Introduction to Human Nutrition

242 Introduction to Human Nutrition

they are being used. One of the crucial factors in using
the data appropriately is to understand the terminol-
ogy used. Box 10.1 provides “in principle” defi nitions
of the key terms.
Food balance sheets provide important data on
food supply and availability in a country and show
whether the food supply of the country as a whole is
adequate for the nutritional needs of its population.

Over a period of years, food balance sheets show

trends in national food supply and food consumption

patterns. They may be used for population compari-

sons such as comparing population estimates of fat

intake with cardiovascular disease rates.

In practice, the data needed to compile food balance

sheets are not always available and imputations or

estimates may have to be used at each stage in the

calculation of per caput food and nutrient availability.

In most industrialized countries reliable data are

usually available on primary commodities, but this

is not necessarily the case for the major processed

products. For example, data may be available on fl our

but not on products such as bread and other cereal

products made from fl our that may have quite differ-

ent nutrient characteristics. The overall impact of

incomplete data will vary from country to country,

but it has been suggested that in general underestima-

tion of per caput availability of nutrients is more

likely in less developed countries and overestimation

in countries where most of the food supply is con-

sumed in the form of processed products.

It is also very important to keep in mind that food

balance sheets show only data on foods available for

consumption, not the actual consumption of foods;

nor do they show the distribution of foods within the

population, for example among different regions

or among different socioeconomic, age, and gender

groups within the population. Food balance sheets

also do not provide information on seasonal varia-

tions in food supply.

Product-level food supply data

In some countries (e.g., Canada and the USA) data

on per caput food availability are prepared from

information on raw and processed foods available at

the retail or wholesale level. Such data are derived

mainly from food industry organizations and fi rms

engaged in food production and marketing such

supermarkets. Errors arise mainly from inappropriate

conversion factors for processing, the absence of data

for some processed products, and the lack of data on

food obtained from noncommercial sources such as

home gardens, fi shing, and hunting.

Commercial databases such as those produced by

the AC Neilsen Company and the electronic stock-

control records from individual supermarkets, from

which they are compiled, have the potential for moni-

toring national-, regional-, and local-level trends in

Box 10.1

Commodity coverage: all potentially edible commodities whether

used for human consumption or used for nonfood purposes.

Exports: all movements out of the country during the reference

period.

Feed: the quantity of the commodity available for feeding livestock

and poultry.

Food quantity: the amounts of the commodity and any commod-

ity derived therefrom available for human consumption during the

reference period, e.g., for maize includes maize, maize meal, and

any other products derived from maize that are available for

human consumption.

Imports: all movements of the commodity into the country, e.g.,

commercial trade, food aid, donated quantities, and estimates of

unrecorded trade.

Industrial uses: commodities used for manufacture for nonfood

purposes, e.g., oils for soap.

Per caput supply: adjustments are made when possible to the

resident population for temporary migrants, refugees, and tourists.

The fi gures represent only the average supply available for the

population as a whole and not what is actually consumed by indi-

viduals. Many commodities are not consumed in the primary form

in which they are reported in food balance sheets. To take this into

account the protein and fat content shown against primary com-

modities are derived by applying appropriate food composition

factors to the relevant amounts of processed foods, and not by

multiplying the quantities shown in the food balance sheet by food

composition factors relating to the primary commodity.

Production: total domestic production whether produced inside or

outside the agricultural sector, i.e., includes noncommercial pro-

duction and production from home gardens.

Seed: quantity of the commodity set aside for sowing or plant-

ing or any other form of reproduction for animal or human

consumption.

Stock variation: changes in stocks occurring during the reference

period at all levels between the production and retail levels, i.e.,

stocks held by the government, manufacturers, importers, export-

ers, wholesale and retail merchants, and distributors. In practice,

the available information often only relates to government stocks.

Waste: commodities lost through all stages between postharvest

production and the household, i.e., waste in processing, storage,

and transportation, but not domestic waste. Losses occurring

during the manufacture of processed products are taken into

account by means of extraction/conversion rates.