by prolonged vomiting and the inability to maintain the neutrality of the body fluids by excreting the
eat, resulting in decreased carbohydrate intake, glycogen excess acid or alkali in the urine.
©1995 CRC Press LLC