Caballero B. (ed.) Encyclopaedia of Food Science, Food Technology and Nutrition. Ten-Volume Set

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infected animals, but also from meat which has been

contaminated by human carriers of salmonellae

during slaughter procedures. Contamination of meat

from infected animals during slaughter is a consider-

able problem and careful ante- and postmortem

inspection combined with a satisfactory standard of

slaughter hygiene are essential to reduce the danger of

widespread contamination and subsequent dissemin-

ation of the bacteria.

Anthrax

0052 This is a highly infectious bacterial disease of animals,

quite commonly encountered in tropical countries.

Humans can acquire the disease from infected car-

casses or byproducts by handling, inhaling contamin-

ated air, or eating infected meat. Anthrax can often be

detected by proper antemortem inspection, but the

disease can be overlooked. Even an experienced in-

spector may have difficulty under certain conditions

in differentiating anthrax from other septicemic dis-

eases. For these occasions minimal laboratory facil-

ities for early on-the-spot provisional diagnosis are

essential.

0053 Once an infected anthrax carcass has been removed

unnoticed from the abattoir the disease can spread

rapidly. The anthrax bacillus forms resistant bacterial

spores which can remain viable in the soil and else-

where for very long periods. Care should be taken to

remove a suspected carcass from the abattoir floor. To

avoid further contamination the premises should be

disinfected with a 2% caustic soda solution. Car-

casses infected with anthrax should be destroyed

completely, if possible by burning. If buried, the pit

should be sufficiently deep to prevent the carcass

being dug up by dogs or other predators. Lime

sprinkled on the carcass before burial also helps

reduce the danger of the disease spreading.

Cysticercosis

0054 This condition is prevalent in cattle in many tropical

areas and is a particular health hazard to humans

because infected cattle and buffalo muscles contain

the cysts, which are an intermediate or developmental

stage of Taenia saginata, one of the large human

tapeworms. Cattle and buffalo grazing on pastures

contaminated with human feces containing these

tapeworm eggs can become infected. The muscular

tissue of the cattle and buffalo then become infected

with the tapeworm cysts and if humans eat

improperly cooked beef they become infected and

the cycle of development can recur.

0055 Meat inspectors usually cut into the cheek muscles

and heart muscles to check for the presence of cysts.

In Zebu-type cattle the hump is also a further useful

site for muscle incisions.

Hydatidosis

0056The importance of this disease lies in both its human

health and economic aspects. The dog is the most

important link in the biological cycle of this tape-

worm and for this reason control should be directed

at proper treatment of dogs with anthelmintics, keep-

ing them out of slaughter premises, and the proper

disposal of the viscera of all slaughter animals. The

hydatid cysts are intermediate developmental stages

of dog tapeworms. These cysts can develop not only

in large and small ruminants and swine, but also in

humans, where they may even locate themselves in

the brain. From the human infection standpoint, the

hydatid cysts in the viscera of sheep and swine are

the most dangerous as far as potential infection of

scavenging dogs is concerned, because cysts in these

animals are much more fertile than those found in

cattle and buffalo.

See also: Canning: Principles; Chilled Storage:

Principles; Curing; Dehydration; Parasites: Occurrence

and Detection; Pickling; Sterilization of Foods

Further Reading

FAO (1985) Production Year Book of the Food and Agri-

culture Organization of the United Nations. Rome:

Food and Agriculture Organization.

FAO (1988) FAO statistics of livestock population of the

countries in Asia Pacific Region. Asian Livestock 13: 94.

Hill D (1988) Slaughter methods, meat hygiene and carcass

quality. In: Cattle and Buffalo Meat Production in the

Tropics, pp. 142–149. Longman Scientific and Technical.

Mudgal VD (1987) Prospectus of buffalo as dairy animal in

India. Asian Livestock 12: 28–32.

Mudgal VD and Sharma DD (1993) Buffalo meat. In:

Encyclopaedia of Food Science, Technology and Nutri-

tion, vol. 1, pp. 521–529. London: Academic Press.

Milk

C D Khedkar, College of Dairy Technology, Warud

(Pusad), Maharashtra, India

G D Khedkar, Dr Babasaheb Ambedkar Marathwada

University, Aurangabad, Maharashtra, India

M R Patil, College of Dairy Technology, Warud (Pusad),

Maharashtra, India

S D Kalyankar, Marathwada Agricultural University,

Parbhani, Maharashtra, India

Introduction

0001Buffalo plays a pivotal role in the agricultural econ-

omy of many Asian, European, African, and Latin

BUFFALO/Milk 705

American countries. Among farm livestock buffalo is

being increasingly recognized as an animal for milk,

meat, and draft. Despite its significant contribution as

a multipurpose animal, this species has received little

of the care and attention which it rightly deserves. A

major bottleneck in the enhancement in production

potential of buffaloes has been inadequate research

and paucity of information. It is often falsely pre-

sumed that the scientific information generated on

cattle can be extrapolated to buffaloes.

Milk Production

0002 In terms of the percentage of world milk production

from buffaloes, India ranks first (65%), followed by

Pakistan (22%), China (5%), Egypt (4%), and Nepal

(2%). Various compositional and functional proper-

ties render buffalo milk (BM) eminently suitable for

the manufacture of dairy products such as ultra heat-

treated (UHT) cream, dried icecream mixes, dairy

whiteners, edible casein, and caseinates. However,

from a technological point of view, BM is often con-

sidered not an ideal fluid for the manufacture of

several types of cheeses, milk powders, evaporated

and condensed milk, and infant formulae. Due to

several biochemical differences between BM and

cows’ milk (CM), conventional processing tech-

nologies are often unsuitable and cannot be applied

directly for processing BM.

0003 Emerging research and development trends in BM

processing suggest that there is ample scope for

tailoring the technology, particularly in the de-

veloping world where buffaloes enjoy a preeminent

position in milk production. Several region-specific

traditional milk products owe their unique character-

istics to BM. The suitability of buffalo as a milk

producer is now distinctly gaining importance

throughout the world.

Comparative Appraisal of Gross

Composition of Buffalo and Cows’ Milk

0004 BM is reputed for its richness and creaminess. The

compositions of BM and CM are compared in

Table 1; BM has a higher content of fat, lactose,

casein, whey proteins, and minerals than CM. All of

the casein in BM is present in the micellar form while

in CM only 90–95% of the casein is in the micellar

state and the rest is present in serum phase. The

proportion of bovine casein which is micellar depends

on the temperature range and the gravitational force

used to sediment casein micelles. The size of the

casein micelles is bigger (110–170 nm) in BM com-

pared to CM (range 50–500 nm, mean 120–150 nm).

The voluminosity of the casein micelles in BM is

2.68–3.72 ml g

1

compared to 4.18 ml g

1

for CM

casein. Similarly, the solvation (hydration of casein

micelles) of BM is lower (2.60–2.90 g water g

1

casein compared to 3.48 g water g

1

of casein from

CM). The opacity of BM casein micelles is three times

higher than CM casein. BM casein micelles contain

higher levels of calcium and magnesium but lower

levels of sialic acid and hexose. The lactoferrin con-

tent of BM is 32 mg 10 ml

1

compared to 15 mg

100 ml

1

of CM. No genetic polymorphism is ex-

hibited either by the caseins or whey proteins in BM.

Milk Lipids

0005BM fat contains higher proportions of high melting

triglycerides (9–12%) than CM (5–6%) and as a

result it is more solid. Similarly, the proportion of

butyric acid-containing triglycerides is higher (50%)

in BM than in CM (37%). As a consequence of the

higher proportion of butyric acid-containing trigly-

cerides, the emulsifying capacity of BM fat is superior

to CM fat. Fat globules are bigger (4.15–4.6 mm) in

BM than in CM (3.36–4.15 mm). These are rendered

chargeless at much higher pH (4.5–4.6) in BM com-

pared to CM (pH 4.3). BM fat contains less (0.22%)

free fatty acids than CM (0.33%). The concentration

of unsaponifiable matter (392–398 mg 100 ml

1

)

is also lower in BM than in CM (414–450 mg

100 ml

1

). Similarly, the phospholipid content of

BM is also less (21 mg 100 ml

1

compared to

37.37 mg 100 ml

1

. The total and free cholesterol

content is 275 mg and 210 mg, respectively, per

tbl0001Table 1 Concentration of major constituents in buffalo and

cows’ milk

Constituents Concentration (%)

Buffalo milk Cows’milk

Water 83.18 85.5

Total solids (TS) 16.82 13.5

Solids not fat (SNF) 10.01 9.11

Fat 6.71 4.39

Proteins 4.52 3.3

Lactose 4.45 4.44

Total ash 0.80 0.73

Calcium 0.18 0.12

Magnesium 0.02 0.01

Sodium 0.05 0.05

Potassium 0.11 0.15

Phosphorus 0.10 0.10

Citrate 0.18 0.18

Chloride 0.07 0.1

Ca/P ratio 1.8 1.2

Adapted from Sindhu J (1999) Physico-chemical profiles of cow and buffalo

milk in relation to milk processing. In: Advances in Processing and

Preservation of Milk: A Compendium of Short Term Course Notes, pp. 97–103.

Karnal, India: National Dairy Research Institute.

706 BUFFALO/Milk

100 g of BM ghee, which is much less than corres-

ponding values of 330 mg, and 280 mg 100 g

1

in CM

ghee. On the other hand, the esterified cholesterol

of BM is much higher (64 mg 100 g

1

) CM than

(48 mg 100 g

1

Milk Salts

0006 The concentration of calcium and magnesium is

about 1.5 times higher in BM than in CM. On the

other hand the concentration of sodium, potassium,

and chloride is lower than in CM. The content of

colloidal calcium and magnesium (160 and 9 mg,

respectively 100 ml

1

) in BM is much higher than

in CM (80 and 3 mg, respectively, 100 ml

1

). Only

about 20% of calcium and 55% of magnesium in BM

is present in a dissolved state compared to 33% and

75% respectively in CM. The Ca/P ratio is much

higher in BM (1.8) than in CM (1.2).

Vitamins

0007 BM is a rich source of most water-soluble and fat-

soluble vitamins. The average concentrations of vita-

mins in milk of buffalo, Indian, and western cow are

summarized in Table 2; vitamin A content is higher in

BM (340 IU kg

1

) than in CM (230 IU kg

1

). How-

ever, due to the absence of carotenoids and the high

fat content in BM, its total vitamin A potency per unit

weight of fat is less than CM. Similarly, the toco-

pherol (vitamin E) content of BM is slightly higher

(334 ng kg

1

milk) than 312 ng kg

1

CM. However,

due to the higher fat content in BM, its fat is poor in

tocopherol (26 ng g

1

fat compared to 35 ng g

1

fat in

CM).

Pigments in Buffalo Milk

0008 Biliverdin IX alpha, a latent blue-green pigment,

occurs in fresh BM. This pigment is absent from CM

and is considered to be an important characteristic of

BM. The average concentration of biliverdin in skim

milk of Murrah and Surati buffaloes is 51.8 and 65 mg

100 ml

1

, respectively. The concentration of this pig-

ment in BM varies significantly at different stages of

lactation and lactation number. Biliverdin was pri-

marily associated with a-, b-, and k-caseins and the

proteose-peptone fraction of BM. Biliverdin is con-

verted to bilirubin on storage and souring of BM. This

pigment binds to BM lipids and imparts the charac-

teristic greenish-yellow appearance to BM fat and

butter prepared by the traditional fermentation pro-

cess.

Other Constituents

0009BM is rich in taurine (6 mol l

1

), compared to 4.0 mol

1

in CM. In contrast, the concentration of urea in

BM, 17–22 mg 100 ml

1

is much lower than the level

in CM (37–40 mg 100 ml

1

). The levels of lipase and

alkaline phosphatase are lower in BM than in CM.

However, free amino acids are present at a higher

concentration (0.44%) in BM than in CM (0.15%).

Differences in Physicochemical

Properties of Cow and Buffalo Milk

0010Precise and indepth information on the physicochem-

ical and functional attributes of milk is an essential

prerequisite for automated industrial processing.

Most of the prevalent processing technologies appar-

ently originated in the western world, where CM

and milk products predominate. Therefore, process-

ing strategies were essentially based on knowledge of

the chemistry and functionality of CM. Species-

related differences in milk composition have become

the subject of topical interest, as processing of milk

from species other than cow is being adopted by the

dairy industry in several countries. With the emer-

gance of buffaloes as a predominant milk species,

particularly in countries of Asia, Africa, and Latin

America, coupled with rapid dairy development,

tbl0002 Table 2 Average concentration of some vitamins in milk of Buffalo, Indian, and western cow

Vitamins Concentration inmilk

Buffalo (Bubalus bubalis) Zebu (Bos indicus) Western cow (Bos taurus)

Vitamin A (IU ml

1

) 340 230 136–157

Thiamin (mgml

1

) 0.2–0.5 0.2 0.2–0.8

Riboflavin (mgml

1

) 1.59 2.33 1.7

Pyridoxine (mgml

1

) 3.25 2.6–3.0

Ascorbic acid (mg 100 g

1

) 6.72 1.94 1.65–2.75

Tocopherol (mgg

1

) 334.2 312.2

Adapted from Sahais (1996) Compositional profile of buffalo milk. In: Buffalo Milk: Chemistry and Processing Technology, pp. 20–57. Karnal, India: SI

Publishers.

BUFFALO/Milk 707

efforts have been made to develop and adopt appro-

priate technologies for BM processing. It becomes

essential to understand the unique physicochemical

and functional properties of BM to overcome the

various challenges encountered during its processing.

BM has higher specific gravity, viscosity, curd tension,

pH, oxidation reduction potential (E

), thermal con-

ductivity, and thermal expansion than CM but its

heat capacity and rennet stability are lower than

CM. In the fluid state, BM is as stable as CM to

various physicochemical factors. In contrast, the

heat-stability of concentrated milk product is signifi-

cantly lower than BM. Owing to differences in phys-

ical properties, milk from the two species behave

differently when processed for manufacturing of

the products. A comparison of the physicochemical

properties of BM and CM is given in Table 3.

Comparison Between the Quality of Dairy

Products from Cows’ and Buffalo Milk

Edible Casein and Caseinates

0011 Due to the higher content of casein in the form of

larger micelles and the presence of all of the casein in

the micellar state, it is easier to manufacture edible

casein and caseinates from BM. The yield of these

products is also higher from BM due to lower losses

in the whey because of greater size and low hydration

of the micelles.

Coffee and Tea Whiteners

0012 Due to higher protein, fat, and calcium content in BM,

the yield of whitener from BM is higher. The product

is superior due to higher whitening capacity when

made from BM. The larger size and greater opacity

of casein micelles from BM may be responsible for a

better-quality product. The higher emulsifying cap-

acity of BM fat may also be responsible for the better

dispersion of whitener used in coffee or tea.

Icecream

0013Buffalo milk is considered as a better source of fat for

icecream due to higher emulsifying capacity. Further,

BM ingredients produce better body and texture in

icecream.

Infant and Health Foods

0014Better absorption of fat due to higher emulsifying

capacity, better absorption of calcium due to higher

concentration of calcium, magnesium, lactoferrin,

free amino acids, esterified cholesterol and taurine

and lower concentration of sodium, potassium, chlor-

ide, urea, and free and total cholesterol in BM com-

pared to CM is beneficial for human nutrition. These

attributes make BM superior to CM as an ingredient

for infant and health foods provided its curd tension

is reduced to improve digestibility.

Certain Varieties of Cheese

0015Certain varieties of cheese, like Mozzarella and white

pickled Domiati cheese, are superior in quality when

made from BM. The manufacture of Domiati cheese

is easier from BM as it is easier to handle the curd to

as it is firmer and the yield is higher.

Yogurt

0016Buffalo milk is better suited for the manufacture of

yogurt as its manufacture is easier and there is no

need for prior concentration or the addition of dried

milk due to higher total solids in fat.

tbl0003 Table 3 Physicochemical properties of buffalo and cows’ milk

Properties Buffalo milk Cows’milk

Specific gravity (20



C) 1.03 1.03

Viscosity (in cP at 20



C) 2.25 1.45

Curd tension (in g) 32.85 28.54

Surface tension (dyn cm

1

at 20



C) 45.5 42.5

Freezing point (



C) 0.55 0.53

pH (at 20



C) 6.7 6.6

Acidity as % lactic acid 0.16 0.15

Redox potential (volts) 0.31 0.26

Electrical conductance (m ohm) 43.22–6.77 4.0–5.50

Thermal conductance (kcal h

1



Cat37



C) 0.57 0.46

Heat capacity (cal g

1



Cat30



C) 0.83 0.93–0.95

Heat-stability (in min at 130



C) 32.28 32.0

Adapted from Sindhu JS (1999) Physico-chemical properties of cow and buffalo milk in relation to milk processing. In: Advances in Processing and

Preservation of Milk: A Compendium of Short Term Course Notes, pp. 97–103. Karnal, India: National Dairy Research Institute.

708 BUFFALO/Milk

Problems Associated with Buffalo Milk

Cheese

0017 Cheddar cheese is manufactured mainly from CM in

major cheese-producing countries. However, in India

the major share of milk production is from buffaloes.

The adaptation of well-known technology for the

production of various products from BM posed

many problems, primarily because of its qualitative

and quantitative differences. CM, in general, is con-

sidered to be the most suitable raw material for

cheese. The main problems encountered in the manu-

facture of hard-type cheese from BM have been faster

renneting, lower retention of moisture, slower lipoly-

sis and proteolysis, and poor flavor, body, and texture

development. BM cheese is criticized for its higher fat

content and hard, rubbery, and dry body and texture.

0018 The defects in BM Cheddar cheese are mainly

attributed to the physicochemical and compositional

characteristics of milk. The high buffering capacity of

BM due to its higher calcium phosphate and casein

content is the cause of a slower development of acid-

ity. Faster renneting time may be attributed to its

higher colloidal content (about 160 mg 100 ml

1

compared to only 8 mg 100 ml

1

in CM). The lower

retention of moisture in the curd may be the result of

low solvation (hydration) of its calcium compared to

CM casein. Hard, rubbery, and dry body may be due

to the high curd tension which, in turn, is the result of

higher content of casein with bigger size of the mi-

celle, high content of calcium and magnesium, more

so in the colloidal state, large proportion of solid fat

with bigger size of globules, and low voluminosity

and solvation of casein micelles compared to the

same in CM. The slower rate of proteolysis and lipo-

lysis is the cause of the higher curd tension of BM.

Technology for Manufacture of Buffalo

Milk Cheese

0019 In view of the above-mentioned problems associated

with the manufacture of BM cheese, research was

initiated in the area of cheese in the early 1960s at

the National Dairy Research Institute, Karnal, India.

Since a major share of milk production is from buffa-

loes and BM is known to be unsuitable for cheese

production, attention was given to this raw material.

Cheddar cheese, the most common variety made in

India, does not develop proper flavor, body, and tex-

ture when it is made from BM. The main problem is

the faster rate of syneresis which results in lower

moisture content in finished cheese. This in turn ad-

versely affects the three most important biochemical

reactions, i.e., glycolysis, proteolysis, and lipolysis,

which constitute the major activities in cheese flavor

development. In order to overcome this problem,

attempts should be made to develop a manufacturing

technique which would insure greater retention

of moisture and accelerated rate of glycolysis, prote-

olysis, and lipolysis. A presalting method has been

developed which envisages the addition of 1% salt

to the cheese milk. This method resulted in the

best product. However, addition of salt to the

milk makes the whey unsuitable for use in food

products.

See also: Casein and Caseinates: Methods of

Manufacture; Cheeses: Types of Cheese; Ice Cream:

Properties and Analysis; Milk: Liquid Milk for the

Consumer; Analysis; Dietary Importance; Yogurt: The

Product and its Manufacture

Further Reading

Kanawjia SK (1998) Modified practices for Cheddar cheese

making from buffalo milk. In: Advances in Cheese and

Fermented Milk Products: A Compendium of Short

Term Course Notes, pp. 54–59. Karnal, India: National

Dairy Research Institute.

Sahai D (1996) Compositional profile of buffalo milk. In:

Buffalo Milk: Chemistry and Processing Technology,

pp. 20–57. Karnal, India: SI Publishers.

Sindhu JS (1999) Physico-chemical properties of cow and

buffalo milk in relation to milk processing. In: Advances

in Processing and Preservation of Milk: A Compendium

of Short Term Course Notes, pp. 97–103. Karnal, India:

National Dairy Research Institute.

BUFFALO/Milk 709

BULIMIA NERVOSA

D S Goldbloom and P E Garfinkel, Centre for

Addiction and Mental Health, Toronto, Ontario, Canada

Definition

0001 The symptom of bulimia refers specifically to binge

eating, i.e., the consumption of a large amount of

food in a discrete period of time with a sense of loss

of control. As an isolated symptom, bulimia may

occur in a number of normative and pathological

states. Isolated episodes of pleasurable binge eating

among adolescents and young adults are relatively

common. Pathological binge eating may occur in

medical conditions such as Prader–Willi syndrome

or idiopathic Parkinson’s disease.

0002 The term bulimia nervosa (BN), however, refers to

a distinct psychiatric disorder of eating behavior

which includes but is not limited to episodes of

binge eating. It is also characterized by distinct psy-

chological preoccupations regarding fears of becom-

ing fat and self-esteem yoked to body weight that

parallel concerns in its companion disorder anorexia

nervosa (AN). Accompanying the episodes of binge

eating, and fueled by the fears of obesity, are feelings

of loss of personal control and efforts to counteract

the effects of ingested calories through a variety of

purgative techniques.

0003 Unlike the long-recognized AN, BN was formally

characterized as an autonomous disorder as recently

as 1979; the formal diagnostic criteria for BN as

described by the American Psychiatric Association

in 1994 are:

A. recurrent episodes of binge eating. An episode of

binge eating is characterized by both of the

following:

0005 eating, in a discrete period of time (e.g., within

any 2-h period), an amount of food that is

definitely larger than most people would eat

in a similar time and under similar circum-

stances

0006 a sense of lack of control over eating during the

episode (e.g., a feeling that one cannot stop

eating or control what or how much one is

eating)

0007 recurrent inappropriate compensatory behavior

in order to prevent weight gain, such as self-

induced vomiting; misuse of laxatives, diuretics,

enemas, or other medications; fasting; or exces-

sive exercise

0008the binge eating and inappropriate compensatory

behaviors occur, on average, at least twice a week

for 3 months

0009self-evaluation is unduly influenced by body

shape and weight

0010the disturbance does not occur exclusively during

episodes of anorexia nervosa.

0011There are two subtypes:

0012Purging type: during the current episode of BN,

the person has regularly engaged in episodes of

self-induced vomiting or the misuse of laxatives,

diuretics, or enemas.

0013Nonpurging type: during the current episode of

BN, the person has used other inappropriate com-

pensatory behaviors, such as fasting or excessive

exercise, but has not regularly engaged in self-

induced vomiting or the misuse of laxatives, diur-

etics, or enemas.

Prevalence

0014BN is largely but not exclusively a disorder of

females, typically between the ages of 16 and 40.

The existence of a frequency criterion for binge eating

has on the one hand reduced estimates of the preva-

lence of this disorder since its initial description; on

the other hand, evidence exists that this frequency

criterion is highly arbitrary and does not capture the

full spectrum of the disorder. Approximately 1% of

western adolescent and young adult females meet

diagnostic criteria for BN.

Etiology and Groups at Risk

0015The etiology of BN is unknown; physiological, psy-

chological, and cultural cues have been invoked in its

pathogenesis and risk factors in these three domains

have been identified. The commonest acute precipi-

tant of binge eating per se is food restriction, whether

experimental or self-imposed, as in dieting or AN.

This may result from adaptive physiological signals

in the hypothalamus to ingest calories. At the same

time, the cognitive consequences of having eaten

when trying to abstain from food may provoke a

transient relaxation of rules about food that results

in a binge-eating episode. Finally, the abundant and

frequently instant availability of food in western

society may facilitate impulses to binge eat.

0016At the level of the individual, risk factors

include dieting behavior and weight preoccupation,

710 BULIMIA NERVOSA

particularly in the context of AN; up to 50% of AN

patients also exhibit bulimic behaviors. Premorbid

obesity is a risk factor in the sense that these individ-

uals are likely to be dieting and experiencing the

prominent negative social attitudes to obesity. Impul-

sivity – as manifested by substance abuse, recurrent

self-harm behavior, intense and unstable interper-

sonal relationships, and an inability to tolerate

mood states such as depression and boredom – may

be an independent risk factor. This cluster of

symptoms is often labeled borderline personality

disorder.

0017 At the familial level, psychiatric disorders such as

depression, substance abuse, eating disorders, and

antisocial behavior are overrepresented compared to

control populations. It has been argued that BN may

represent the cultural shaping of an underlying famil-

ial vulnerability to psychiatric disturbance. As with

AN, families of individuals with BN may place undue

emphasis on the importance of thinness.

0018 At the level of society, the emergence of BN as an

autonomous disorder in the latter third of the 20th

century parallels the increased emphasis on thinness,

dieting, and dieting disguised as thinness, as well as

the mushrooming of technology that allows more

widespread promulgation of social values. Many

women with BN have ‘failed’ to achieve the weight

loss requisite for a diagnosis of AN but share a set of

beliefs and values commonly seen in AN. For others,

BN represents only one expression of impulsive

dyscontrol.

Psychopathology

0019 A morbid fear of fatness and a self-appraisal based

largely on body weight and shape are the overriding

psychological preoccupations characteristic of BN.

Psychometric assessment of eating and related

attitudes parallels the findings obtained in AN. It is

important to recognize that in BN the act of binge

eating seldom occurs in response to normative hunger.

The extent to which it represents a physiological re-

sponse to food deprivation usually reflects intensive

dietary restriction for the purpose of weight loss.

However, the subjective perception of binge eating

falls typically into two categories: counterregulation

and distraction. Counterregulation refers to the phe-

nomenon whereby individuals who pursue dietary

restraint find they have violated their self-imposed

limits; their response is one of resignation to loss of

control which then triggers binge eating. In the case

of BN, this permission to binge eat is facilitated and

perpetuated by the availability of purging behaviors.

Distraction refers to the role of binge eating in

escaping from or quelling unpleasant or intolerable

psychological states, such as depression, anger, bore-

dom, or conflict; indeed, some individuals describe

their eating binges as automatic states where they

dissociate, losing touch with all feelings. Street drug

and alcohol misuse as well as nonlethal self-injurious

behavior may serve a similar function.

Clinical Features

0020As with AN, the commonest precipitant of BN is

dieting behavior. However, BN may occur without

the emaciation characteristic of AN. This may be

especially true where women have been premorbidly

overweight. Women with BN who have never had AN

still experience up to a 30% fluctuation in adult body

weight, compared to the 10% fluctuation among

women without an eating disorder. Food that is usu-

ally avoided or assigned a negative moral value inevit-

ably becomes food consumed during eating binges

where dietary restraint is abandoned.

0021BN is typically a secretive behavior. Eating binges

often occur in the evening after a day of caloric re-

striction and/or psychological stressors. Individuals

may consume between 3000 and 6000 calories in an

hour or less, and they describe their eating as rapid,

often without savoring the taste, and with a sense of

loss of control and inability to stop. Macronutrient

analysis of binge food indicates a high quantity of

carbohydrate, although perceived high-carbohydrate

foods often have a significant fat content as well. A

loss of the normal sense of satiety is evident from both

subjective ratings and objective measures of the quan-

tity of food consumed. Ironically, the aftermath of a

binge-eating episode is often heightened dysphoria,

weight concern and self-loathing, which then precipi-

tate purging behavior.

0022The commonest form of purgation is self-induced

vomiting, with individuals using a finger, toothbrush,

or pen to stimulate an oropharyngeal vomiting reflex.

The commonly available emetic, ipecac, has also been

used for this purpose with catastrophic results: ipecac

contains emetine, which is directly toxic to cardiac

muscle. Other methods of counteracting the effects of

ingested calories include laxative, diuretic, and diet

pill abuse. These lead to a variety of physiological and

psychological complications, including low serum

and intracellular potassium levels from losses through

vomiting and diuresis; this may precipitate cardiac

arrhythmias. An associated state of metabolic alka-

losis results from chloride losses through vomiting.

Alternating diarrhea and constipation may result from

laxative abuse. Diet pills are typically amfetamine-

like psychostimulants that not only suppress hunger

but also produce anxiety, insomnia, irritability, and

dependence. Less obvious forms of purgation include

BULIMIA NERVOSA 711

intensive exercise for the primary purpose of weight

loss and severe dietary restriction after binges; this

latter feature serves to perpetuate the disorder.

0023 There are few physical characteristics of BN that

facilitate its diagnosis. However, two potential signs

of the disorder are hypertrophy of the parotid saliv-

ary glands (likely secondary to overstimulation) and

calluses or erosions on the dorsum of the hand

(caused by friction against the incisor teeth while

inducing vomiting). The acid content of the vomitus

has an erosive effect on dental enamel and may pro-

mote gum recession, leading at times to an initial

diagnosis of BN by dentists. Feelings of depression

and anxiety are common in BN; indeed, these women

and their families are at higher than normal lifetime

risk for the development of autonomous mood and

anxiety disorders. However, when these symptoms

coexist with BN, it is often difficult to separate them

from other sequelae of the eating disorder.

0024 Because BN is a disorder that generates secrecy,

isolation, and shame, affected individuals may wait

months or even years prior to seeking treatment. This

contributes to the chronicity of the disorder.

Diagnosis

0025 The diagnostic criteria of the American Psychiatric

Association listed above reflect the confluence of be-

havioral and psychological features characteristic of

BN. Earlier definitions of this disorder were less re-

strictive and included a wider range of eating disturb-

ance without regard to binge-eating frequency or

weight and shape concerns. This led to epidemi-

ological overdiagnosis without regard to clinical se-

verity. However, problems remain with respect to the

definition of a binge-eating episode. For some indi-

viduals, the sense of loss of control associated with

eating ‘forbidden’ foods such as two biscuits or a

piece of cake may constitute a qualitative or subject-

ive binge, whereas there is consensus that eating more

than is normal under the circumstances constitutes a

quantitative or objective binge. The accuracy of self-

reported binge-eating quantities hampers research

in BN.

0026 The diagnosis of BN must be considered in the

absence of disclosure by the individual where seque-

lae such as unexplained low potassium are evident.

BN may also contribute to disruption of normal men-

strual function among women of a statistically

normal body weight.

Treatment

0027 The treatment of BN includes but is not limited to the

reestablishment of normal eating behavior, whether

through education, psychotherapy, or drug therapy.

Unlike AN, individuals with BN are often eager to

overcome their eating disturbance, although this is

accompanied by a morbid fear of weight gain.

0028Treatment begins with a careful history which in-

cludes longitudinal weight history, including weight

prior to the onset of dieting and desired weight; the

discrepancy may reflect a conflict between culture

and biology. The acute precipitants of binge-eating

states are identified and the nonbinge meals are quan-

tified. Methods of purgation and their potentially

lethal complications are elicited. The associations

between psychological states, eating behaviors, and

weight and shape concerns may be facilitated by self-

report diaries where individuals with BN discover

these connections. Unlike AN, weight gain may not

be a goal but weight stabilization may occur as a

result of cessation of dieting and bulimic behaviors;

typically, these individuals experience significant

weight fluctuations.

0029An educational approach may include readings on

cultural bias and body weight, the effect of dietary

chaos and deprivation on physiological and psycho-

logical states as well as eating behavior, and the bio-

logical regulation of body weight. Indeed, research

demonstrates that guided reading may be an effective

first step in the treatment of individuals with BN.

Individual psychotherapy may explore the origins

and extent of dysfunctional attitudes related to

eating, weight, and shape, as well as more global

underlying disturbances related to self-esteem and

self-appraisal; this approach, entitled cognitive be-

havioral therapy, is the most validated treatment for

BN and is usually administered over 8–20 sessions.

Often a specific meal plan may be prescribed, not

to promote weight gain but to avoid long intervals

of deprivation that may precipitate binge eating.

Learning to tolerate feelings and impulses through

understanding, or through learning more adaptive

coping strategies, may also be useful. Interestingly,

research evidence also supports the efficacy of another

short-term intervention called interpersonal therapy,

which focuses on current relationships and does not

include direct examination of eating behavior.

0030The use of a wide range of antidepressant drugs

has been studied since 1983. The early evidence con-

firmed that tricyclic antidepressants, monoamine oxi-

dase inhibitor antidepressants, and selective serotonin

reuptake inhibitor antidepressants exert an antibuli-

mic effect which is independent of their effect on

mood. The most extensively studied and validated

such antidepressant is fluoxetine, which is licenced

for the treatment of BN in many countries. Their

mechanism of action in BN is unclear but may

relate to effects on neurotransmitters involved in

712 BULIMIA NERVOSA

hypothalamic regulation of appetitive behavior. Ex-

tensive abnormalities of serotonin and norepineph-

rine (noradrenaline) have been documented in BN.

More recent studies which have compared and

combined antidepressants and individual cognitive

behavioral therapy have suggested that while both

are effective alone, the combination confers no par-

ticular advantage and there is greater compliance and

duration of effect with psychotherapy. To date, no

predictor variables exist which will help determine

which of these disparate treatments will be most ef-

fective for an affected individual.

0031 Hospitalization is rarely necessary for individuals

with BN. However, when the disorder is accompanied

by suicidal tendencies, serious electrolyte com-

promise, or coexistent diabetes mellitus, hospitaliza-

tion may assist in crisis resolution or metabolic

stabilization.

Prognosis

0032 The long-term prognosis of BN is relatively less well

known than for AN because of the recency of both

description of the disorder and the development of

effective interventions. It is known that individuals

with BN are vulnerable to mood, anxiety, and sub-

stance misuse disorders, as well as a general impair-

ment in social adjustment. Some follow-up studies of

5 years indicate that two-thirds of the treated sample

recovered from BN; low self-esteem at the onset of

treatment and persistent vomiting at the end of treat-

ment have been identified as poor prognostic factors.

In contrast to AN, the mortality rate of BN is very low

(0.3%) in outcome research.

See also: Adolescents; Anorexia Nervosa; Famine,

Starvation, and Fasting; Premenstrual Syndrome:

Nutritional Aspects; Slimming: Slimming Diets;

Metabolic Conseqences of Slimming Diets and Weight

Maintenance