Assessment of energy intake

Assessment of energy intake Estimates of food supply v measurement of food consumption

Elizabeth A. Dowler and Young Ok Seo

Nabonal consumption Indicators are frequently compiled using food supply estimates in the absence of reliable household or individual Intake data The authors examine the relationship between these three levels of mformation and in particular, the potential ‘losses’ of energy in the food system, comparing data from different countries’ and over time They demonstrate the unreliability of supply estimates as proxy indicators of consumption and quesbon their current usage in statements about global hunger and the links between health and food intake

The assessment of tood energv supply. whether at the mdlvldual. the h ousehold or natlonal level. 1s a major preoccupdtlon of mstltutes and agencies concerned with food and agriculture The purpose m mterpretIn_ethe data ~arles from predIctIon ot future movements m foodstuffs to

Keywords UK National Food Food supply, Food wastage

Larlous countries

Survey

E A Dowler IS with the Nutntlon Policy Unit, Department of Human Nutrition, London School of Hygiene and Tropical Medlclne, Keppel Street, London WClE 7HT, UK Dr Young Ok Seo was formally with the Nutrition Policy Unit and IS now working with the Korean Rural Nutrition Institute, 88-2 Suh Doon Dong Suwon. Kyung KI Province. Seoul, Korea Both authors are Indebted to PhIlIp Payne (Head of the Nutrition Department) for his continual support and advice throughout this work and to Professor T T Poleman of Cornell University for his comments on this paper Views expressed here are entirely thelr own ‘World Bank, World Tables. second edltlon. Johns Hopkins University Press, BaltConfrnued on page 279

278

attempts to assess nutrient Intake adequacv The reasons for the latter exercise depend to some extent on who IS makme the measurements national

lnstltutlons

agricultural

mdv

he concerned

and health sectors

consumption

with

pohcles

m the

food.

and wish to develop Indicators based on

data both to monitor Ttatus In whole populations

and serve

as warnings tor Interkentlon InternatIonal agencies. on the other hand. as well ds provldlng technical back up for such local actl\ltle3 often become

Involved

In publlshmg lntormatlon

series of social and economic

data on

on food supplq’ IS almost always included

otten under the heading of heAh or social Indicators Calorie suppI> per cdplta 15 that most otten quoted These figures usually derive from the FAO Prorllrcttor~ Yeurbooh When the data are presented as a percentage of requirements ’ the requirement figures are usually those published bv the FAO or WHO Such series ot data ‘Ire used both to mahe cross-country comparisons ‘md to follow trend\ over time HoHe\er this exercise In mahlng comparisons IS sometlmes further

than complllng

lists There

are instances where

tahen

the per capita

the lnequahtles ot calorie supplv figures dre used to emphasize consumption hetween countries - ,Ind even to support accusations ot Indulgent behablour (such as o\erconsumptlon and wastage) on the part ot the populations of richer countries ’ National average suppI> figures are also used In attempt? to estimate numbers malnourished m a particular region or the world as a whole, that IS. those whose consumption falls short ot requirements ’ Furthermore. the size of the gap - b! how much In aggregate. lntahes are below requirement - IS used as a measure ot the Increases In agricultural production needed to provide the necessary tood Several ,luthors habe questioned

0306-9192/85/030278-l

the theoretlcal

1$3 00 Q 1985 Butterworth

basis of the various

& Co (Publishers)

Ltd

-tssr,wwt1r OJ mrrg\ calculations

described

determInIng

energy

concept

filed

of

constitutes rlateness

of

seem Conbnued from page 278 Imore, UD, USA, 1980, FAO, Stale of Food and Agrrculture 1980, FAO, Rome, 1981 ‘D S Miller, Man s demand for energy, In K L Blaxter. ed, food Charns and Human Nutnbon, Applied Science Publishers Barklng UK, 1979 3FA0, The Fourth World Food Survey, FAO, Rome, 1977, S Reutllnger and M Selowsky, Malnutnbon and Poverty, World Bank Staff Occasional Paper No 23, Johns Hopkins University Press, Baltimore, MD USA, 1976 4P R Payne, Review of Malnutntlon and Poverty, Food PO/ICY, Vol 2, No 2, May 1977, pp 164-165 and Letter to the editor’, Vol 2. No 4 November 1977, pp 352-354, T T Poleman, A reappraisal of the extent of world hunger, Food PO/ICY, Vol6, No 4. November 1981, pp 236-252, P V Sukhatme and S Margen, Autoregulatory homestatic nature of energy balance , Amencan Journal of C//meal Nubt/on Vol 35. 1982, pp 355-365, TN malnutrition Measuring Snnivasan. Ceres, Vol 16 No 92, 1983. pp 23-27 M Lipton, Poverty, Undemutntron and Hunger, World Bank Staff Working Paper No 597, 1983

fact

requirements)

le use supply

and

the

data as intake

to contend

from national

suspect.

and

dlfftculty

diet Many comment whtch treat supply

calculations

to be grounds

derived

the problem ot ’ They discuss at length (and In particular the vahdlty of the

aboLe

requirements

an msufflclent

consumption

lrlruhr

food

thus

that

data

(Food

calculations

ot

defmmg

Hhat

on the mappropas rf they were

measurements

measurements

supply

that

of

briefly data

There would which are Sheets) are m

of Intake

Balance numbers

malnounshed.

adequacy of foodstocks and gaps’ and all the trend dnd ranking analyses In terms ot consumption which are based on these supply data, must be suspect

too

The food system There IS a deceptl\ely can be said to operate. Food

supply

simple series of levels namely Food

d\ailable

at national

level

Obviously level which

thrs system can be dmplifled contribute to the downward

+

household

dt bhlch

Food

dt

the tood

system

consumed

---) b\ lndlvldual

level

to Include subsectors at each flow (tor example food can be

grown or redred wlthm the country imported reledsed from storage) and cross linkages of markets which complicate the simple notion of movement

from producer

to consumer

For example

a household

can

grow Its own food, buy food on the market. recel\e tood as a image or exchange food as a gift with other households Figure 1 sho\is a stralghtformard point

out.

example the

of such dl\erslhcatlon

measurement

of

tood

Thus. as Burk and Pao

consumption

has

d different

ImtINtlons md

eatmgplacss.

Household usa m meals aacks.etc

Figure 1 The food system Source

flow of food from producer

to consumer

Modlfled from Burke and Pao, op cut, Ref 5

FOOD POLICY August

1985

279

4ssr,sr~lellr

01

errcrq\

rtmhc

‘M C Burk and E M Pao, Methodology for large-scale Surveys of Household and /nd/ndua/ f3efs. USDA Agncultural Research Semce, Home Eionomlcs Research Report, No 40 6There IS a wide literature on the technlcal and theorehcal issues involved In measuring an indivtdual s normal food Intake P V Sckhatme, The world s hunger and future needs In food supplles , Journal of Royal Sfafrsf/ca/ Socrefy America, Vol 124, 1961, pp 463, (one among many wntlngs by Sukhatme on the subject), J W Marr, lndlvldual dietary surveys Purposes and methods’, World Renew of Nufrrfron and Dlefefrcs, Vol 13, 1971, pp 105-l 64, G H

Beaton, J Mllner, P P Corey, V McGuwe. M Cousins, E Stewart M de Ramos, D Hernlt, P V Grambsch. N Kassins and J A Little, Sources of variance in 24-hr dietaryrecall data lmplicatlonsfor nutrition study design and interpretation 1Amencan Journal of C//nrca/ Nufrrbon, Vol 32, 1979, pp 2546-2559, K J Acheson. I T Campbell, 0 G Edholm, D S Miller and M J Stock. The measurement of food and energy Intake in man - an evaluation of some technaues’. Amencan Journal of C//nrca/ Nufnfion. Vol 33, pp 1147-l 154, E F Wheeler. Food con&mption surveys’, In J S Weiner and J A Laurie, eds, Pracflcal Human Bology. Academic Press, London, 1982, A Fei;o-Luzzl, Meaning and constraints of energy-Intake studies in free-lmng populabons , In ed. G A Harnson, Energy and Effort. Symposia of the Socrefy for the Sfudy of Human Bology Vol XXII, 1982 Taylor and Francis. London, 1982, J E Stuff C Garza E O’Bnan Smith B L Nichols and C M Montandan. A comparison of dietary methods in nutritlonal &dies’, Amerrcan Journal of Clmfca/ Nufrrf/on. Vol 37, 1983 pp 300-306, K S Todd, M Hudes and D H Calloway Food Intake measurement problems and approaches , Amerrcan Journal of C/fn/cal Nufnfron. Vol 37, 1983, pp 139-146, J

unpllcatlon

m different

consumption

parts of the system. and the concept

itself vanes wth

I&r bwilral iilefar\-

of the researcher

ot tood ’

sw ise\ s

Interest IS usuallg tocused at the right-hdnd end ot the tood system. dt the lndlwdual level and on Indl\ Idual dietdrv sune!,s hledsurlng energ! dnd nutrient

Intakes of Indl\lduals

with an> preclslon

~hlch

record all food eaten o\er several davs ‘Such

costly

In

time.

u hat a pxtlcular

measure

period Intake

le the drnount that might be called the true . normal Intahe

there

are

weighing

dnd

behdl lour Intahe no\elt\

mrthodolo~lcdl

Ingredients

Direct obsendtion of meals dnd Ilksl! to cause abnormal

problems

IS verb Intruwe

The more rxeclselv dn dttsmnt IS made to measure the actual the

behd\lourdl

less lIkeI>

It

IS this

dcconimoddtion

mdg

represents

incredse

the

in some

ot being \\atchrd

ot the experience

nlternatl\e Imolvlng

normal

Indeed

circumstances

ds the

and measured Hears ott The

to weighing and measurmg IS to use questionnaire techniques memory or estimates ot portion we. these are generalI\

considered

The

dre

HoHe\er. if the nlm IS to obtam an estimate of the hdbitual of food dnd nutrients tar &I particular Indl\ldual or group ot

indiwdudls then

requires sur\eJs

measurements

and money It IS nonetheless possrble to mdl\ldual has eaten o\er a nartlcular time

motl\atlon

to glie

unreliable

IlteratureL’on

food Intake

IS Important

research

mlphed

or

ot

true

dlfflcultles

Intakes’

In Indl\lduals

of measuring

because so many questlons.

whether

In pol~cv Issues, seem to hinge

much toad particular hnow about

estimates

these technlc,ll

Intakes

people are customarily

ot Indl\ldual

people

posed In

on hnowng c horn

edtlng

wIthIn

-

Indl\ldual

It IS necessary to

particular

populations

to

understdnd ISSLIZS ot glob‘~l hunger and mdlnutrmon - how this problem IS detlned and the Impllcatlons of the numbers ot people - and tor epldemlologlcal

Involved

studies ot the Imh beween

Intake ot

energ\ and nutrients trom Particular sources dnd Ldrious malor , LdlseJses In other \\ords there IS a need tor lndlc‘jtors of consumption that dllon d problem to be defined in terms ot mdgnitude dnd numbers of

people

’

lndlcators

and

’

to

predict

future

I_!nfortun;ltel\

Mullen. N J Krantzler. L E Grwettl M G

The suneys

Schulz’ H L Melselmai, Validity of a food frequency queshonnalre for the determination of Individual food intake , Amerrcan Journal Cfrnrcal Nufnhon, Vol 39 1984, pp 136-l 43 ‘Marr, Beaton ef al. Ferro-Luzzl, Stufi ef al Todd et al, rbrd, M Baloqh. H A Kahn and J M Medalie, Random repot-l 24-hour dietary recall , Amencan Journal of Clrnrcaf Nuhffon. Vol 24, 19711 pp 304-310 A Lechtlg C Yarbrough, fi- Marlorell. H Delaado and R E Klein. The one-dav recill dietary survey a review of its usefuiness to estimate protein and calone inArchwos Lafmo-amencanos de take’, Nufrrcron, Vol 26, 1976, pp 243-271 Both Ferro-Luzzi and Todd ef al discuss ways of ImprovIng the estimate of an lndlvidual s usual Intake by increasing the number of days measured Both suggest that by measuring one-day Intakes for five to SIXdays, the estimate can be brought to wIthin 10% of the true Intake with 95% Conbnued on page 28 1

neYt lekel up on Figure

280

the objectlkes

thdt hais

the heen

done

COIISW~~~IOIIslit I ~\~s

Household

intdke

Indl\lduals

measurements ’

dre

ot

changes

1s generally

\er!

otten

In

those

not a\allable

measurement\

at the

1 the household

HIM-ehold about

consequences

lntormatlon

Techniques

bl detlnltlon \drj

from

do not reveal anything

\\el_ghlng

or

documentmg

Intakes ot meals to diary recording and r&zall Intervle\\s Food eaten outside the home. and the presence of non-household members during measurement are sometimes recorded and ‘adjustments made Many of the technical problems (accurxq Lersus lntruslon sample size. repetition rates and so on) are slmllar to those of Indl\ldual dietar! surveys ’ Some are lntrlnslc to household studies -such a\ what constitutes a household’ and ho\\ to avoid double counting where food IS prepared m more than one kitchen or eaten In chdnges

in larder

stocks.

or NeIghed

more than one unit ‘) Further sources of error In Household

Consumption

Surveys (HCS)

Include potential sampling bias In selectlon of households and m time I” In mdnv places toad suppI!, or usage may be quantltatlcely dnd qualltatlvelv hlghlv dependent on season for some or all of the

FOOD

POLICY

August

1985

populations

concerned.

fact of course. regardless

and for some or all of the food consumed

most natlonal

of seasonal

surveys are carried on throughout

factors.

though

some puhhshed

In

the year

analyses may

Indicate their effects (In some circumstances these seasonal factors may become so marked as to alter sample accesslblhty Where this IS the becomes more speculative. especially ds this case, mterpretatlon problem IS often the most elusive to remedy ) A mean Intake expressed as for a whole year may Indicate actual Intakes for a particular group at any one time and therefore would not be representative of true Intakes of the

whole

potential Continued from page 280 confidence Thereafter, little Improvement of the estimate occurs with addItional days measured ‘For dIscussIon of methodology of household dietary surveys see Burk and Pao, op at, Ref 5 and Wheeler, op cit. Ref 6 ‘Wheeler, op c/t, Ref 6, M T Martin. MSc thesis, food fntake m hrvo Bambara V/f/ages m Ihe Segoo region of Ma//, Department of Human Nutntlon, London School of Hygiene and Troprcal Medicine, University of London, London, 1982, D J Casley and D A Lury, Data Coflecfron m Developrng Countrfes, Oxford University Press, Oxford, UK 1981 ‘°Casley and Lury. /b/d “The UK National Food Survey (NFS) publishes quarterly and annual results by factors such as geographical area, household size, occupational class, and by other factors of Interest such as age of housewife, ownership of freezers ‘*For a dlscussion of how the NFS allows for wastage and losses MAFF Household Food Consumption and Expenditure 1980 With a Review of 1975-1980, Annual Report of the National Food Survey Committee (NFS), HMSO, London, 1982, also 1981 Report ‘3E A Dowler, A pilot survey of domestic food wastage , JoJrnal of Human Nutrition, Vol 31. 1977. DCJ171, R W Wenlock and D H Buss W&age of edible food In the home a prelimin&y study’. Journal of Human Nutrition. Vol 31, 1977, pp 405, R W Wenlock, D H Buss and B J Deny, Household food wastage in Britain’, &itrsh Journal of Nutnbon. Vol 43, 1980, pp 53 141b/d 15E P Cathcari and A M T Murray, A note on the percentage loss of calories as waste In ordinary mixed diets’, Journal of Hygiene, Vol 39, 1939, pp 45, Studies on food wastage In the USA Include S F Adelson. E Asp and I Noble, Household records of foods used and discarded’. Journal of the American Defebc Assoaaf/on, Vol 39, 1961, pp 578. C G Harrison. W L Rathfe and W W Hughes, Food waste behaviour In an urban populabon’, Journal of Nutntron Educatron, Vol7,1975, pp 13 M V Zaehnnger and J 0 Early, Proceedings of National Food Loss Conference, University of Idaho, Boise, ID. USA, 1976

FOOD

POLICY

August

1985

time

period

Such means are also unlikely

problem periods for any particular

group

to Indicate

nor would

variations

from one year to the next necessarily show up even If the surveys themselves were annual In all circumstances. the potential use of natlonal

HCS

population a glken

to detect and predict

problems

of food Intake

over time will depend on the particular

country

theoretical

-

and

account

how

closely

In published

the

results

methodology

survey

practice

Few authors

within

a

used In

follows

the

discuss this Issue.

nonetheless, the potential for HCS to represent actual mean Intakes IS there. not least In that results can be dlsaggregated by geography and time

Intakes

obtained I’ A potential

of

particular

source

groups

of error

of

Interest.

In national

bv

HCS

season

which

can

be

has recently

attracted particular attention In parts of Europe and the USA IS the Issue of domestic food waste and losses In fact few accounts have been published

of small-

or large-scale

surveys

of mastage

at the domestic

level In most national surveys a somewhat arbitrary allowance IS made for wastage. In the UK for Instance when the estimates of consumption comerted

to energy

recommended

and

Intakes.

nutrients

are

a 10% reduction

expressed IS made

as percentages

to allow

for plate

of and

kitchen wastage. spoilage and feeding to pets’ ” A Food Waste Survey LJmt was set up In the UK by the MInIstry of Agriculture, Fisheries and Food (MAFF) In 1976 wlthm the National Food Survey It concentrated Its mqulr! with a particular concern for measuring

on the domestic tood tor human

level at tlrst. consumptron

fed to animals I3 Two pilot surveys and a national surbey were conducted to collect all food Intended for human consumption but not actually eaten o\er one week The energy protein and fat content of this wastage

was measured

and presented

as a proportion

of the energy

recorded as entering the household over the same perrod were done at different times ot the year and on dlfterent

” The sur\eys sample sizes.

nonetheless

only

the results

were

consistent

and showed

that

-l-6”.

of

potential food energy was discarded This result compares well with that of a UK surbe! In the 1930s of 2-3’4~ and with those available from the USA of about 7% ” Further

technical

errors

m HCS can occur when

recorded

Intakes

are

translated into nutrients and calories by means of local extraction rates and food tables, these sources of error are possibly those most amenable to regular

momtormg

Several throughout

countries carry out regular sample surveys of food Intakes the nation, using the household as the consuming unit desptte the mtrrnslc appeal of the prmclple of measuring of food actually consumed by the household - errors and

However, quantltles

uncertamties consumption

and potential

ellmlnatlon

notwlthstandmgmany countries do not mount household surveys at all, or only at irregular Intervals Thus, the

source ot InformatIon about Intakes m these countries even further back on the aggregation scale m Figure food

supply

Nlltlonal

or food

toad

balance

halunce

has been the lebel 1 th,~t ot natlondl

sheets (FBS)

sheets

Food balance sheets (FBS) are compiled regularly In man! countrtes to give a ‘comprehenwe picture of a country \ food wpply durln_r d specified

reference

Imports

and exports

for seed

animal

” Account IS taken of productlon ‘md stock changes for dll tood productlon.

period feed.

manufacture

storage aldlldble

and transport subtracted tor human consumption

decades

of eftort

It

sizes m estimates

IS

for non-toad

use dnd losses during

The residual IS tdken to dt the retail level Despite

still admitted

occur

ewmates H Ith uses

that errors

throughout

of kno\\n

the system

be th,u several

and unhnown

for reasons

discussed

else\\ here I7 and that these errors are therefore compounded In the tl_rures d\allable for human consumption Several authors suggest that the technques systematically underestimate the amount a\allable tar consumption

m less developed

countries

concerned “( The food a\dtlable tor consumption cdplta hms. tor \\hlch use IS made mid-Jeer

estimates

of

populdtlon

partIcularI\

\\here

IS

energy

IF

usuallv presented on a dally per ot the LJN Populatton DI\lslon

we

(These

estimates

allo\\

for

lmmlgrdnts tourists and special groups such ds retugee camp occupants, but nonetheless contain their own Sources ot error ) Food IS expressed In terms

of

Indl\ldual

commodltles.

dnd

ot

calories

and

nutrients

obtained from those commodltles bj reference to detdlled specifications ot each foodstuff (such as water content, mllllng extraction rates) and use of regional FAO Food Composition Tables Each of these stages Introduces further some extent the

errors. degree

another

time.

and over

some of which can be quantified However of ImprecIsIon varies trom one country so that generalizations

ments are dtfflcult to mahe The FAO publlcatlons all 16For descn@on of the construction of food balance sheets, FAO, Food balance sheets 1975-77 average and per caput food supplies 1961-65 average 1967-77 , FAO. Rome, 1980, for dIscussion of the and problems, PV methodology Sukhatme, op nl, Ref 6, FAO, Provisional food balance sheets’. FAO Rome. 1977. @leman. op crt, Ref 4 ’ ‘Ibrd ‘BPoleman, op CII, Ref 4, Quantifying the nutntlon sltuatlon In developing countnes , Food Research lnsfrtute Studres, Vol XVIII, No 1, 1981, pp l-58 ’ ‘/b/d 2o At present the FAO food balance sheet represents the only source of worldwlde InformatIon on Food supply/consumption levels National surveys provldmg food consumption data are still limited In number and usually correspond to different time periods’ These are the opening sentences In FAO A Comparatwe Study of Food Consumpbon Data from Food Balance Sheets and Household Surveys. Statistics Dmsion, FAO, Economic and Social Development Paper 34, FAO, Rome, 1983

estimates

ot per

capita

aterage.

vex-round

potential

LarIatIon

re.glon to another nor

IS It

kno\\n

basis

lmposslble

In addition

In supplq In a country

those

Furthermore

IS

of Hhat

on dn

It IS eLIdent

accounted IS

bought

such

e\en

that

and trom

one

for In dnv uav.

‘~ctuallv

consumed

as Polemdn.

let alone

to measure

The

of

data

uSes

precIseI\

FBS

such

seasonalitv

tor

m eftect

these

dlstmctlons

esttmatlng

Intormatlon. IS

measurement

and tor

\\lth

dnv xcurx\

consumption

changes

365 days

ocer

and

would

time

cannot

I’)

require

Equdllv

take

the

account

ot

in int&e

Per caplra

ciarly

mttakrr

the

method

that

dlfterent.

IS not

adlust-

taking

the year (In time)

(In place)

what proportlon

against

consumption

to the errors

throughout

countrtes.

Given

cnutlons

to represent

potential

among others point5 out It IS to dlsttngutsh quantities entering dnd Ie,wng the retail sector produced dnd used entirely for home consumption In some

or who eats It and

contain

supplies ..

about

to to

It

IS In

calorie

Intake

many

countries

A cornparlsorl of

collectmg

some ways surprtsmg

aj two data

data

In

the

sources tHo

that the results

methods

IS so

In terms of dallv

per capita should be thought comparable Ho&ever not have Invested m nattonal HCS. certdlnlg not on an! regular basis. and reliance has therefore been placed on supply estimates - FBS - ns a basis for consumption Indicators “’ Is this reliance

FOOD

POLICY

August

1985

Justlhed” countries

those \%ho ulsh to calculate Intakes for Furthermore that do not ha\e regular HCS sur\e>s use FBS data as a

reterence

for data from other

sources

such as household

budget and

e\pendlture surveys. market sur\evs ,~nd Indlvldual dletarv surkeys ‘I Is this use of FBS valid” If per capita dally calories from HCS and FBS dre compared for any g~\en countr) the estimates from FBS seldom match HCS,

for developed

Table I sho\\s data and FBS for We

countries

the) are almost alHd>s more than HCS

kIlocalorIes (kc&) per capita. per day from HCS South-east Asian countries - Indonesld. Jap‘m

011

hlala>w Phlhppmes and Th‘lrland It cdn be seen that there IS a dlscrep;lnq between the t\\o sets ot data rnnglng from ,ibout 750 kcals (Thailand) to about 610 kcals (Japan) This obser\atlon IS not neh It has been known tor man! years and 21Reutllnger and Selowsky, op c/t, Ref 3 present an estimate of numbers malnounshed In the world where the Intake side of the equation IS measured by exploltmg the known relationship between Indome -and calorie consumption from household budget surveys A fuller cntique of their methodology can be found In Ref 4. but It should be noted here that they force’ their household budget data to ht that from FBS They say of HCS data that they cannot be used directly for assessing the global dimension of food consumption by Income groups without first reconciling the extrapolated data from such surveys and available data about national total food consumption’,by which they mean FBS “M C Burk and E M Pao, Analysrs of Food Consumpbon Survey Data for Developrng Countnes Food and Nutrition Paper 16, op c/t, Ref 20 Z3MAFF, op c/f. Ref 12 24Further data from these countries, which were chosen to demonstrate the dlfferences In national development in welfare status for the poor, form the basis of an m-depth study of nutntlon Indicators at different stages of national development See Y 0 Seo. Patterns of nutrition indcators at different stages of national development , unpublished PhD thesis, Faculty of Medicine. University of London, London UK, 1981

literature

Discrepancies

gathered

nuts

and

oler or

truer.

dlscussed

IS usualll!

defmlrlon alcohol

ot are

food

III p,lsslng

(u hether

Included)

and

In the

casually the

non-

of time periods are the usual rr‘rsons glien

” Ho\ie\er. figures ‘Ire usuall! published Inclusive and e\clusr\s ot alcohol. and aild foods bvould make little substantial difference to mean energy figures compdrablllty

Another

posslblht!,

eaten

rxpldnatlon

IS

that HCS tall to tahe sufficient

IS

the

outside

home

Inadequate

Such evidence

as there

account of me,lls IS.

suggests this

to account tor the slzeable dlscrepancles

”

The five countries whose HCS dnd FBS data dre quoted were selected tor stud!

because

their

polItIcal

and

frze-marhet

economic

systems

\\ere

ethnic groups (Chinese. hIala> and Thai) and 111 the troplcal zone between 15” latitude north and south ot the

slmrldr.

as mere

location eyu‘lltor

Data

their

on J,lpan

similar chdracterlstlcs

were

collected

so that

a debeloped

country

Hlth

was Included In the stud) ” It the data trom these

Include an Indicator ot economic development. such as GNP per head. and the countries are ranked accordlng to GNP It cnn be seen that both consumption and suppl) tlgures rank them In the same order

countries

as GNP rhan

(Figure 2)

the

IncreasIng tionship

GNP

e\tensl\e

not only

national

the FBS estimate

dlwaq’s

higher

tood supply estimates

from FBS and mtdhe

not constant betiieen dlfterent countries Moreover. changes Mlth GNP this suggests that the dlscrepdnq

as the economic - and the food - system becomes more and complex It IS also hheli that \%ith Increasing complevtv.

Table 1 Energy supply and consumpbon countries (kcals per capita, per day)

Food balance sheets’ Indonesia Japan Malaysia Phlltpplnes Thalland

IS

but the dlscrepanq Increases ulth obser\atlon suggests that. Hhate\er the relameasure

IS. It IS

rel,itlonshrp

Increases

This

between

from HCS the

However

consumption

2116’ 2833 2521 2290 2282

measurements

for selected

Household consumption survey

South-East

Aslan

Discrepancy

1832= 2188’ 2085e 1804’ 2037g

284 645 436 486 245

Sources a FAO op ot Ref 16 except Phlllpplnes Food and Nutntlon Research lnstltute

Manila the Phlllppmes Pub No 75 1976 ’ FBS for lndonesla 1970 1972 kcals per capita This reduces the discrepancy to 140 kcals ‘Bureau of Statlstlcs. lndonesla Survey Social Ekonoml Naslonal (SVSENAS) 1970 d Annual Report Naf/onal Nulr~bon Survey, Mmstry of Health Tokyo Japan 1975 ’ lnstltute Medical Research Mmlstry of Health Kuala Lumpur Malaysia 1975 ’ Food and Nutntlon Research lnstltute Pub No GP-11 1979 and Income and Food Consumpf~oon Report 1975 Mmlstly of Agnculture Quezon City. Mamla. the Phlllppmes, 1979 g CornplIed from Mlmstry of Public Health Household Expenditure Sutvey!Soaoeconomlc Survey 1975-76 Nattonal Statlsbcal OffIce National Social and Economic Development Board 1977-76

FOOD

POLICY

August

1985

283

(Food balance she&

Uiousehold consumptmn survewl

220 350410

Figure 2. Cross-country

I

Indonesm Phlhppmes Thatland

comparison

the

system

%tttsttcal

becomes

more

which

sophisticated

760

2550

Malaym

Slwre

4450 Japan

documents the economic system Itself It may well reflect more accurately

Thuc

the food supply per capita within a country, that IS. as national Income Increases. FBS data become more rellahle Several writers. Poleman In particular. habe commented on the probablllty that FBS consistently and perhaps grossly underestlmates the reahty of tood supply In developing countries ” Indeed It IS hkelv that HCS also under report consumption for very poor households The latest study from FAO documents a number of studies comparing household 25Poleman, op crt, Ref 18 26FA0, op cut, Fief 20 “/b/d, p 14 “/b/d. p 8 =/b/d, p 15 30A J Culyer, Measunng Health Lessons for Ontarro, Ontano Economic Council Research Studies 14, University of Toronto Press, Toronto, 1978, N Baster, Socral hdrcators and Socral Sfatrsks MI Conlexf of FAO’s Concerns, ESS/MISC/78-5, FAO. Rome, 1978, R A Bauer, ed, Social Indrcators, MIT Press, Cambridge, MA, USA, 1986, E A Dowler. P R Payne, Y 0 Seo, AM Thomson and E F Wheeler, Nutntlonal status Indicators - mterpretatlon and policy makmg role’, Food fohcy. Vol 7, No 2, 1982, pp 99-l 12 In particular, this paper draws a dlstlnctlon between shorthand Indicators (ie those that act as an indirect measure of the variables of Interest because they are quaker, easier. cheaper to measure for example, the price of rice can be used as a shorthand Indicator for all food prices) and proxy Indicators (ie those Indicators which stand as proxy for a set of variables or aspects of a particular system which cannot as yet be precisely defined For example, the Infant mortality rate might be used as a proxy indicator of health - health being a concept open to multiple definetlons and Interpretation )

284

data with FBS estimates (Table

3) ” The discrepancy

varies

this time between -579 kcals to +llOO The authors suggest particular food group\ which thev speculate might contribute to the differences observed (mostly nuts and oilseeds. fish, sugar products. and roots and tubers) though with no attempt to quantify their contnbutlon However their main conclusion IS that since FBS are estimates at a different level In the system from household suneys, the latter by defmmon not accounting for non-household food use (which they think might be

substantial In ‘developed’ countries). FBS data should be larger than the data derived from household surveb\ The mdgnltude of the discrepancy varies trom one country to another’ 2T We would not disagree with them thus fx where we hould part cornpan! IS In their contlnual assertion that Hastage ‘It the household level especial& In developed

countries.

final conclusion tood balance

that.

for part of the dlscrepancv ” and In their In the absence of datd from household sunejs.

account\

sheet data provide

a good proxy

for food consumption

levels ot the population’ “) Much has been wntten else&here on the theoretlcal nature dnd “‘The essential characterlstlc of an Indicator practlcdl uses of Indicators IS that It should bear a predictable consistent relatlonshlp Hlth the quantity It IS representlng or descrlblng In other words. one could tolerate FBS as shorthand Indicator5 of food consumption It one could characterize the relatIonshIp between FBS measures dnd actual consumptlon surveys The realit! IS that this cannot be done the relatlonshlp between the two sets of data IS not constant between

countries

nor necessarily over time

FOOD

POLICY

August

1985

Table 2 Household data and food balance sheet esilmries Per capita dally calones

Country survey DEVELOPED

Difference As percentage of per capita daily calorie derived from FBS

HS

FBS

Number of calones

2640 2696 2694 2122 2454 277 I 2313 2254

3293 3049 3150 3208 3328 3165 3169 3111

- 653 -353 -456 - 1086 -874 -394 -856 -857

-198 -11 6 -145 -33 9 -26 3 -124 -270 -27 5

1986 1917 2170 2817 2514 1951 2054 2192 2633

1880 2249 2026 2249 2497 2223 2039 2363 2501

+106 -332 +144 +568 +17 -272 +15 -171 +132

+56 -148 +7 1 +25 3 +o 7 -122 to 7 -72 +53

2110 2292

2439 2860

-329 -56%

-13 5 -199

COUNTRIES

The mcome,expendrfure‘budget survey Auslna (1974-75) FInland (1976) France (1977) FR Germany ( 1978) Greece (1974) Hungary (1971) Norway (1977-79) UK (1979) DEVELOPING

COUNTRIES

The ~ncome,expend~lure~~udgel survey Bangladesh (1973-74) lndonesla (1978) lndla (1971-72) Iraq (1972) Morocco (1970-7 1) Pakrslan (1971-72) Phllrpptnes (1975-76) Sri Lanka (1969-70) Tnnldad and Tobago (1970) The food consumptron survey Nofe HS = Household Survey Balance Sheet See text op at, Ret 20

FBS = Food

Brazil (1974-75) Turkey (1974)

Where does the energy go? The relatIonshIp between natlonal food supply estimates from FBS ,md Intakes from HCS IS not constant among countries. and It changes with GNP We suggest that the Increase m discrepancy between the two with rlslng GNP IS a consequence of the mcreasmg comple\lty of the food system - In storage. transport. processmg and marketmg - and Its as yet undocumented losses. particularly of energy Support for thrs Idea rn addltlon to the cross-sectional data above comes from a fairly unique set of longltudmal

data

from

Japan ‘I These

enable

comparisons

to be

made over time A natlonwlde survey of household food consumption (seven-day weighed Intakes) has been carried out annually for the last 30+

years

period

During

the 1950s and

of rapid economic

growth

196Os, the country and was transformed

experienced

a

mto a highly

centralized, mdustrlahzed society Figure 3 shows the average calorie Intake from HCS tor vanous years and the corresponding value for average calorie suppI) from FBS for the same years, plotted against GNP (US$) on a log scale The average calorie Intake from the HCS remdined reasonably constant over the period considered However per capita calorie supply from FBS rose rapidly as GNP Increased. especially after 1958 when GNP Increased rapidly Before then. It was about lo_?-104% of the per capita calorie intake from HCS By 196-I. It had risen to 115% and by 1973 to 129% Thus the reldtlonshlp between

31Seo, op at, Ref 24

FOOD POLICY August 1985

measurements of food consumption and food supply m a country which experiences rapldly lncreasmg Income IS quite complex, and changes with the level of income

285

(Food balancesheets1

A FAO countt-v reouWement (Hourehold ConslJmptlon SUI-WVSI

Figure 3

Longltudmal

comparison

(Japan)

I

I

I

I

I

220 1963

350 1958

760 1964

2450 1972

4466 1975

The FAO Statlstlcdl Offlce the discrepancy at mdlvldual that

further

study

of the

GNP US t log scale

Study urges detailed stud) ot the nature of country levels ” It certainly seems to us

Japanese

system

would

yield

some

required Insights Data from the UK has been mvestlgated wds expected that a country llhe the UK, where the tendency larger

productlon

cfflclent records.

units.

centralized

an earlier productlon

and

reasonably

annual figures of National supplies of produced In a similar wa) to FBS for from statistics ot total tood supplies at

stage of the dlstnbutl\e chain rnther than These consumption lekel estimates (CLE)

more accurate and less of an overestlmate the) are denved by d more sophlstlcated energy

keeping

sytems of taxation crop yeld estimates and stock movement would be able to rndlntam d high degree of accuracv In FBS

estlmdtes The MAFF publishes food moving into consumption’. FA0.‘3 but In this case derived

32FA0, op c/f, Ref 20 336rdrsh Busmess. (prewously In Board of Trade Journal), for example, Vol 37 No 11, pp 573-575, 14 December 1979 gwes consumption supply estimates for 197578, MAFF, op c/t, Fief 12 34NFS. personal communlcatlon 350p crt, Ref 33

record

of the

turther It IS towards

as kcals per capita

for

1975-80

trom on-farm dre said to be

than the FBS figure because method ” The figures tor

are shown

In Table

3 and var!

between 2920 and 3850 ” However. the national HCS for the same period gives 2390 to X30 kcals per capita. per day the discrepancy IS around

6X1 kcals

That

IS,

the best estimate

of mean energy

Intake

m the

Notes NatIonal averages In kcals per capita. per day a These eshmales rnclude lood used In manulacture of soil drinks and sweets, food consumed In catenng estabkshments or rnstrtuhons(hosprtals boardmg schools, pnsons HM Forces) and purchased by mdrvrduals but not taken home lo the household supply Excludes kgures on alcohokc dnnk purchase shown under (v) Dna means not avariable, ’ NFS figures do not Include purchase of alcoholrc drinks sugar or chocolate conlectronery. sofi dnnks or meals purchased outslde the home Assumptrons and adjustments rn analyses concernmg the latter are set out rn the NFS publrcatron (op err. Ref 12) “Smce 1975 purchases of soft dnnks for the household supply have been recorded analysed and the figures presented separately, e Obtamed from the CLE ‘Thus figure skll excludes con sumptlon of alcohokc dnnk Source MAFF op crt Ret 12

288

Table 3 Nutritronal value of household food m the UK 1976-81

I) Consumptron level eslrmatesa II) NFSC kcals (MJ) (I) - (11) III) Soft dnnkf kcals IV) Sugar and chocolate confechonelya v) alcoholrc dnnks VI) (II) + (Ill) + (IV) (to nearest 10 kcals) (I) - (VI)

1975

1976

1977

1978

1979

1980

1981

2920

2920

2930

2920

2950

2850

na”

2290 (9 6) 630 I7 133

2280 (9 6) 640 21 139

2260 (9 5) 670 18 138

2260 (9 5) 660 19 144

2250 (9 5) 700 19 141

2230 (9 4) 620 21 133

2210 (9 31

160 2440

166 2440

164 2420

176 2420

181 2410

174 2380

166 2360

480

480

510

500

540

470

FOOD

POLICY

21 130

August 1985

.-lssrattwnr01
data IS 3SV0 higher

the natlonal

the discrepancy

HCS

than measured

The MAFF

for a number

mean energy

has been Investlgatlng

of years and one potentId

Intakes

the basis of

explanation

was

thought to be the underesttmatlon of true Intakes dt the household lebel because of waste and losses The findings of the Food Waste Surve! Unit published so fdr suggest that domestic unlikely to exceed the 10% allowance already Some further work examlnmg the accuracy

Hnstage and losses are made jh of the supply estimates

and documenting losses In the system (that IS. between farm gate and food entering the household) has been published. much IS as jet unpublished For Instance. a recent UK dnal>sls b> Rov suggests sources of error m FBS from losses on farm (nearlv XI”,) and during processing

(about

9%)

losses to the food

” The rrlatlonshlp

system,

hedged

between

about

with

Roy’s

careful

estimates

deflnltlons

of and

ranges of figures as the! are, dnd the process tor cdlculatmg CLE 15 not cle‘lr, but may well contribute to an understanding of the dtscrepanck One problem Roy faced was the absence of reliable relevant mformatlon the UK food system 15 tdlrly centralized and documentable surveys m the 19hOs or from 36The publlshedlosses of 4-6% potential food energy being dlscarded IS presumed to be a mlnlmumestimate and the deductlon has therefore remained at the conventlonal 10% level, op cut, Ref 6 37R Roy, Wastage m the UK Food System, Earth Resources Research Publlcatlons. London, 1976 The percentages given refer to wastage as a proportion of edible material entering supplies or of potential agricultural yield (~7) The Report examines the problems in defining waste and losses’ between farmgate/dockside and the household and, stressing how widely ‘percentage wastage’ vanes from one commodity to another, emphasizes how mlsleadlng average figures can be when they are used out of context of the data and calculations on which they are based Nonetheless, Roy gtves a good summary of then existant evidence for the proportion of food destined for consumptlon which IS dlverted to other uses at each stage of the food system and that which flnally reaches the plate and IS consumed =D D Singer. Food losses In the UK, froceedlngs of the Nufntron Socrefy, Vol 38, 1979, pp 181-186 39R Osner, ‘Food wastage , Nutntlon and Food Scrence, No 77, 7982, pp 13-17. Rov. OD c/t Ref 37 All these authors (Refs 37:39) summarize work from several surveys Including their own Figures given are for energy In plate waste as a proportion of energy consumed 4olb/d 4’See also Anne Chinnock, Food consumption in Great Britain 1969-1978’. MSC Thesis, Depattment of Human Nutntlon. London School of Hygiene and Tropical Medicine. University of London, London, 1981 42K Mellanby, ‘Wasteline , Nature, Vol 257, 23 October 1975, pp 639

FOOD

POLICY

August

1985

In another. briefer largely undocumented

contemporary Fophlstlcated.

let many ot the data he quotes the LISA

are from

summary rebleu Singer Instance\ examples ot food waste m food proces>lng and dlstrlbutlon

both of that Intended for human consumption but not reaching the household (as In the retail sector - unsold fresh tood such as bread or milk

\thlch

foodstuffs

might which.

be returned through

to the supplier

processing.

or destroyed)

become

unavailable

and

for consumption (such as sugar effluent In s\ieets preserkattie ture. losses In fish processing to produce tush fingers) ” Work

has also been conducted

on catering

kitchen

of

or unusable manufac-

and plate

u‘lstage

In mstltutlons m the LJK 3y Such data suggest that the losses as a percentage of Indl\ldual mean intakes ot energb are higher than In domestic households and more Larlable Not surprlslngl\. \iastage In hospitals (hotels.

tends to be highest (up restaurants and conterence

to XI”,). hdlls)

IS

that In prltate catering ne\t highest (10-17%).

wastage levels m schools and work/student retectorles to that m domestic households (3-6”0) “’ The

UK

N,ltlonal

consumptron outside

the

Food

surveys. home

does

The

Sur\ey. not

In common

measure

published

food

reports

seem to be slmllar with

man\’

purchased

national and

eaten

discuss this Issue and the

allowance made In terms of meals dnd also the purchase and consumption of sugar confectlonerq, sott and alcoholic drinks Table 3 contains their esttmates derived from supply tlgures. dddlng those tor sugar and soft drinks to the consumption tlgures and comparmg these with CLE still leabes a dlscrepancv the HCS averages ” This used Intakes

issue

IS

to assess across

obvIousI) the

adequaq

developed

ot around

Important of

given

Intahes

500 heals

le Jbout

the srtuatlons and

\h here FBS are

In particular

and de\elopmg countries

It

22% ot

IS

comparatl\e

also Important

given the prominence of the word ‘nastage’ m man! current dlscusslons of the problem It IS all too easy to use the emotlbe word waste’ wthout consldermg Its tmphcatlons The Chief Scientist at hl;l\FF. to take but one example, has been quoted as clalmmg that of the toad bought In Bntam. as much as a quarter may be wasted’ A?The moral lmpltcatlons of the Idea that profligate consumers of the developed world are

carelessly emptymg valuable calories down their throats, their sinks or Into their dustbins (or worse still teedlng them to their pets) are attractive to Journalists. pohtlclans and even academics who wish to castigate the wasteful, but the facts do not bear out the allegations ‘Waste as a teature of atfluent societies does not seem to apply to the member cltlzens at least where household food IS concerned Indeed. Roy comments as a result of his stud! that the evlstence ot a certdln IsLeI of wastage

m the tood

since It represents of necessity’

system

a slacb which

ma!

e\en

can to some

be considered

extent

be taken

desirable up In times

-I’

Conclusions Despite

several

years’

effort

to Improve

the

technical

aspects

ot the

methodologies. the two sources m common use as Indices of nutrient consumption gibe dltferent aberage per capita figures tor dally energ) Intakes constant 43Roy, op crt, Ref 37, p 29 It IS possible he was bemg misquoted, as the NatIonal Food Survey m the UK records food bought at the household level, and has used a 10% wastage estimate for many years, perhaps he said ‘brought which would be nearer the mark Alternatively he may have been mcludmg food purchased by restaurants, canteens and institutions, which would make the estimate more reasonable 440p at, Ref 1 ‘?Iavld Southgate, In an editorial in the Bntlsh Nutntlon Foundation, Nulr~tron Bulletm, No 41, Vol 9, No 2, 1984, pp 57-58 Consumption level estimates and the NACNE discussIon paper’, comments adversely on the relationship between current UK recommendations for healthpromotmg’ diets and the measurements of intake on which this advice IS based

288

cy

IS

Furthermore. the between countries.

related

and that

size of this or over tune

to at least one other

the nature

have demonstrated of the notion that

of tha

difference IS not necessanlq This change In the dlscrepan-

socloeconomlc IS

relationship

Indicator

as yet unknown

that of GNP. Flnallv.

we

our rejection (at least where the UK IS concerned) wastage at the household level can account for the

discrepancy Food balance sheet data are theretore an unreliable calorie Intakes and. In addition. are subject to systematic

estimate ot error which

becomes

of the food

progressively

larger

~lth

increasing

sophlstlcatlon

system Household consumption surveys. despite their Inherent sources of error, are more hkely to give an accurate picture of calorie intakes Statements concerning comparisons among countries’ consumption levels.

about

SOFAq4

or

about about

the relatlonshlp between food/nutrient intakes and health,J’ the size and nature of International ‘toad gaps or estimates

or of

the numbers

the slgmflcance

malnourished

data and not on consumption.

of trends

m time for example

In the world should

that are based on food

be regarded

FOOD

supply

with great susplclon

POLICY

August 1985