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

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0012 Specification of the correct resins requires as much

understanding as that required by a diner choosing a

menu for a successful meal: no one would order Blue

Stilton to quench a thirst. Examples of the variations

in the nature of some synthetic resins are as follows:

0013 PUs give all-round properties resulting from their

hardness, coupled with flexibility; the surface

preparation required to avoid their delamination

has to be more scrupulous than with, for example,

acrylics; PUs possess excellent acid resistance.

0014 In general, acrylics are used for hardness and,

principally, color retention.

0015 Polyesters carried in styrene offer quick cure and

good chemical resistance to some chemicals, but

produce a strong smell during application and

need a temperature of at least 10



C to cure satis-

factorily.

0016 Epoxy types (i.e., epoxy–hardener two-pack

systems) are versatile in that the resultant proper-

ties can be varied by selection of the appropriate

hardener; they undoubtedly have excellent resist-

ance to alkalis and can be used in a solvent-free

form, but their resistance to marring and certain

chemicals is poor. (Marring is the phenomenon of

marks being left on a surface through the moving

contact of another over it. Epoxy-derived surfaces

are prone to this marring effect.)

0017 Methacrylates cure quickly and at low tempera-

tures, and exhibit rapid hardening, but during

application they give off a pungent smell which

dissipates quickly. (They are used, with special

care, extensively in Europe in food factories and

breweries.) Again, chemical resistance properties

vary with relation to specific chemicals.

The methods of curing of the above resins differ

widely, from using the moisture in the atmosphere

to requiring a peroxide catalyst (when it is known as

a free radical mechanism).

Floors

0018 There has long been a search for a floor finish that is

as near perfection as possible, and the arguments

concerning seamless surfaces and tiles have continued

for some years.

0019 In the years since 1945, seamless resin-based floor

finishes have developed considerably from small begin-

nings. Initially they were mainly to be found in the form

of clear varnishes or paints based on synthetic resins

such as alkyds and phenolics, which gave harder coat-

ings than the traditional types then available.

0020 Using resins as binders for fillers and/or aggregates

to produce polymer concretes or screeds (self-leveling

or troweled) began to be feasible with the exploitation

of the emerging technology associated with epoxy

resin chemistry. Since then, other polymers have

come to the fore in this applicational area; PUs, un-

saturated polyesters, and methacrylates are perhaps

the most prominent. The substitution of part of the

water component of a cementitious formulation with

a thermoplastic emulsion resin, in order to offer a

moderately upgraded performance over the unmodi-

fied original, yielded an economical product (so-

called polymer concrete but, more correctly,

polymer-modified concrete).

0021When there is a new development in any area, there

are usually two positive reactions amongst those who

are to specify their use. One is to resist the trend, to

adhere to the traditional methods or products and

look for examples of failures that argue for this atti-

tude. Caution is to be applauded and encouraged, but

not if it means totally resisting cost-effective improve-

ments. The opposite situation is perhaps more

frightening in that a specifier welcomes a new devel-

opment with open arms and wishes to use it at the

slightest provocation. The disastrous consequences

can be heightened by the fact that the first few instal-

lations may be successful and the next, failures.

0022It must be firmly established that no single syn-

thetic resin will offer all of the properties that will

cope with the varying in-service requirements pre-

sented to the specifier, whether it be in connection

with a new floor area or a refurbished one. For

example, the solvent resistances are quite different,

as are the resistances to specific chemicals. Physical

properties associated with impact, abrasion, elonga-

tion, and hardness also differ widely. Consideration

during application of health and safety, and particu-

larly odor, are also of considerable relevance.

0023The retardation of the rate of acceptance of all

seamless resin-based floors has been caused by high-

lighting the failures rather than the greater majority

of successes. These failures have, in the main, been

attributable to the following, and stating them will

not only be of historical interest but act as a caution-

ary and educational exercise:

0024Lack of basic understanding by specifiers of the

substance, nature, and properties of synthetic

resins and the formulated derivatives.

0025Lack of experience of many self-styled ‘specialist’

contractors in installing the systems on the one

hand, and a lack of basic understanding of this

particular medium to cope with the unexpected

on site, on the other.

0026Lack of site knowledge by certain of the formula-

tors of the systems, resulting in the systems not

being ‘workman-proof,’ but only ‘technologist-

friendly’!

2238 FACTORY CONSTRUCTION/Materials for Internal Surfaces

Indeed, in many cases the decision as to whether a

coating (measured in mm) or a screed (measured in

mm) should be laid is made without real understand-

ing and often decided purely on cost – a sure recipe

for disaster! A specific procedure for preparing the

surface to take the finish is essential.

Coatings

0027 In order simply to keep the level of dusting of

concrete down, impregnation or coating with a clear

resin is satisfactory. Acrylics, methacrylates, PUs or

epoxy types, in unmodified or clear form, give good

results. As far as impregnation or priming is con-

cerned, the variable porosity of a concrete surface

must first be taken into consideration; in this respect

just one application of the resin may not seal the

surface as, in areas of high porosity, there will be no

resin present on or at the surface. In such cases add-

itional applications have to be made until a satisfac-

tory state is arrived at; if much extra solvent-carried

medium has had to be added, the surface must be

allowed to vent before proceeding further.

0028 Clear or pigmented (paint) multicoat systems are

suitable where the substrate is smooth or of very low

profile. Antislip characteristics can be built in by

casting fine sand in an intermediate film.

0029 Perusal of trade and academic literature will pro-

vide information concerning the respective chemical

resistance of the various resin species. Various key

facts must be elicited and thence a specification

drawn up in an informed way.

Screeds

0030 If a substrate is pitted, potholed, or simply uneven,

or has special requirements, a screed is needed. By

substituting part of the water in a cementitious for-

mulation with a thermoplastic emulsion, the so-called

polymer screeds are constituted. These provide

nondusting flat surfaces of varying hardness and cer-

tainly upgrade the ‘straight’ cementitious finish.

However, they do not have the degree of chemical

and abrasion resistance often required in industry.

This is where other synthetic resins come in – epoxies,

PUs, acrylics, and methacrylates. These are now well-

known, and success is achieved by combining the

most advantageous combinations of resin and aggre-

gate (the selection of the latter plays a major part as

far as wear and antislip properties are concerned).

The main two methods of application are by trowel

or, where a formulation where self-level is used, by

pouring.

0031 One of the requirements of the food industry, as

mentioned before, is a sterile floor; in order to achieve

this, the topping must give an excellent BS 4247

rating. One method, of course, is to steam-clean or

to use virtually boiling water. Many systems, such as

epoxies, do not possess a high enough heat distortion

temperature to resist such daily treatment and, as a

result, develop hairline cracks (thermal degradation).

To some extent this can be overcome by introducing

some elasticity, but the solution is to use a medium

that does possess a high distortion point.

0032Another approach is to utilize a PU-modified con-

crete; this has been done and improvements are still

being made (Figure 1).

0033Table 1 details the characteristics of a typical

epoxy-based screed. Choosing from a wide variety

of hardeners which, with the epoxy resin itself, form

the two-pack system, a wide variation of properties

can be achieved.

0034Table 2 details the characteristics of a typical PU-

modified concrete used where high heat distortion

temperatures are required, together with excellent

physicals.

0035Table 3 proposes a scheme for the project manager

to follow when installing a resin floor.

0036Finally, one very important matter, often over-

looked, is cleaning or aftercare. The chemicals used

previously may well not be at all appropriate for the

resin-based surface, and it is the duty of the formula-

tor, through the contractor, to identify the best means

and detail it in the relevant technical data sheets. (See

Cleaning Procedures in the Factory: Types of Deter-

gent; Types of Disinfectant; Overall Approach;

Modern Systems.)

fig0001Figure 1 Polyurethane-modified concrete laid by Swansback.

Photographic Unit of the Boots Company plc.

FACTORY CONSTRUCTION/Materials for Internal Surfaces 2239

Walls

0037 Much of the reasoning and statements contained in

the Floors section of this article apply to walls. For

example, a seamless surface is usually easier to keep

sterile than a grout-containing tiled surface, although

in many situations tiles are preferable. A good

example of the latter is in the corridors of the London

Underground system where gouging and graffiti are

made very difficult by using specific and glossy tiles;

but here sterility is not a significant factor.

0038 In the food industry, as in industry as a whole, the

wall finish must resist the chemical and physical

attack of the inherent service conditions. For example,

it is quite common to steam-clean and, in such cases,

the basic resin in the finish is required to (but does not

always!) possess a sufficiently high heat distortion

temperature to resist the frequent expansions and

contractions.

0039 It has been firmly established by psychologists that

the color and texture of surroundings have a great

effect on the mental attitude of those in the vicinity.

This is not surprising when one considers the effect

the sun has on all of us when it comes out. Until 20

years ago, there was no pressure to arrange for the

decor in the fitting shop to be the same as that in the

chairman’s office. Although this attitude has changed

in essence, the desire could not be sensibly realized

owing to the technical shortcomings of available pres-

tigious wall finishes. In other words, the formulation

of multicolored and textured systems of classical or

upmarket appearance has never been a problem, but

the technical inadequacies of the systems did not

make them suitable for the more demanding service

conditions found in food industry situations.

0040Multicolored, durable, and resistant coatings have

been around for some time, but they have been paint-

like and thus of flat profile (Figure 2); in addition, the

application of more than one coat was required, thus

involving considerable labor costs. They have also

been associated during application with the unpleas-

ant smell and fire risk characteristic of solvents. This

has meant either causing aggravation amongst those

working in the vicinity, or carrying out the particular

project only when the building was totally vacated;

the suitable time for application was therefore some-

what restricted. Textured systems have often had an

upmarket appearance suitable for the chairman’s

office, but lacked the physical and chemical resistance

properties needed for more aggressive service condi-

tions, or they have had the necessary degree of resist-

ance but not the necessary classical and upmarket

appearance needed for the more prestigious sites.

tbl0001 Table 1 Typical characteristics of an epoxy concrete (filler and/

or aggregate and resin)

Characteristic Value Units

Compressive strength 55–110 N mm

2

Compressive modulus 0.5–20 kN mm

2

Flexural strength 25–50 N mm

2

Tensile strength 9–20 N mm

2

Elongation at break 0–15 %

Linear coefficient 25–30 10

per



Water absorption (7 days at 25



C) 0.1 %

Maximum service (temperature

under load)

40–80



Rate of development of strength 6–48 h at 20



tbl0002 Table 2 Typical characteristics of a polyurethane-modified

concrete

Characteristic Ucrete HF Concrete (124)

Density 2090 kg m

3

2250 kg m

3

Compressive strength 50 N m

2

27 N m

3

Elastic modules

(compression)

1200 N m

3

21 000 N m

2

Tensile strength 6 N m

2a

2.1 N m

2b

Flexural strength 14 N m

2

3.5 N m

2

Coefficient of thermal

expansion

1.5  10

per



C1.1 10

per



Thermal conductivity 1.1 W m

1

per



C 1.3 W per m per



VICAT softening point 130



Surface resistivity 3  10

O 4  10

1800 lbs in

2

300 lb m

2

(124) means 1 part cement, 2 parts sand and 4 parts aggregate.

tbl0003Table 3 Suggested scheme for managing a resin-based floor

installation

Stage effort Item

60% Evaluation

History of substrate

Past usage

Service requirements

Identification of appropriate system

and preparation

Installation constraints

Specification settled

Selection of proficient contractor

20% Installation I

(preparation of the

surface)

Contractor efficiency

Achievement of suitable surface state

Grinding, scrabbling, or shotblasting

Rectifying deficiencies

Lack of damp-proof membrane

(DPM)

Contamination

Unevenness

Slope

20% Installation II

(application of system)

Contractor efficiency

Scrupulous following of

instructions

Adequate barriers and notices

Client cooperation

Employee discipline

Using, in part, a formulated questionnaire.

2240 FACTORY CONSTRUCTION/Materials for Internal Surfaces

0041 Thus the way has been open for some time for

systems of virtually universal suitability, with

minimum hazards on application, and the ability to

provide textured or smooth finishes. These are now

gradually becoming available, especially utilizing the

properties of PU-based systems which are no longer

handicapped by yellowing on exposure to light.

0042 Within reason, what applies to floors applies to

ceilings. Thus, by using resin-based systems, a com-

plete hygienic envelope can be achieved for floor,

walls, and ceiling.

Roof Stabilization

0043 Many factories in the food industry were built before

World War II and consequently have tile roofs. These

can become unstable with the passing years. Puresin-

sprayed systems have been developed to secure and

stabilize these structures internally without complete

rebuilding.

0044 Stability and insulation are achieved through tech-

nically advanced closed-cell, rigid polyisocyanurate

(or related) foams which are tailor-made for the pur-

pose with British Board of Agre

ment (BBA) approval.

Application is by spray at right angles to the prepared

underside of tiles or slates of a roof requiring refur-

bishment. The latter procedure, coupled with a very

fast-curing or setting time, insures that foam does not

run out from between the tiles or slates and down the

outer surface of the pitched structure. Such foam has

fire-retardant qualities, passing class 1 (BS 476 part 7,

1971). Typical characteristics of the system are shown

in Table 4.

0045As with all resin-based systems, the installation

must be carried out by trained and experienced con-

tractors who can appraise the site as being suitable,

recognize and carry out the vital preparation work,

and spray the system correctly. In addition, they

should insure that the roof space is adequately venti-

lated to avoid structural deterioration through

condensation (Figure 3).

0046The foam is sprayed between (not over) the rafters

and the purlins and over the battens (i.e., on their

fig0003Figure 3 Stabilizing polyurethane Spraybond foam being

applied. Courtesy of Liquid Polymers plc.

fig0002 Figure 2 A polyurethane-based wall finish by Sempol Surfaces

Ltd in association with an epoxy seamless floor in a food factory.

tbl0004Table 4 Typical stabilizing foam properties

Property Value

Closed-cell content 90% minimum

Thermal conductivity

Initial 0.017 WMC

Aged 0.020 WMC

Water vapor transmission

10.6 mg per Nh

Service temperatures 50



Cto70



Density (overall) 42 kg cm

3

(approximate)

Tensile strength 117 kPa

Shear strength 77 kPa

Burning characteristics See text

See comments in text on roof ventilation and insulation.

25 mm thick at 30



C, 88% relative humidity.

Nh are Newton hours.

All tests results according to BS 4370.

WMC, watts per square metre per Kelvin.

FACTORY CONSTRUCTION/Materials for Internal Surfaces 2241

inside face), leaving the outer face uncoated and thus

allowing moisture evaporation. A foamed thickness

of 25 mm is preferred. Before expanding (foaming),

the liquid penetrates cracks and joints and, on curing

as a foam, bonds the slates or tiles, thus increasing the

stability of the structure chiefly against the force of

winds.

0047 In the industrial context, the duration of applica-

tion will depend on the surface area of the structure

which may, of course, be of considerable size. A single

day is all a house-sized roof will take.

0048 As already mentioned, a roof thus treated will be

sealed against wind, driven rain, and snow, i.e., storm

conditions. However, it must be noted that this will

not prevent leaks owing to cracked or displaced tiles,

slates or faulty flashings, valleys, and gutters. These

are avoided by correct, appropriate preparation of the

roof before refurbishing with the system.

0049 Being one of the best insulants commercially avail-

able, the foam, when of the order of 25 mm thick,

achieves a degree of improved insulation that should

be approximately 0.8 W m

2

per



C. Because of this,

coupled with good ventilation, the chances of conden-

sation are reduced.

0050 There are other attractions associated with this

method of refurbishment. It is carried out at a lower

cost than reroofing. The application is easy, being

from inside the roof, so that no scaffolding is re-

quired. Furthermore, there is minimum disturbance

of below-roof activity during the initial installation.

Final Comments

0051 Most problems stem from lack of knowledge of the

nature of the synthetic resin involved. Such knowl-

edge must be acquired through the medium of either

an informed contractor, fair-minded suppliers who

are prepared to say ‘you need a system based upon a

type x resin which we do not make’, or an independ-

ent resin consultant. The academic institutions can

help considerably by including far greater input on

the basic subject of synthetic resins in their syllabuses

for graduate courses in architecture, civil engineering,

and surveying.

0052 An informed, experienced, specialist contractor is

essential and can often be identified by the fact that

the company has existed for a considerable number of

years and can offer visits to past installations or, at

least, produce a substantial list of case histories and

offer good postinstallation technical service. The

basic technical knowledge referred to above is likely

to be present if the contractor formulates his or her

own systems, and is not purely a ‘menu-reader’ of

material suppliers’ literature which cannot hope to

cover all of the potentially threatening situations

arising on site.

0053For success, not only should a system based upon

the correct resin be selected, but also a good major

percentage of the effort put into the project should be

in preinstallation activity by way of full appraisal

of the site, coupled with the resultant, specifically

appropriate substrate preparation. Sadly, all too fre-

quently this is carried out after, for example, a floor

finish has failed, and only then do protimeters and the

like appear on the scene! A protimeter is an instru-

ment which measures the degree of moisture in a

surface (concrete) by means of a probe and the read-

ing on a dial of a small current of electricity which

indicates the percentage moisture. Increasing the

depth of the hole into which the probe is placed

allows moisture levels at different depths to be deter-

mined – so quantifying ‘rising damp.’

See also: Cleaning Procedures in the Factory: Types of

Detergent; Types of Disinfectant; Overall Approach;

Modern Systems

Further Reading

Jolly AC (1965) Polyurethane floor coatings. Flooring and

Finishing News 10(5): 33, 34, 37, 38.

Jolly AC (1968) Seamless flooring in the can. Cleaning and

Maintenance (4): 22, 23, 25, 26, 53.

Jolly AC (1979) A hundred years of resins. Polymer Paint

and Colour Journal 169(4001): 514, 515.

Jolly AC (1982) Seamless floors versus tiles. Polymer Paint

and Colour Journal 172(4062): 10.

Jolly AC (1985) Resin floor finishes. Architects’ Journal

181(6): 63–66.

Jolly AC (1987) Educating for change. Construction Sur-

veyor 21(64): 9, 10.

Jolly AC (1989a) Elastic, seamless roof finishing. Architects

and Surveyors Institute Journal 1(1): 29, 30.

Jolly AC (1989b) Seamless resin floors in perspective.

Building, Trade and Industry 5(4): 28, 29.

Jolly AC (1989c) Stabilising roofs using foam technology.

Dairy Industries International 54(10): 36, 37.

Jolly AC (1990a) Getting the seamless floor right. Building

and Maintenance May/June, pp. 11, 12.

Jolly AC (1990b) Are the technological advances available

being fully utilised? Building and Maintenance Sept/Oct,

pp. 7, 8.

Jolly AC (1990c) The dangers of surface knowledge. Dairy

Industries International 56(11): 25, 27.

2242 FACTORY CONSTRUCTION/Materials for Internal Surfaces

Factory Inspection See Hazard Analysis Critical Control Point

FAMINE, STARVATION, AND FASTING

E M Widdowson

and A Ashworth,LondonSchoolof

Hygiene and Tropical Medicine, London, UK

Background

0001 Despite man’s ingenuity and technological advances,

it is a sad reflection that at the start of the twenty-first

century, famine and starvation still abound, often

with such catastrophic loss of life that it can be meas-

ured in millions. Indeed, ‘food security’ has become

an industry, and ‘humanitarian assistance’ the voca-

tion of a burgeoning number of organizations who do

nothing else. It is a damning indictment of our times

that when the medical relief organization Me

decins

Sans Frontie

res was awarded the Nobel Peace Prize,

they were working in over 80 countries.

0002 We shall examine the causes of famine and starva-

tion, both past and present, and some of the physio-

logical changes that have important consequences for

those looking after the afflicted. We shall also look

at fasting and starvation in the midst of plenty, in

particular anorexia nervosa and bulimia.

Causes and Effects of Famine

0003 Famine can be defined as a prolonged scarcity of food

causing many in a district or country to die from

starvation and/or disease. In communities dependent

on subsistence farming, ‘hungry seasons’ are not

uncommon, but coping strategies exist to mitigate

the adverse effects and insure survival. For example,

nonessential items may be sold and debts called in,

and there may be greater use of wild foods. What

distinguishes ‘famine’ from ‘hunger’ is that in famine,

the usual coping strategies are insufficient. Thus

famines are characteristically accompanied by ex-

treme measures that may disrupt future livelihoods,

for example, the selling of animals, land, and other

essential items. In a famine, families are often driven

to eat unconventional items, such as rodents, beetles,

worms, roots, leaves, bark, grass, candles, and leather.

0004 Famines have occurred from time to time through-

out history, and there are many records of them in

early writings, such as the Bible. In general, they were

caused by crop failure due to droughts, floods or

pestilence (e.g., locusts, blight). In Europe in the

Middle Ages, they were often accompanied by out-

breaks of typhus, cholera, typhoid, dysentery, small-

pox, measles, and scarlet fever, and famine led to their

spread and severity. In more recent times, misguided

political gambits have caused disastrous food short-

ages, as witnessed by the famines in the former Soviet

Union and China, where privately owned small farms

were merged into collectives and crops procured by

the State to provide the wealth to support industrial-

ization. Some 30 million people are estimated to have

starved to death in China during Chairman Mao’s

Great Leap Forward.

0005Starvation may be used as a political tactic and

knowingly engineered (as in the internment camps

of Belsen). Incongruously, countries gripped by

famine often continue to export staple food crops,

as was the case in the Irish famine of the 1840s and

more recently in the famines in Ethiopia and Sudan.

Mass movements of populations in search of food or

fleeing from conflict situations have become com-

monplace on our television screens. Tented camps

and humanitarian aid may be a refuge from starva-

tion, but thousands of people with weakened immune

systems living in close proximity are vulnerable to

epidemic diseases, and many die as a result. Table 1

shows some of the twentieth century famines and the

estimated number of deaths.

0006Increasingly, famines are linked with ineffective

political structures, armed conflicts, environmental

degradation, and ethnic or religious unrest emanating

from disregard of civil and human rights. The effects

are wide-ranging. The use of land mines, for example,

limits access to local markets and hampers food relief

efforts in the short term, but also continues to kill,

maim, and disrupt agricultural production in the

long term, as seen in Mozambique, Angola, and

Somalia. Forced conscription of young men for

combat adversely affects food production and food

security in rural areas, and arms purchases divert

foreign exchange from already under-resourced

health and development budgets and deter inward

economic investment. Evidence of the effects of

climate change can be seen in unusually prolonged

periods of low rainfall at one extreme and increased

Deceased.

FAMINE, STARVATION, AND FASTING 2243

frequency of hurricanes and floods at the other. These

wreak havoc to crops and livelihoods, decrease soil

fertility, increase erosion, desertification and salina-

tion, and disrupt transport routes. These factors,

however, are associated with famine only where

populations are chronically poor. Hence, combating

poverty is a major concern in famine prevention and

mitigation.

Structural and Physiological

Consequences of Undernutrition and

Starvation

0007 Starvation implies that little or no food is eaten.

Undernutrition arises when some food is eaten, but

the amount is insufficient to meet physiological and

metabolic requirements. In many ways, the effects

of starvation and undernutrition are the same, and

the differences are those of degree. It goes without

saying that a starving or undernourished person loses

weight, but the organs and tissues lose weight at

different rates. The least essential tissues suffer first;

hence, adipose tissue is mobilized and the fat oxidized

to provide the energy necessary for the metabolic

processes that must go on if life is to be preserved.

0008 Some loss of nitrogen is inevitable despite the in-

creased production of free fatty acids, and this comes,

to a large extent, from the proteins of skeletal muscle,

leading to shrinkage of the muscle fibers. The break-

down of muscle proteins provides the amino acids

alanine and glutamine, whose carbon skeleton can

be used to make glucose. The skin also loses protein,

both structural and cellular, and becomes thin and

easily infected. The loss of its protein, together with

the loss of subcutaneous fat, makes the skin hang

loosely on the bones.

0009The internal organs lose weight, the liver some-

times a great deal. In edematous malnutrition, how-

ever, the liver may increase in weight by as much as

50% owing to the accumulation of fat, which is

caused, at least in part, by a reduced synthesis of

lipoproteins that transport triglycerides out of the

liver and into plasma. The alimentary tract loses

weight and becomes thin, and there are marked

changes in the gut mucosa, especially the villi, which

become flattened and broader, and have reduced

levels of digestive enzymes. The heart and kidneys

tend to lose weight in parallel with the body, and

their function is impaired. The brain is preferentially

protected, although there is a reduced density of

neuronal synapses and dendrites.

0010Healthy, well-nourished individuals operate with

considerable ‘spare capacity.’ Thus, our bodies are

able to respond when we run very fast or eat a very

large meal. This excess capacity, however, is ex-

pensive to maintain, and when food intakes are

insufficient, it is reduced to conserve energy. This

‘down-sizing’ of the body’s functional capacity affects

every system, organ, and cell, and is termed ‘reductive

adaptation’ (see Figure 1). One example of reductive

adaptation is the slowing down of the sodium pump

in cell membranes. The purpose of this pumping

activity is to maintain the correct concentration gra-

dient, and it normally accounts for about one-third

tbl0001 Table 1 Selected twentieth century famines.

Year Location Number of deaths Notes

1899–1900 India 1 million Drought

1915–1918 Germany 200 000 War

1918–19 Uganda 4 400

1920–21 North China 500 000 Drought

1921–22 Russia, Ukraine and Volga region 1.3–5 million Drought

1928–29 China, Shensi, Honan, and Kansu 3 million

1932–33 Russia 3–10 million Collectivization

1941–43 Greece 450 000 War

1941–44 Leningrad 1 million War

1941–42 Poland, Warsaw 43 000 War

1943 Ruanda-Urundi 35 000–50 000

1943–47 India, Bengal 3 million Drought and war

1958–62 China 30 million Collectivization and natural disasters

1967 India, Bihar Relief operations mitigated the effects of

the disaster

Drought

1971–73 Ethiopia 1.5 million Drought

1988 Sudan 250 000 in Bahr El Ghazal War

1998 Sudan 60 000 War

Adapted from Alamgir M (1981) An approach towards a theory of famine. In: Robson JRK (ed) Famine: Its Causes, Effects and Management. London:

Gordon and Breach Science and Watson F (1999) One hundred years of famine – a pause for reflection. Field Exchange Issue 8: 20–23.

2244 FAMINE, STARVATION, AND FASTING

of the basal energy expenditure. Although energy-

sparing, this slower pump rate is not entirely benefi-

cial, as it allows sodium to accumulate inside cells and

potassium to be lost, thus contributing to potassium

deficiency. There are several serious consequences of

potassium deficiency, including fluid retention and

edema, and impaired cardiac function. Other func-

tional changes in starvation include a slower heart

rate, reduced ability of the kidneys to excrete excess

sodium and excess fluid, which increases the risk of

heart failure, and reduced ability to make glucose,

increasing the risk of hypoglycemia and hypothermia.

Thus, there are both positive and negative conse-

quences of ‘reductive adaptation’.

0011 The resting metabolic rate per kilogram body-

weight is not greatly reduced in moderate undernutri-

tion, but in a starving person, it ultimately falls, as

does body temperature. In moderate undernutrition,

the digestive tract functions normally, provided there

is no infection, but in a starving person, diarrhea may

become severe. This has been attributed, at least in

part, to the colonization of the normally sterile upper

intestine with bacteria, which then produce toxins,

damaging the gut mucosa and increasing fluid

secretion into the gut. The dehydration resulting

from this may prove fatal. In addition, some of these

bacteria deconjugate bile salts, reducing the body’s

ability to absorb fat.

0012The survival time of an adult who takes no food

depends upon the availability of clean water. If plenty

of water is available, a previously well-nourished

adult can survive without any food for about 60

days – the exact time depending partly on the amount

of fat in the body. Starving or near-starving infants

and young children are in a far worse plight, particu-

larly if they are also short of water, because their

requirements for energy and water per kilogram

bodyweight are greater than those of adults.

0013Extreme wasting occurs among hospitalized

patients, the causes varying with the nature of the

disease or type of trauma. Some conditions, including

cancer, markedly depress the appetite leading to semi-

starvation as a result of low food intake. Some condi-

tions lead to actual loss of nutrients, for example

gastrointestinal diseases and postoperative drainage.

Injury and infections trigger an increased demand

for nutrients to fuel the immune response, including

amino acids for the synthesis of acute phase proteins.

These are derived from muscle protein breakdown,

causing wasting. Malnutrition in hospital, however, is

also often the result of prolonged underfeeding due to

inadequate or inappropriate nutritional support.

Even in affluent countries, as many as 50% of hospi-

talized patients are malnourished.

Refeeding after Undernutrition and

Starvation

0014When World War II ended in Europe in May 1945,

several groups of doctors and nutritionists went to the

liberated camps to supervise the feeding of the starv-

ing inmates. It was generally believed that the digest-

ive tract would not be able to tolerate food for some

time, and that intravenous feeding would be neces-

sary in the early stages. This proved not to be true.

The previously starving men had good appetites and

took very large amounts of food (25–42 MJ, 6000–

10 000 kcal per day). They gained about 10 kg in 6

weeks, and the response was similar in young and old

men. The same is true for severely malnourished chil-

dren. After a few days of treatment, they become very

hungry and will double their food intake and gain

weight very rapidly. After a few weeks, when their

weight deficit has been corrected and they approach a

normal weight for their height, their appetites and

food intakes revert back to levels appropriate for

well-nourished children of a similar size.

0015The physiological and metabolic changes that occur

in starvation have to be taken into consideration

Anorexia

Loss Deficiency

Infection

Reduced intake

Starvation Malabsorption Neoplasm

Reduced mass

Infection

Small bowel

overgrowth

Losses

Specific

deficiency

Reduced work

Loss of reserve

tissue and

functional capacity

LOSS OF HOMEOSTASIS

Body composition

changed

Physiological and metabolic

responses changed

Efficient use

Reduced requirement

fig0001 Figure 1 Schema showing the changes that occur in severe

malnutrition. When malnutrition is prolonged, the adaptive

changes are insufficient to maintain homeostasis. Reproduced

with permission of Oxford University Press from Golden MNH

(1996) Severe Malnutrition. In: Weatherall DJ, Ledingham JGG

and Warrell DA (eds) Oxford Textbook of Medicine, Vol. 1.

FAMINE, STARVATION, AND FASTING 2245

during refeeding, otherwise death from cardiac fail-

ure, infection, hypoglycemia, and hypothermia are

likely. Treatment is considered in two main phases:

a short stabilization period to treat infections and

correct the main metabolic disturbances (e.g., fluid

and electrolyte imbalance, and micronutrient defi-

ciencies) and a longer rehabilitation period to replace

lost tissues. Many humanitarian aid agencies looking

after starving populations have a very organized

system of identifying those who are severely malnour-

ished so they can prioritize them for supervised refeed-

ing. Aid agencies often use food preparations that have

been specifically formulated for severe malnutrition to

provide the correct amounts of energy, protein, potas-

sium, magnesium, and micronutrients. In hospitals

and nutrition rehabilitation centers, suitable prepar-

ations can be made from milk, sugar, oil, and an

electrolyte/mineral mix, and/or modified local foods.

0016 The essential characteristics of successful dietary

treatment in the stabilization phase are small, fre-

quent feeds day and night that provide just enough

energy and protein to meet maintenance needs. This

will halt any further loss of tissue and, together with

provision of potassium, magnesium, and micro-

nutrients, will restore normal functioning of the

deranged metabolic machinery. In the rehabilitation

phase, the aim is to restore the lost tissues. This

involves providing large amounts of the nutrients

that provide the building blocks for tissue synthesis,

and high energy intakes to cover the energy cost.

Thus, the aim in this phase of rapid catch-up growth

is to encourage children to eat as much as possible

and to provide them with diets that are high in energy

and protein, whilst continuing to give extra potas-

sium, magnesium, and micronutrients.

Fetal Undernutrition

0017 The question sometimes arises as to whether an infant

born small for its gestational age because of under-

nutrition before birth will remain small. This is diffi-

cult to answer because the genetic make-up of human

individuals is so diverse, and genes, as well as nutri-

tion, influence the rate of growth. Animal studies

with pure-bred strains provide some information.

The ‘runt’ pig, born much smaller than its littermates,

is unlikely to catch up to its larger siblings, and rats

that are born very immature, when undernourished

during the suckling period, take less food after

weaning and remain small for the rest of their lives.

There is some evidence that this is also true for small

newborns in developing countries, especially if their

smallness is because they are short in length, rather

than thin. It is difficult, however, to separate the effect

of fetal undernutrition from the growth-limiting

effects of being raised in the same environment that

detrimentally affected fetal growth. Interestingly, no

long-term effects on adult size were found in those

individuals whose mothers suffered 6 months of star-

vation in the Dutch famine of 1944–45 but then were

raised with a good standard of living. There seems

little doubt, however, that the earlier undernutrition

is imposed, the more likely it is that the effect will be

permanent. Barker and colleagues have suggested

that retarded growth of the developing fetus is asso-

ciated with a number of chronic conditions in adult-

hood, including diabetes, hypertension, and ischemic

heart disease.

Role of Fasting in Health and Disease

0018Some people fast even when they are healthy and

there is plenty of food available. The reason may be

political: thus, ‘hunger strikes’ are used by political

prisoners and others from time to time to draw atten-

tion to their cause. Some fast for religious reasons.

Religious fasting is usually of a short duration. Ram-

adan, for example, held in the ninth month of the

Muslim year, involves going without food or drink

between sunrise and sunset for the month. This short

period of abstinence is likely to do little harm, and in

any case, those who might be injured by it (e.g.,

pregnant women) are exempt from the fast.

0019A more serious problem is anorexia nervosa. This

is a psychiatric eating disorder that tends to run in

families and appears to be increasing in prevalence.

The sufferers, usually adolescent girls and young

women, are obsessed with the idea that they are too

fat, and that they must lose weight and remain very

thin. They may have been overweight in the past, but

not necessarily so. They often come from better-off

homes, where there is no shortage of food. Long-

standing cases may repress the sensation of hunger,

but for others, the sensation persists, and so the term

‘anorexia’ is misleading. Sometimes, the desire for

food overcomes them; they eat a great deal and then

deliberately induce vomiting; this condition is called

bulimia. Or they may resort to laxatives and diuretics.

The effects of insufficient food are the same as those

already described, and death from starvation is not

unknown. One of the symptoms is often amenorrhea.

This is also characteristic of ballet dancers and gym-

nasts who deliberately eat too little food in order to

maintain an acceptable size and shape. (See Anorexia

Nervosa; Bulimia Nervosa.)

0020If the patient with anorexia nervosa can be per-

suaded to take more food, which is not easy, then

physical recovery and restoration of weight take

place just as in others who have starved and then

been refed.

2246 FAMINE, STARVATION, AND FASTING

See also: Anorexia Nervosa; Bulimia Nervosa