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organelle, have allowed the generic syndrome (of

malabsorption) to be subdivided into disorders

affecting specific stages in the physiological sequence

of nutrient assimilation. The term malabsorption syn-

drome has therefore come to include a wide variety of

clinical disorders of the following:

0002 Intraluminal digestion (strictly speaking, mal-

digestion syndromes).

0003 Intestinal absorption.

0004 Carbohydrate absorption.

0005 A number of specific defects in intestinal uptake or

transport have also been described. These concern

elements (zinc, magnesium, copper), amino acids

(cystinuria, Hartnup disease, blue diaper, oast-

house, Lowe’s and Joseph’s syndromes; lysinuric

protein intolerance, etc.), and hematinics (vitamin

, folic acid), but are not usually associated with

stool abnormality.

0006There is also a miscellaneous group of disorders in

which the cause of the diarrhea is uncertain. Here

the only condition of clinical importance is so-called

toddler’s diarrhea.This group also includes very rare

malabsorption statessuchasthatcausedbyneuroen-

docrine-secreting tumors (e.g., ganglioneuroma).

(See Celiac (Coeliac) Disease; Cystic Fibrosis.)

Disorders of Intraluminal Digestion (DID)

(Table 1)

0007Diarrhea caused by exocrine pancreatic insufficiency

(EPI) is the principal cause of DID. The physical

characteristics of the stools are striking. They tend

tbl0001 Table 1 Disorders of intraluminal digestion

Pathophysiology Diagnosis Supportingevidence

Maldigestion of all macronutrients

Exocrine pancreatic insufficiency Cystic fibrosis Sweat chloride > 65 mmol l

1

Pancreatic hypoplasia (lipomatosis) Neutropenia, metaphyseal dysplasia

(Shwachman-Diamond syndrome)

(Johanson-Blizzard syndrome) (fibrosis) Ectodermal defects

(Pearson syndrome) Sideroblastic anemia

Severe malnutrition Clinical circumstances

Pancreatic trauma (pseudocyst) History of abdominal trauma

Chronic pancreatitis Clinical history, plasma amylase

Multiple endocrine deficiency,

autoimmune candidiasis syndrome

Hypoparathyroidism or other

endocrinopathies

Cystinosis Tubular dysfunction

Advancedceliacdisease Table 2

Inactivation of pancreatic enzymes

(Zollinger-Ellison syndrome; ZES)

Peptic ulcers, fasting serum gastrin

>100 pg ml

1

Maldigestion of fat alone

Pancreatic secretion Congenital lipase or colipase deficiency Assay in duodenal contents

Bile salts

Synthesis-secretion Extrahepatic biliary atresia Cholestasis, liver biopsy

Intrahepatic bile duct hypoplasia Pulmonary artery stenoses, embryotoxon

Various syndromes

of infantile cholestasis

Hepatic cirrhosis

Preterm or

mature newborn

Liver biopsy

Impaired bile acid

synthesis

Assay bile salts

(ABS) duodenum, blood, stool

Deconjugation Bacterial overgrowth proximal

small bowel (obstruction, anastomoses,

disturbed motility, blind loops)

Clinical history, H

breath test, trial of

lincomycin

Enterohepatic circulation broken Ileal resection(s) fistulae, Crohn’s disease Clinical history, radiology, tissue biopsy

Congenital malabsorption of bile salts ABS duodenum, blood, stool

Precipitation, etc. ZES See above

Drugs: neomycin, laxatives, cholestyramine,

sulphonamides

Clinical history

Maldigestion of proteins alone Congenital enterokinase deficiency Assay in duodenal mucosa

Congential trypsinogen defiency Assay in duodenal contents

3654 MALABSORPTION SYNDROME

to be loose and homogenous, pale and pasty with an

offensive, penetrating, cheesy odor. These are often

greasy and patients describe undigested dietary fat

oozing like oil from the passed stool or floating on

the water surface in the toilet. Under the microscope,

fat droplets and partially digested meat fibers are

seen. Balance studies reveal a more bulky stool than

normal, containing large amounts of fat, nitrogen,

and volatile fatty acids. The coefficient of fat absorp-

tion varies from 40% to 70%. Huge nitrogen losses of

up to 3–4 g day

1

(normal < 0.5 g day

1

) are also

recorded. Volatile fatty acids – acetic, butyric, and

propionic – are usually > 30 mmol day

1

(normal

< 10 mmol day

1

), although only trace or small

amounts of lactic acid are present. These large fecal

losses are typical of EPI, the commonest cause of

which is cystic fibrosis. If the sweat chloride level is

normal, however, the cause is likely to be congenital

hypoplasia of the pancreas, several forms of which

have been described, each with distinct extraalimen-

tary features. (See Fats: Digestion, Absorption, and

Transport; Gallbladder.)

0008 Disorders of intraluminal digestion may occasion-

ally affect only one class of nutrient. Congenital

absence of pancreatic lipase results in a massive stea-

torrhea, which may be confirmed by enzymatic assay

of lipase activity in aspirated duodenal contents. In

isolated colipase deficiency steatorrhea is less severe.

0009 Where the jejunal bile salts level falls below the

critical physiological concentration, impaired micel-

lar solubilization results in severe malabsorption of

dietary fat and fat-soluble vitamins. Absorption of

nitrogen and carbohydrate is normal. This is most

usually seen in children with obstructive jaundice,

such as extrahepatic biliary atresia or intrahepatic

cholestasis (e.g., Alagille’s syndrome). When choles-

tasis is complete or hepatocellular failure is present,

fat excretion tends to be greater and may reach

20 g day

1

(normal up to 4.3 g day

1

). Fatty acids

with one or more double bonds are malabsorbed, as

well as saturated fats. In extensive Crohn’s disease or

surgical resection of the terminal ileum, there may be

failure to absorb sufficient bile salts to maintain their

enterohepatic circulation (and pool size), which is

said to be broken. Inborn errors in both the synthesis

and the absorption of bile acids have also been

reported in occasional families. The Zollinger–Ellison

syndrome (ZES), by markedly lowering jejunal pH

and also the action of certain drugs (e.g., neomycin),

interferes with the complex of events which affect

intraluminal digestion. (See Inborn Errors of Metab-

olism: Overview.)

0010 Isolated, massive proteolytic insufficiency has been

described in the rare inherited disorder congenital

enterokinase deficiency. This can be confirmed by

finding reduced or absent proteolytic activity in duo-

denal fluid and assay of small-bowel mucosal enter-

okinase activity.

Disorders of Intestinal Absorption (DIA)

(Table 2)

0011Although usually not fatty-looking, the stool is loose

or watery, often with an acidic smell. Balance studies

show that stool volume is more variable than in EPI

and steatorrhea, and stool nitrogen losses are moder-

ate (coefficient of fat absorption, 70–85%; nitrogen

excretion, 1–2 g day

1

, respectively). Stool volatile

fatty acids and lactic acid are modestly increased.

Sheaves of fatty acid crystals may be appreciated

microscopically.

0012Small-bowel capsule biopsy may reveal a non-

specific enteropathy with either a flat jejunal mucosa

(subtotal or total villous atrophy) or a degree of par-

tial villous atrophy (PVA). The degree of atrophy of

the mucosa is but one feature of histological abnor-

malities which include the presence of enterocyte

damage, crypt hyperplasia, cellular infiltration, and

edema of mucosa and lamina propria. A flat jejunal

mucosa in a child greater than 9–12 months of age is

highly suggestive of celiac disease. This is confirmed

by observing the clinical and histological response to

exclusion of dietary wheat or rye gluten. The Euro-

pean Society for Paediatric Gastroenterology and Nu-

trition (ESPGAN) diagnostic criteria for celiac disease

are as follows: (1) small-bowel mucosa usually flat;

(2) clinical and histological improvement on a gluten-

free diet; (3) histological, and sometimes clinical,

relapse following dietary gluten challenge.

0013Partial villous atrophy is found in various dis-

orders: under 6 months of age it is most likely to be

caused by food protein intolerance(s) – most often

cows’ milk protein, less often to soya, wheat, rice,

or multiple food proteins. Other causes include post-

infective enteritis syndrome or Giardia lamblia infest-

ation, where motile trophozoites may be seen in

aspirated intestinal juice and histologically in the

jejunal crypts. PVA has also been reported in various

immunodeficiency states. Small-bowel bacterial over-

growth might be responsible, possibly linked to

deconjugation of intraluminal bile salts. A very simi-

lar bowel lesion is found in infants with the syndrome

of protracted diarrhea in which a combination of

factors may be etiological – primary bowel infection,

food intolerance, subadequate nutrition, a depressed

immune status, bacterial overgrowth, etc.

0014A specific lesion on small-bowel biopsy is much

more rarely found. In abetalipoproteinemia, mucosal

architecture is generally normal but there is a dense

accumulation of triglyceride droplets, especially

MALABSORPTION SYNDROME 3655

within mature enterocytes. This may be confirmed by

the presence of peripheral blood acanthocytes and

absent very-low-density lipoprotein (VLDL), low-

density lipoprotein (LDL), and apolipoprotein B in

plasma. There is severe impairment, if not virtual

absence, of absorption of fat-soluble vitamins. Ander-

son’s disease is a genetically distinct but similar dis-

order of chylomicron release. In each of these

disorders early clinical features are similar to celiac

disease. In intestinal lymphangiectasia, dysmorphic

lacteals distort the normal villous contours and

there is mild steatorrhea with evidence of a protein-

losing enteropathy and lymphopenia. Infiltration by

clones of abnormal or neoplastic cells (a-chain

disease, histiocytosis X, tumor) has occasionally

been reported. Crohn’s disease may also involve the

proximal small bowel. (See Lipoproteins.)

Disorders of Carbohydrate Absorption

(DCA) (Table 3)

0015The DCA form a heterogeneous group of disorders, the

common feature of which is carbohydrate malabsorp-

tion. The stool contains large amounts of volatile fatty

acids. It is the presence of these small, osmotically

active molecules (stool osmolality is greater than

tbl0002 Table 2 Disorders of intestinal absorption

Pathophysiology Diagnosis Supportingevidence

Intestinal biopsy: nonspecific inflammatory

lesion

Flat mucosa (total or subtotal villous atrophy) Celiac disease ESPGAN criteria (see text)

Partial villous atrophy (in severe cases

villous atrophy may be subtotal)

Food protein intolerance (various

– CMP, wheat, rice, etc.)

Response exclusion diet and challenge

(see Table 3)

Postenteritis syndrome Clinical history

Dermatitis herpetiformis Dermal IgA deposit

Giardia lamblia infestation Trophozoites in jejunal juice/biopsy

Immune deficiency states

(hypogamma; SCIDS)

Plasma Ig, etc.

Radiation damage, drugs

(e.g., methotrexate, neomycin)

Clinical history

Eosinophilic gastroenteropathy Anemia, eosinophilia, jejunal biopsy

Graft-versus-host disease Clinical history

Intractable diarrhea Clinical history

Intestinal biopsy: specific lesions

Fat-filled enterocytes Abetalipoproteinemia Acanthocytes, absence plasma VLDL.

LDL, apo-B

Anderson’s disease Decreased plasma VLDL, LDL, apo-B

Villi distorted by ectatic lymphatics Lymphangiectasia Protein-losing state, lymphopenia

Mucosal infiltration a-Chain disease Monoclonal abnormal plasma IgA

Histiocytosis X CT scan brain, tissue biopsy

Crohn’s disease, lymphoma, tumor Clinical history, tissue biopsy

Intestinal biopsy: normal Lysinuric protein intolerance Dibasic aminoaciduria, osteoporosis

Congenital chloride-losing diarrhea Hydramnios, stool electrolytes

Specificdisaccharidasedeficiencies Table 3

Transport defects: amino acids; zinc,

copper; vitamin B

, folic acid

Not part of malabsorption syndrome triad

CMP, cows’ milk protein; SCIDS, severe combined immune-deficiency syndrome; IgA, immunoglobulin A; VLDL, very-low-density lipoprotein; LDL, low-

density lipoprotein; apo-B, apolipoprotein B; CT, computed tomography.

tbl0003 Table 3 Disorders of carbohydrate absorption

Pathophysiology Diagnosis Supporting evidence

Intestinal biopsy: normal or

almost normal

Congenital sucrase–isomaltase,

congenital lactase, late-onset lactase,

and congenital trehalase deficiencies

Assay disaccharidases jejunal mucosa;

one specific activity affected

Congenital glucose–galactose deficiency In Ussing chamber, absence of glucose-

induced short-circuit current

Intestinal biopsy: nonspecific

inflammatory lesion

Acquired carbohydrate intolerances, especially

celiac disease, cows’ milk protein intolerance,

postenteritis syndrome

Allmucosaldisaccharidasesaffected; Table 2

3656 MALABSORPTION SYNDROME

2[Na

þK

]) that determines stool volume, which is

therefore largely proportional to the amount of carbo-

hydrate ingested. Stool lactic acid is increased and,

accordingly, its pH is < 5.5. Large amounts of hydro-

gen, generated during the process of colonic fermenta-

tion and passed as flatus, form the basis of the breath

hydrogen test. Stool fat and nitrogen tend to be normal.

Reducing substances (sugars) can be detected by adding

equal volumes of stool and tap water to a Clinitest

tablet. A color change toward orange indicates the

presence of up to 2% reducing sugar. (Sucrose is not a

reducing sugar and must first be hydrolysed by

0.1 mol l

1

hydrochloric acid.) (See Carbohydrates:

Digestion, Absorption, and Metabolism.)

0016 If, as is more likely, a nonspecific inflammatory

lesion is present, causation has been discussed

(Table 2). Disaccharidase and peptidase activities

are reduced in the microvilli. Such secondary changes

in celiac disease may be the main factor responsible

for stool volume. A variety of specific inherited

disorders of sugar absorption have also been de-

scribed in the presence of microscopically normal

jejunal mucosa. Specific enzymatic assay of mucosal

disaccharidases, or more sophisticated studies, will

confirm the diagnosis.

0017 In the rare condition of congenital microvillous

atrophy, electron microscopy reveals the presence of

abortive microvilli as intracellular enterocyte inclu-

sions with extreme stunting or absence of microvilli

projecting into the lumen. As would be expected,

carbohydrate intolerance, secretory diarrhea, and

severe malabsorption result. In the majority of

patients the outcome is fatal.

Clinical Features

0018 The principal clinical expression of malabsorption is

diarrhea. When this becomes a chronic symptom, i.e.,

of more than 14 days’ duration, malnutrition and

failure to thrive may follow. Depending upon eti-

ology, nutritional failure may be compounded by

symptoms such as poor appetite, anorexia, abdom-

inal pain, or vomiting.

0019 A careful clinical history will focus first upon stool

number, size, color, smell, and fluidity. The pale,

cheesy, homogeneous stools of cystic fibrosis, the

loose, bulky motion of celiac disease, and the watery

stool passed with much flatus of the child with sugar

malabsorption have already been referred to.

0020 The mode of onset of diarrhea is of special im-

portance and may provide the most important pointer

to diagnosis. For example, an onset at birth might

suggest a congenital absorptive anomaly, such as

chloridorrhea. Watery diarrhea which persists on

treatment with intravenous fluid suggests a secretory

diarrhea, such as congenital microvillous atrophy.

Symptoms may be related to dietary changes:

that from breast to cows’ milk (cows’ milk protein

intolerance), introduction of cane sugar (sucrase–

isomaltase deficiency), or weaning on to wheat- or

rye-containing foods (celiac disease). There may be a

close family history of similar patients. Persisting

diarrhea may follow acute gastroenteritis and suggest

postinfective enteritis syndrome with accompanying

dietary sugar or protein intolerances.

0021Associated symptoms can be important: for

example, weakness, anorexia, or vomiting may sug-

gest celiac disease; increased appetite or pulmonary

symptoms cystic fibrosis; dyspepsia, abdominal

cramps, perianal pain, or discomfort may suggest

Crohn’s disease; bloating, abdominal cramps, or dis-

comfort may suggest sugar malabsorption. Extrain-

testinal complaints are especially important in cystic

fibrosis, Crohn’s disease, and immune deficiencies.

0022The aims of the physical examination are essen-

tially: (1) to determine clinical pointers toward a

specific diagnosis and (2) to assess the degree of mal-

nutrition. The general appearance of the child is pos-

sibly of greatest benefit, together with comparison of

height (or length) and weight with charts of normal

growth. Parental height is relevant in short children,

together with any previous known weight or height

measurements (calculate growth velocity) which may

show age-related evolution of the condition. The

Tanner stages of puberty may indicate delay in sexual

maturation.

0023A measure of malnutrition is provided by the

degree of weight loss, best seen as wasting of subcuta-

neous fat and/or muscle bulk around the groins,

buttocks, shoulder girdles and neck. Malnourished

children under 2 years of age often show delayed

psychomotor development. Abdominal distention

should be assessed in profile, allowing for the tod-

dler’s exaggerated lumbar lordosis. The presence

of dehydration, edema of face or extremities, skin

or conjunctival pallor, hair quality, and length of

eyelashes should be assessed. The presence of chest

deformity, finger clubbing, perianal abnormalities

(e.g., excoriation, superficial ulceration, edema,

fissures, fistulae, tags), skin rashes (e.g., erythema

nodosum) and arthritis may be of great diagnostic

assistance. The oropharynx should be carefully exam-

ined. Cheilosis and aphthous ulceration are seen in

celiac disease, while in Crohn’s disease there may be

shallow ulcers, furrowed tag-like nodules, or swollen,

inflamed, fissured lips.

0024In spite of much evidence of protein and energy

malnutrition in the malabsorption syndromes, evi-

dence of vitamin deficiencies is surprisingly un-

common, with the exception that in prolonged

MALABSORPTION SYNDROME 3657

obstructive jaundice clinical stigmata of fat-soluble

vitamin deficiency are often found, e.g., defective

dark adaptation, osteomalacia, bone pain, fractures,

and a coagulopathy. Neurological features – loss of

deep tendon reflexes and proprioception with ataxia,

nystagmus, ophthalmoplegia, and retinitis pigmen-

tosa – have been seen as a result of protracted defi-

ciencies of vitamins E and A. Similar features have

been reported in abetalipoproteinemia and, less com-

monly, in cystic fibrosis. In chronic small-bowel dis-

orders (celiac disease, Crohn’s disease), there may be

angular stomatitis and other evidence of vitamin B

complex deficiencies.

0025 Two very common and confusing disorders are

toddler’s diarrhea (nonspecific chronic diarrhea)

and the postenteritis syndrome. The former is

characterized by persistent bouts of loose, mucusy,

foul-smelling stools which often contain undigested

vegetable material, punctuated by periods of normal

or infrequent stools. Absorption and nutrition, well-

being, and growth are normal. Postenteritis syndrome

follows mucosal damage by enteric viruses or bac-

teria, and is in part caused by diminished enzyme

activity in the damaged enterocytes. It persists until

a new generation of normal enterocytes has been

developed, a process which takes much longer in the

malnourished patient.

0026 Unless a sweat test or a jejunal biopsy reveals a

diagnosis of cystic fibrosis or celiac disease, more

detailed studies will be required. Careful 3-day bal-

ance studies of net intake and excretion, although

used less frequently than in former times, may be

necessary to identify malabsorption together with

specific investigations set out in Tables 1–3.

The Consequent Malnutrition

0027 Malnutrition varies a great deal and will depend on

both the child’s age and the diagnosis. The greater the

age-related demands of growth, the more severe will

be the effects upon nutrition, particularly in the first

2–3 years of life. In general, macronutrient malab-

sorption is more severe when the pathophysiological

abnormality occurs in the intraluminal phase of the

assimilation sequence. Thus EPI is associated with

greater fecal losses of fat and protein than are celiac

disease or disorders of lymphatic transport. The same

cannot be said of micronutrient malabsorption,

which tends to be relatively more severe in DIA,

e.g., in celiac disease or extensive small-bowel

Crohn’s disease. Fat-soluble and probably water-

soluble vitamins, minerals (iron, calcium), folic acid,

vitamin B

, and trace elements (zinc, magnesium) are

poorly absorbed. In a specific, inherited condition

such as abetalipoproteinemia there is profound,

refractory deficiency of all fat-soluble vitamins (see

above). (See Malnutrition: The Problem of Malnutri-

tion and also individual nutrients.)

0028It should be pointed out, however, that important

factors other than maldigestion or malabsorption

contribute significantly to the degree of nutritional

failure:

0029Poor dietary intake is probably the most import-

ant factor and is the result of poor appetite, altered

taste, dyspepsia, vomiting, and abdominal dis-

comfort or frank abdominal pain. These symp-

toms are relatively common in celiac disease and

small-bowel Crohn’s disease. In DCA a poor diet

probably accounts for virtually all of the malnu-

trition.

0030Cystic fibrosis is an example of a disorder in

which, in early life, the child may compensate for

the considerably increased fecal losses by an in-

crease in dietary intake. With the development of

bronchopulmonary infections, however, appetite

wanes, growth velocity diminishes, weight is lost,

and this is compounded by increased work of

breathing and, perhaps, elevation of resting energy

expenditure.

0031Protein-losing states are associated with a three-

fold increase in the fractional catabolic rate of the

plasma albumin pool which is not compensated by

increased hepatic synthesis of up to 24%. This

may be a factor in, for example, up to one-third

of children with celiac disease; it is also common in

Crohn’s disease, intestinal lymphangiectasia, and

eosinophilic gastroenteropathy. (See Protein: Syn-

thesis and Turnover.)

0032Chronic inflammation has been shown in Crohn’s

disease to increase protein turnover with a conse-

quent increase in resting metabolism.

0033Small-bowel bacterial overgrowth leads to further

nitrogen loss and hypoalbuminemia, and results in

sugar intolerance and steatorrhea.

0034In addition to malabsorption, each of these

developments result in protein malnutrition with

consequent lowering of plasma levels of insulin-like

growth factor 1 (IGF-1, somatomedin C, basic soma-

tomedin). This possibly explains why the growth rate

is usually reduced, even though secretion of growth

hormone, thyroid, and adrenal hormones is unim-

paired. Where malnutrition is severe or long-lasting,

IGF-2 may eventually be depressed also. The precise

means by which nutrition influences IGF-1 produc-

tion in liver and other tissues is unclear, although

intake of protein and energy appears to be important.

None the less, IGF-1 seems to be more sensitive than

other commonly used indices of malnutrition, such as

prealbumin, retinol-binding protein, or transferrin.

3658 MALABSORPTION SYNDROME

Likewise, when nutrition is corrected, IGF-1 increases

more rapidly and to a greater degree than the other

proteins. Clinically, serial measurement of IGF-1 has

been proposed as a means of following nutritional

progress in gastrointestinal disorders, such as chronic

inflammatory bowel disease. (See Colon: Diseases

and Disorders.)

0035 Weight loss (wasting) of course occurs before re-

duction in height or length velocity results in stunting.

The effects are seen most obviously in the infant and

toddler. In the past, children occasionally presented

with celiac disease in a state of crisis (vomiting,

hypoalbuminemia, hypovolemia) which had a signifi-

cant mortality. In older, untreated children, the effects

on growth are less dramatic, although there tends to

be a progressive falling away from the normal range

of weight- and height-for-age. In adolescents this

is associated with delayed pubertal development,

psychological, and peer-group maladjustment and,

ultimately, a reduced adult height. Reference has al-

ready been made to the specific effects of vitamin and

mineral deficiencies.

Nutritional Management

0036 Nutritional management should begin with diagnosis

and thence a rational approach to management.

Where there is deficiency, this is replaced, as for

example in cystic fibrosis (pancreatic enzyme supple-

ments must match the load of macronutrient being

ingested, whereas in congenital enterokinase defi-

ciency a small amount of enzyme (trypsin) is suffi-

cient to activate pancreatic proenzymes secreted

into the duodenum). Alternatively, the substrate

is avoided or altered, as in congenital sucrase–

isomaltase deficiency (dietary sucrose omitted); in

congenital glucose–galactose malabsorption, dietary

glucose and lactose are replaced by fructose. In celiac

disease, a gluten-free diet is prescribed and it must be

both strict and lifelong, provided that the diagnosis

has been made according to ESPGAN criteria. (See

Carbohydrates: Metabolism of Sugars.)

0037 In many malabsorption disorders, however,

management is nonspecific, and consists of dietary

manipulations which ameliorate the pathophysiology

and correct malnutrition by minimizing the degree of

malabsorption. For example, in disorders in which

there is sub-optimal small-bowel bile salt concentra-

tion (Table 1), a large proportion of dietary long-

chain triglycerides (LCTs) are substituted by

medium-chain triglyceride (MCT) which fully cor-

rects the steatorrhea. In practice, this is simpler in

infants, where a variety of commercially available

formulae provide a feed with up to 80% of the lipid

as MCT. It is important, however, to insure that the

diet contains adequate amounts of essential fatty

acids, either in the form of LCT or as a supplement

of linoleic acid (e.g., safflower oil). Generous oral

supplements of fat-soluble vitamins should be pre-

scribed, but if this fails to produce normal plasma

levels, parenteral preparations, especially of vitamins

A and E, should be administered.

0038Where there has been extensive ileal resection or

pathology which interferes significantly with the

enterohepatic circulation of bile salts, cholestyramine

may be required in addition to MCT, in order to

prevent the production of disabling cholerrheic diar-

rhea; this results when large quantities of bile salts

pass into the colon and inhibit electrolyte and water

absorption. When cholestyramine is being used, sup-

plements of fat-soluble vitamins and folic acid are

required since these will be unavailable for absorp-

tion as they become bound to the anionic resin;

supplements should be administered at times other

than when the drug is being taken.

0039In the small, severely malnourished infant or tod-

dler, prior to, or immediately after, diagnosis, there is

often a need to replace enteral nutrition with a bal-

anced intravenous supplementation mixture (amino

acids, glucose, fat, electrolytes, minerals, vitamins,

and trace elements). The classic example is the baby

with intractable diarrhea (Table 2) for whom survival

may depend upon this approach. Supplementing the

oral intake using a glucose polymer, usually with a

source of lipid (often rich in MCT), vitamins, and

minerals, is reserved for those who are less ill and

able to tolerate the extra oral intake (e.g., those with

cystic fibrosis or celiac disease). Nasogastric feeding

may be necessary if poor appetite, nausea, or other

problems interfere with achieving a satisfactory

nutrient intake. When longer-term supplementation

is required, especially in older patients, a percutan-

eous, endoscopically positioned gastrostomy may be

employed.

0040Such nutritional additives need to be used judi-

ciously, starting with smaller volumes in order not

to increase the diarrhea already present – as when

excessive amounts of glucose polymer are used. Cau-

tion is needed in infants with advanced liver disease,

or those with hypoalbuminemia, lest the feed volume

per se precipitate fluid retention. Supplements of

intravenous salt-poor human albumin may be

necessary.

0041Finally, knowledge of a specific pathophysiological

abnormality may suggest an appropriate therapy.

For example, patients with abetalipoproteinemia,

Anderson’s disease and congenital lymphangiectasia

respond well to oral MCTsubstituted for LCT. This re-

lates to the fact that MCT is absorbed directly into the

portal venous system rather than via the small-bowel

MALABSORPTION SYNDROME 3659

lacteals. In addition, supplements of fat-soluble vita-

mins are required both to prevent nutritional, particu-

larly neurological sequelae and to treat those who are

already showing clinical deficiency.

0042 In disorders of carbohydrate absorption, avoidance

of the offending dietary sugar is usually sufficient,

although rehydration may also be necessary, together

with the general management of the severely mal-

nourished child.

See also: Carbohydrates: Digestion, Absorption, and

Metabolism; Metabolism of Sugars; Celiac (Coeliac)

Disease; Colon: Diseases and Disorders; Cystic

Fibrosis; Fats: Digestion, Absorption, and Transport;

Gallbladder; Inborn Errors of Metabolism: Overview;

Lipoproteins; Malnutrition: The Problem of Malnutrition;

Protein: Synthesis and Turnover

Further Reading

Anderson CM, Burke V and Gracey M (eds) (1987) Paedi-

atric Gastroenterology, 2nd edn. Melbourne: Blackwell

Scientific Publications.

Lebenthal E (ed.) (1981) Textbook of Gastroenterology and

Nutrition in Infancy. New York: Raven Press.

Walker WA, Durie PR, Hamilton JR, Walker-Smith JA and

Watkins JB (1991) Pediatric Gastroenterology Disease –

Pathophysiology, Diagnosis, Management. Phila-

delphia: BC Decker.

MALNUTRITION

Contents

The Problem of Malnutrition

Malnutrition in Developed Countries

The Problem of Malnutrition

K K Sinha, T.M. Bhagalpur University, Bhagalpur,

India

Background

0001 Malnutrition literally means ‘bad nutrition’ and

refers to the imbalance between the body’s supply

and demands for nutrition. Thus, malnutrition can

be defined as ‘an impairment of health resulting

from a deficiency, excess, or imbalance of nutrients.’

0002 It can be classified further into ‘undernutrition’ and

‘overnutrition.’ Undernutrition deals with the defi-

ciency of nutrients and their consequences, while

overnutrition relates with cases of consumption of

excess nutrients and their effects. In this communi-

cation, the problem of malnutrition has been dis-

cussed under various heads, viz. causes and signs

of malnutrition as well as the important diseases

induced by the deficiency of essential nutrients.

Causes of Malnutrition

Overnutrition

0003 Problems resulting from overnutrition are known to

be comparatively less common than the problems

associated with undernutrition. So many persons con-

sume diets that are excessively high in calories, satur-

ated fat, cholesterol, and sugars and that are also

excessively refined. Each of these excesses is supposed

to be one of the major factors for increasing the risk

of chronic diseases.

0004Excessive caloric intake leads to obesity, which is

highly prevalent in urban population. Obesity can

also be seen in persons who sit in their offices for

longer duration. In fact, these persons may not take

food in excess of their requirements, but the poor

physical activities fail to consume the energy they

receive daily. In these circumstances, the normal diet

may prove to be an overdiet, and the extra energy

made available goes for deposition. Obesity may lead

to many chronic diseases like diabetes mellitus, gall

bladder disease, gout, cardiovascular diseases, etc.

Excessive intake of fats and sugars may also induce

some of the chronic diseases described earlier.

0005Consumption of excess amount of saturated fats

and cholesterol are believed to be among the import-

ant risk factors in the incidence of cardiovascular and

cerebrovascular diseases, while excessive intake of

salt may lead to hypertension. An increase in the

incidence of gastrointestinal disorders like diverticu-

losis, irritable colon, and possibly colon cancer has

also been reported to be caused by the consumption

of excessive refined foods.

3660 MALNUTRITION/The Problem of Malnutrition

0006 Vitamins A and D are essential for human health,

but consumption of excessive amounts of these vita-

mins may lead to toxicosis, which is characterized by

dry itchy skin, lethargy, fatigue, general weakness,

nausea, vomiting, headache, etc.

Undernutrition

0007 Many problems have been related to cases of under-

nutrition or nutritional deficiencies. Primary malnu-

trition is the result of an insufficient intake of

essential nutrients, because of the unavailability of a

food supply, ignorance, or poverty. The regional un-

availability of food and crop failure are basic causes

of undernutrition in most parts of the world. Like-

wise, poor practices in processing, marketing, and

storage can result in a serious reduction of the avail-

able food supply as well as losses in the nutritive

values of foods consumed. Some of the important

causes for inadequate consumption of food that can

be prevented by sufficient motivation, knowledge,

and income are as follows:

0008 lack of knowledge about kinds and amounts of

food to be taken at specific growth periods;

0009 lack of means to procure foods essential for good

nutrition;

0010 poor and faulty environment at the time of food

consumption;

0011 refusal to take food due to poor appetite caused by

prolonged illness or allergy to some specific foods;

0012 lack of teeth and inability to chew certain nutritive

foods; and

0013 loss of desire to eat good foods owing to loneliness.

0014 Several causes of malnutrition in individuals are

not necessarily the result of a deficient dietary intake

but are caused by physiologic failure beyond the

ingestion stage. For example, a nutritional deficiency

may develop as a result of a failure to absorb nor-

mally an essential nutrient that is supplied by the diet

in adequate quantities. Similarly, nutritional defi-

ciency may be brought about by impaired digestion,

abnormal intermediate metabolism, excessive excre-

tion, and increased biologic requirements. Such sec-

ondary or conditioned deficiencies may occur in the

case of gastrointestinal diseases with rapid emptying

time, vomiting, and diarrhea; in pancreatic or biliary

diseases that interfere with normal digestion and

absorption; in liver diseases with impaired hepatic

function or when rapid growth, closely spaced preg-

nancies, lactation, surgery, injuries, extensive burns,

or febrile or metabolic diseases increase the body’s

requirement for one or more nutrients.

0015The conditions that predispose to nutritional defi-

ciency are usually multiple and simultaneous in oper-

ation. In most of the underdeveloped areas of the

world, widespread malnutrition is not just the result

of one factor, poverty; ignorance, religious or cultural

taboos, and intercurrent chronic parasitic infection

also play an important compounding role. If more

than one predisposing condition is working naturally,

more than one nutritional factor is in deficient supply.

Underweight preschool children are prevalent in

different parts of the world (Table 1).

0016Thus, the individual who suffers from a well-

defined deficiency of a single essential nutrient is the

exception. As a rule, a number of deficiencies involv-

ing more than one dietary factor are at work concur-

rently, bringing about an impaired nutritional status

and multifaceted disease picture simultaneously or

sequentially. The occurrence of simultaneous multiple

deficiencies complicates the nutritional rehabilitation

of the malnourished individual considerably. The

tbl0001 Table 1 Estimated prevalence and number of underweight preschool children, 1995–2005

UN regions and subregions Prevalence of underweight (%) Number of underweight (million)

1995 2000 2005 1995 2000 2005

Africa 27.9 28.5 29.1 34.03 38.32 42.45

Eastern 33.2 35.9 38.7 13.42 16.47 19.48

Northern 14.8 14.0 13.2 3.11 3.08 2.99

Western 34.9 36.5 38.1 13.34 15.41 17.66

Asia 32.8 29.0 25.3 121.03 107.91 93.16

South Central 47.3 43.6 40.0 82.40 78.49 73.48

South-east 32.6 28.9 25.3 18.56 16.68 14.27

Latin America and the Caribbean 8.3 6.3 4.3 4.48 3.40 2.35

Caribbean 14.4 11.5 8.7 0.54 0.43 0.32

Central America 15.3 15.4 15.4 2.46 2.52 2.51

South America 5.7 3.2 2.3 1.96 1.08 0.80

Oceania na na na na na na

All developing countries 29.2 26.7 24.3 159.55 149.63 137.95

na, not available.

Source: ACC/SCN (2000) Fourth Report on the World Nutrition Situation. Geneva: WHO.

MALNUTRITION/The Problem of Malnutrition 3661

treatment of a single deficiency in a chronically mal-

nourished patient is as effective in bringing about an

improvement as the granting of a loan to settle a

single debt of a business burdened by a long-standing

accumulation of financial obligations.

Signs of Undernutrition

0017 As discussed earlier, undernutrition leads to several

classic deficiency diseases, which are more prevalent

in the developing and underdeveloped countries and

can be diagnosed easily on the basis of their specific

symptoms. However, there are some common phys-

ical, behavioral, and pathological signs that can be

observed in people affected by undernutrition. In fact,

these are not the symptoms of any specific deficiency

disease, but anybody can recognize the disease based

on their personal observations. Those signs can be

summarized as follows:

0018 frequent absence from school and work;

0019 lower rate of weight gain;

0020 poor appetite;

0021 dull, dry, and thin hair, which can be pulled out

easily;

0022 dry-looking face with inflammation in the nose,

lips, and mouth; fissuring at the corners of the lips;

0023 red and inflammed eyes with congested eyelids;

0024 loss of enamel and decay in teeth;

0025 pale and rough skin with pigmented patches and

scaling around the nose and ears;

0026 muscular weakness and flabby muscles;

0027 mental depression with apathetic behavior, often

showing irritability, restlessness, nervousness, or

sleeplessness;

0028 high susceptibility to infections as well as poor

wound-healing.

Pathogenesis of Deficiency Diseases

0029 It would be difficult to separate and pinpoint the

individual stages, but the pathogenesis of a deficiency

disease may be a continuous, progressive develop-

ment, which, if not interrupted at some point by

remedial action, may advance to the final full-blown

clinical picture characterizing the specific disease.

0030 This development starts with nutritional inad-

equacy because of primary or secondary deficiencies;

eventually, the body resources of the nutrients in in-

adequate supply become depleted. When tissue deple-

tion has reached a critical point, it interferes with the

normal biochemical reactions in selected tissues or in

the body at large. This will initially result in func-

tional changes such as increased fatigue or abnormal

gastrointestinal or neurologic function. As the nutri-

tional deficiency continues, minor or eventually major

anatomic lesions develop, and gross clinical signs and

symptoms become manifest.

Problem of Undernutrition or Deficiency

Diseases

0031Deficiency diseases can be grouped broadly into two

categories: one caused by vitamin deficiency and

another caused by a deficiency of other nutrients.

Disorders resulting from vitamin deficiency

0032Several important diseases in humans are caused by

the deficiency of some common vitamins, viz. vita-

mins A, C, D, thiamin, riboflavin, niacin, etc. The

names of the diseases, along with the symptoms and

methods of treatment, are detailed below:

0033Beriberi Beriberi is principally a thiamin-deficiency

disease that is quite common when pregnancy and

lactation raise the individual’s thiamin requirement,

and breast-fed infants may acquire the symptoms of

this disease, since the milky, malnourished mother

may be deficient in thiamin.

0034Important symptoms of beriberi include a loss

of appetite and disturbances in the gastrointestinal

tract. Affected individuals feel extreme weakness,

become lean and thin, develop cardiac trouble and

edema, and show mental depression, loss of memory,

anxiety, etc.

0035Because beriberi is a complex vitamin-deficiency

disease, patients make the greatest improvement

when B-complex vitamins, rather than thiamin

alone, are prescribed. The persons may also consume

a diet rich in thiamin or high in protein and calories.

0036Cheilosis and glossitis These are riboflavin-deficiency

diseases (ariboflavinosis) that are common in persons

who consume a marginal diet devoid of dairy products

or other animal protein sources and leafy vegetables.

0037Cheilosis is characterized by the appearance of

crack at the corners of the lips as well as bifurcation

at certain points. Sometimes, blood also oozes out at

those points. In the case of glossitis, small pimple-like

eruptions arise on the tongue that become red and

sometimes inflamed.

0038These diseases are treated by administration of

riboflavin coupled with an improvement in the diet.

Riboflavin supplementation should continue at the

rate of 5–10 mg daily until complete recovery. A

well-balanced diet rich in milk and milk products,

meats, and leafy vegetables should accompany the

specific vitamin therapy.

0039Keratomalacia, xerophthalmia, night blindness, and

Bitot’s spot All of these diseases are caused by a

3662 MALNUTRITION/The Problem of Malnutrition

deficiency of vitamin A (avitaminosis A) or its precur-

sors, the carotenoids in the diet. These are the most

prevalent vitamin-deficiency diseases in the world.

0040 One of the earliest signs of vitamin A deficiency is

the secretion of watery fluid from the eyes and, if

unchecked or not treated in good time, leads to

night blindness, or nyctalopia. The affected person

is unable to see well in dim light, especially when

coming into darkness from a brighter environment.

0041 The term ‘xerophthalmia’ means ‘dryness of the

eye,’ i.e., of the cornea and conjunctiva. This is

prevalent mostly in young children. The full-blown

syndrome of xerophthalmia is characterized by a

wrinkled and lusterless conjunctiva and haziness

and dryness of the cornea with small erosions or

punctate superficial infiltrations. Subsequently, per-

foration occurs, and there may be a prolapse of the

iris, or the lens may be expelled. Inflammation resem-

bling conjunctivitis may also develop.

0042 The above symptoms may lead to ‘keratomalacia,’

which is characterized by dryness and ulceration of

the cornea as well as softening and destruction of the

eyeball and blindness.

0043 In some cases, a grayish shiny spot (Bitot’s spot)

appears on the conjunctiva, which also leads to

xerosis of the cornea.

0044 Vitamin A deficiency diseases can be prevented if

carotene-rich foods are included in the diet. Treat-

ment is rapidly effective with large doses of vitamin

A, provided that the eye conditions have not become

irreversible. Massive doses of vitamin A every 3–6

months given under medical supervision have been

found to be successful in preventing high incidences

of blindness.

0045 Scurvy Scurvy results from a deficiency of vitamin C

in the diet. It is common in infants and individuals

who consume a diet devoid of fruits and vegetables,

the main sources of vitamin C.

0046 Pain, tenderness and swelling of the thighs and legs

are frequent symptoms of infantile scurvy, accompan-

ied by weight loss, fever, diarrhea, and vomiting. If

the teeth have erupted, the gums are likely to be

swollen, tender, and hemorrhagic. Scurvy in adults

results after several months of a diet devoid of ascor-

bic acid. The symptoms include swelling, infection,

bleeding of the gums (‘gingivitis’), tenderness of the

legs, anemia, and petechial hemorrhages. The teeth

may become loose and eventually may be lost. There

is degeneration of the muscle structure and of the

cartilage, with impaired wound healing.

0047 Scurvy patients respond dramatically and specific-

ally to the administration of vitamin C. The patients

can receive ascorbic acid either in synthetic form or in

the form of fresh, unheated processed orange juice of

standardized vitamin C content or in the form of

noncitrus juices enriched with vitamin C.

0048Rickets and osteomalacia These are diseases resulting

from a deficiency of vitamin D. In fact, a deficiency of

vitamin D leads to inadequate absorption of calcium

and phosphorus from the intestinal tract and to faulty

mineralization of bone and tooth structures. The in-

ability of the soft bones to withstand the stress of

weight results in skeletal deformities.

0049Premature infants are more susceptible to rickets

than full-term infants, since the growth rate and cal-

cification of the skeleton impose additional demands

for vitamin D. In early rickets, there may be few

physical findings except irritability and restlessness

during sleep. Closure of the cranial fontanelles is

delayed, and the affected infant crawls or walks late.

Softening of the skull (‘craniotabes’) and bulging or

bossing of the forehead give the head a box-like ap-

pearance. Bones become soft and fragile, leading to a

widening of the ends of the long bones, bowing of the

legs, and enlargement of the costochondral junction

with rows of knobs or beads (‘Rachitic rosary’). In

rachitic infants and children, there may be delayed

dentition and malformation of the teeth.

0050Frequently referred to as ‘adult rickets,’ osteomal-

acia literally means ‘bone softening.’ In this disease,

softening of the bones becomes so severe that the

bones of the legs, spine, thorax, and pelvis bend into

deformities. Rheumatic-type pain in the bones of the

legs is also common.

0051As long as the dietary calcium and phosphorus

intake is adequate, uncomplicated rickets may be

treated solely by administration of sufficient doses

of vitamin D. The first sign of improvement is a rise

in serum phosphorus, which is commonly observed

by the second week. This is usually followed by bone

mineralization within 2–4 weeks of initiation of

treatment.

0052Vitamin D deficiency diseases may also be pre-

vented by adequate exposure of the infants to sunlight

or by giving vitamin D in a variety of forms, such as

cod-liver oil, other fish-liver oils, or vitamin D milk.

0053Pellagra ‘Pellagra’ is a term of Italian origin, which

means ‘rough skin.’ The cause of pellagra is a severe

deficiency of niacin and its precursor, the amino acid

tryptophan. It is one of the important public health

problems in many parts of the world.

0054Pellagra involves the gastrointestinal tract, the skin,

and the nervous system. Primary symptoms include

a sore tongue, mouth, and throat, with glossitis

extending throughout the gastrointestinal tract. The

tongue and lips become abnormally red in color. The

mouth becomes so sore that it is difficult to eat and

MALNUTRITION/The Problem of Malnutrition 3663