278 Introduction to Human Nutrition
important roles in the consumption patterns in under-
developed and developing countries increases this
need for food composition analysis. Food analyses are
also needed under the following circumstances:
● when the data in existing tables are based on a
single or very limited number of samples
● when the content of a nutrient or other food com-
ponent is not available in an existing food table
● when there is no information available on which
foods are important sources of a nutrient or another
food component of interest
● when there is no information on the loss or gain of
nutrients in foods during preparation by the
methods being used by the population under
investigation
● when it is necessary to check the comparability of
the various food composition tables being used in
a multicenter study
● when the method available to determine a particu-
lar nutrient is considerably improved
● when scientifi c evidence is found correlating newly
recognized food components to health
● when new foods are produced or existing foods are
reformulated.
11.2 Foods
Food composition tables normally consist of a list of
selected foods with data on the content of selected
nutrients in each food. For a food composition table to
be of value in estimating nutrient content, a signifi cant
portion of the foods consumed by the group or indi-
vidual being studied, as well as the nutrients of interest,
should be present in the table. To a large extent this
relationship is critical in determining the quality of the
information obtained by using the tables, assuming
that the data in the tables are of a desirable quality.
Criteria for inclusion in tables
The identifi cation of potential contributions of foods
to the diet of the population group being studied is
unquestionably the fi rst step in identifying and select-
ing which foods should and should not be included
in the production of a database. However, common
sense dictates that it is unreasonable to expect that
all foods consumed by all individuals at all times be
included in a specifi c food composition table at any
one time. Therefore, most tables aim to include all
foods that form a major part of the food supply and
that are major contributors to the diet in the forms
most commonly obtained or consumed, and as many
as possible of the less frequently consumed foods. For
instance, in the USA the number of foods contribut-
ing to quartiles of critical nutrient intakes was identi-
fi ed as the following: 9 foods contribute to 25% of
food intake, 34 foods to 50%, 104 to 75%, and 454 to
approximately 100%.
Databases can be compiled directly, where the
compiler initiates sampling and analyses to obtain the
data, or indirectly by drawing on the following sources
of data, in order of preference:
● original analytical values
● imputed values derived from analytical values from
a similar food, e.g., values for “boiled” used for
“steamed”
● calculated values derived from recipes, calculated
from the ingredients and corrected for preparation
factors
● borrowed values (refers to using data originally
generated or gathered by someone else) from other
tables and databases.
Today, database compilers normally draw on a com-
bination of the direct and indirect methods.Description of foods
The food described in the food composition table
should be recognizably similar to that being con-
sumed by the individual or group. The precise descrip-
tion of foods is a diffi cult task and much is required
to ensure that foods are described adequately. The
introductory material (description and explanation)
in a printed table may be almost as important as the
data values. By using several words to describe a food,
called an extended or multifaceted description, the
chance of misinterpreting the data is reduced. As
internationalization of food composition data con-
tinues, linguistic aspects of defi ning foods, with one
defi nition meaning different things in different cul-
tures and even from place to place within countries,
are highlighted. For instance, sorbet or sherbet is
made by beating whisked egg whites into the partly
frozen mixture such as in apple sorbet and lemon
sorbet. However, the term sorbet is preferred to
sherbet, since the latter can also refer to a fl avored,
sweet, sparkling powder or drink, or a drink of sweet
diluted fruit juice. The name tortilla is also applied to