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Data Base
Requirements
The proposed monitoring and evaluation system requires the use of sources
of data on food composition, nutrient requirements, aggregate food disap-
pearance, and health. There is considerable variation in the adequacy of
these data sources. The information may be incomplete, inaccurate, and out
of date. It is necessary, however, to deal with the data that are available as
the cost of collecting new data specifically for use in the proposed system
would be prohibitive. There must be a continuing effort to upgrade these
basic data sources in terms of quantity and quality of information and ease of
access for use. This chapter discusses the sources required and many of the
limitations that exist in the information they currently provide.
FOOD COMPOSITION DATA
The U.S. Department of Agriculture maintains the most extensive bank of
data on food composition. The quantity and quality of the data are variable
and in the case of many of the less studied nutrients are not adequate for an
accurate calculation of nutrient intake.
Data for the nutrients for which need has long been established are rela-
tively complete for food commodities. Data are much less complete for
commercially prepared items, although much more information is becoming
available as a result of nutrition labeling of many food products. For a
number of the nutrients for which dietary requirements have more recently
been identified, analytical data are fragmentary. For some nutrients, in-
cluding several of the trace elements, content in food varies extensively with
geographic region and growing conditions. Therefore, meaningful analyti-
29
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30 ASSESSING CHANGING FOOD CONSUMPTION PATTERNS
cat descriptions may be difficult. However, when interest is in usual intake
and hence usual composition, sample-to-sample variation in composition or
small differences attributable to various processing or preparation practices
may not be of concern.
For some studies, data on the composition of particular brands; changes
caused by processing, packaging, and storage; and variations in composition
due to changes in selection of ingredients (such as type of fat) may be
required. In other studies, information on the composition of the water
added to or used in preparation of the food items may be desirable. This type
of information is very limited.
Conventional tables of food composition do not provide information
about amounts of nonnutritive food additives or food contaminants present.
If concern exists as to potential toxicity of any nonnutritive components or if
dietary data are to be applied for prediction of risk of excessive intake, an
increased data base describing the levels or potential levels in food is
needed. Information on additive content in foods is currently available from
GRAS (additives Generally Regarded As Safe) survey data prepared by the
Committee on GRAS List Survey, Phase III, Food and Nutrition Board, the
Food and Drug Administration, and other sources.
As the needs of each study are different, decisions on the desirable detail
of description of foods must be made at the time of data collection. It is,
however, necessary to keep in mind potential future uses for the data.
The incomplete nature of available data banks currently limits the attain-
ment of accurate and useful nutrient intake data. Current data bases must be
expanded to include some information on formulated, processed, and ethnic
foods as well as mass-produced fast food items and products prepared for
institutional use. More data on a wider number of nutrients for many foods
should be provided.
The ideal data base would (1) be current, reliable, and valid; (2) be
responsive to changes in the food supply; (3) contain information on all the
nutrients of interest; (4) have complete data (unavailable data should be
extrapolated until analytical values are obtained); (5) be expandable as new
data become available; (6) reflect differences associated with brands; and (7)
be in a physical form that facilitates coding and analysis.
Coding System
Concurrent with the further development of data banks for nutrient analysis
must be the development of a coding system that will allow maximum
flexibility in analyzing data and identifying and tracking trends in food
consumption patterns. Coding by the various food consumption data banks
must be standardized so information from several sources can be efficiently
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Data Base Requirements
and easily combined. The coding system must be designed to mesh with
health data systems. Simplified analyses based on dietary scores or the use
of indicator nutrients warrant further investigation to enhance the usefulness
of the data for various purposes.
31
Nutrient Requirement Estimates
It is customary in evaluating data on dietary intake to compare calculated
nutrient intakes to the Food and Nutrition Board's Recommended Dietary
Allowances (RDA). This practice leads to misinterpretation of nutrient intake
data. Intake data may be interpreted more accurately by a bivariate distribu-
tion approach that requires a description of the distribution of nutrient re-
quirements (median plus variance). For many nutrients, these data are avail-
able. For other nutrients, appropriate informed judgment can be made about
the distribution of requirements and, thus, the extent of variance. For a few
nutrients, there are insufficient data to permit even an informed judgment,
and interpretation of observed intake is not possible.
It will be necessary to compile existing data and prepare descriptions of
the distributions of nutrient requirements. Therefore, data on average re-
quirements and their variances should be collected and published. At the
same time it will be necessary to aggregate data on nutrient requirements for
different levels of nutritional status if an assessment of both prevalence and
severity of nutritional risk is to be made. Such data are available for many
nutrients. For example, the average requirement of thiamin to prevent
neurological manifestations of deficiency is estimated to be about 0.2~0.22
mg/1,000 kcal (FAD/WHO, 1967~. The average requirement for physiologic
saturation of tissue needs, judged by the pattern of urinary excretion, is
about 0.33 mg/1, 000 kcal with a coefficient of variation of requirement of
10 percent of the mean (FAD/WHO, 19671. Data are now available relating
thiamin intake to erythrocyte transketolase activity. These types of informa-
tion provide estimates of requirements for different levels of nutritional
status and can be used in the bivariate distribution analysis. Thus, in at-
tempting to relate dietary status to health status, it is necessary to express
requirement in terms of purpose: e.g., prevention of clinical deficiency,
maintenance of a level of enzyme activity, etc. To what extent all of these
criteria relate to health status remains to be determined.
AGGREGATE DATA
A number of ''food use" government and commercial data systems cur-
rently collect data on a continuing or periodic basis. These data series can be
classified by the degree of aggregation of the data that they present and,
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32 ASSESSING CHANGING FOOD CONSUMPTION PATTERNS
therefore, by the applications to which they can be put. Avenues for their
effective use in conjunction with individual data should be identified.
Production and shipment data are usually collected from the producers or
the distributors of the raw commodities of the processed foods. The primary
source of agricultural output data is the U.S. Department of Agriculture.
Other sources include the Department of Commerce, the Bureau of Census,
various growers or manufacturer associations, the state agricultural depart-
ments, and the alcoholic beverage production and tax control commissions
of the states and the federal government. Most of these data are published in
standardized time series.
Warehouse withdrawal data are collected from the data processing records
of large warehouses of supermarket chains, or food and grocery product
brokers. The data are aggregated and reported for a large number of markets
or cities. Information is presented on individual brands, by type of product,
by size of package, and for canned, packaged, refrigerated, and frozen
foods. Most fresh fruits and vegetables, fresh meat, and similar items that
do not move through the chain warehouses or the computerized inventory
management systems of the stores are not included. The data are usually
reported in raw unprojected form, covering sales in each market for the
cooperating chains. The system in many areas accounts for 50 to 75 percent
of all foods sold. The information is usually sold to food manufacturers and
advertisers on a product-class basis for confidential use and not for resale or
publication. Standard reports are usually issued, but customized processing
is possible.
Audits of in-store movement of food items are made by a number of
commercial services. These services collect their information from a
selected sample of supermarkets throughout the United States. A physical
audit of the quantities of various products on the shelf and delivered into
each store is made bimonthly. This information is then projected from the
sample to total market levels and aggregated into regional subtotals and a
U.S. total. Per-capita availability can be determined from these audits and
warehouse withdrawal data.
Aggregated consumer food purchase and usage data are collected by
consumer purchase panels. These syndicated data services collect informa-
tion via the mail from continuing nationwide samples of households and
project these data to regional and U.S. totals. Diaries are collected from
consumers weekly or monthly. Occasionally, custom samples are set up in
selected cities for test marketing purposes, operated for a period of from t/2
to 2 years, and then disbanded. Consumer records include mail-order,
door-to-door, and specialty store purchases in addition to grocery store
purchases. Reports are issued to subscribers on a monthly or quarterly basis.
Reports include data on the total quantity of the product bought, the average
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Data Base Requirements
33
price paid, the percent of households by which the product was bought, and
the average quantity bought per buying household. Data on consumption by
individuals within the household are not provided.
A "Menu Census Service" provides detailed information on food prep-
aration and on all food consumed at and away from home from regional or
nationwide samples. Data are collected by mail following maintenance of
consecutive days of diaries of individual food intake. Data for each food
product are summarized and reported quarterly and annually. Usage of each
food product is cross-tabulated by the demographic characteristics of the
household and the individual eaters. Persons living away from home or in
institutions (i.e., schools, hospitals, armed forces) are not included in con-
sumer purchase panels or menu census services.
Food consumption surveys of selected products or sources are conducted
by various companies. The data are collected by mail from consumers on a
continuing syndicated basis. Information on, for example, the consumption
of all foods at restaurants, or the consumption of all beverages at home or
away from home, is summarized into standard reports designed to satisfy
selected information needs of a given industry, such as soft drink manufac-
turers or restaurant operators.
HEALTH STATUS DATA BASES
Indicators of health status are objective measures of the state of health of a
population. Health status indicators with a nutritional status component fall
into several categories comprising the continuum from "perfect'' health to
death from a variety of illnesses and disease. The first category, morbidity,
includes specific diseases with an apparent nutritional component and ones
where evaluation of nutritional status would provide an indication of poten-
tial risk of the disease. Among these diseases, but not limited to them, are
noninsulin-dependent diabetes, atherosclerosis, hypertension, cirrhosis of
the liver, gout, osteoporosis, obesity, coronary heart disease, dental dis-
ease, anemia, cerbrovascular disease, and, possibly, cancer. Of less impor-
tance, but still significant, would be others, including gastrointestinal disor-
ders, respiratory disease, a variety of conditions subsumed within aging,
nutrient inadequacy and toxicity, chance contaminations, and food-borne
illnesses.
The next group of health status indicators may be drawn from mortality
statistics. Of particular nutritional importance are infant mortality, perinatal
mortality, and age-specific mortality rates indicative of longevity.
The third group are those indicators that are characteristics of the popula-
tion and are nutrition related. They include the incidence of low birth
weight, the age at menarche, the outcome of early adolescent pregnancies,
\
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34 ASSESSING CHANGING FOOD CONSUMPTION PATTERNS
birth defects, obesity, stunted growth, and behavioral or functional condi-
tions (including those related to learning and to performance).
Nutritional status indicators are considered a category of health status
indicators. They include the various types of measures by which nutritional
status is determined: (1) biochemical (including blood and urine samples),
(2) anthropometric, and (3) clinical (including behavioral measures). The
data derived from such measurements are used in two ways: to identify
individuals at risk who may then be recalled for follow-up examinations,
and to identify groups that are at risk and design appropriate programs to
alleviate the risk. Nutritional status determinations are complex, time-
consuming, and expensive.
The methodology of relating food consumption to information on health,
including nutrition status indicators, encompasses a range of data-gathering,
coding, and analytical procedures. The general types of food consumption
information desired for useful analyses can be divided into three groups:
1. Feeding behavior, which includes the pattern of meals within a family,
the type of infant feeding, the frequency of eating, the proportion and
location of meals eaten outside the home, snacking patterns, food prepara-
tion, and many others;
2. Food groupings, which can be as finely divided as the investigator
thinks necessary;
3. Food components: saturated and unsaturated fats, cholesterol, sugars,
other carbohydrates, fiber, animal and vegetable proteins, specific nutri-
ents, additives and contaminants.
Some aspects of a system for relating food consumption to health status
do exist, but the linkages can seldom be made due to inconsistencies in
methods and in populations studied. Existing information is often not fully
used, and studies are not often compatible with existing information sources
or with other new studies.
Monitoring for the conditions in populations can be at several levels and
may utilize already existing health or individual data or may require field
survey methods. Table 3 indicates sources of information currently available
on defined populations of suitable size to detect small area or regional
differences. The sources of information are varied, at present are not inte-
grated, may be redundant, and have varying degrees of validity. Develop-
ment of these information sources into a complementary, if not single,
information system should be undertaken.
Medical record linkage as a method to utilize the diverse sources of
information should be developed. Such development will require that cur-
rent concern about privacy and confidentiality of personal records be satis-
factorily resolved in favor of the ability to carry out epidemiologic studies.
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Data Base Requirements
TABLE 3 Types and Sources of Health Status Data
Vital Statistics
Birth records
National Center for
Health Statistics
Death records
National Center for
Health Statistics
Linked birth and death records
Public health agencies
Special studies
Medical Records
Hospital discharge data
Commission on Professional
and Hospital Activities
Professional Standards
Review Organization
Insurance data banks
Tumor registry
National data set
Local registries
Physician records
Group practices
National Disease and
Therapeutic Index
Insurance Claims
Institutions
35
Health Screening Program
Voluntary agencies
Public health agencies
Disease Registries
Voluntary agencies
Public health agencies
School Health Records
Population Surveys
National Health Survey
Special studies
Epidemic Intelligence
Centers for Disease Control
Public health agencies
Appropriate safeguards against invasion of privacy and breach of confiden-
tiality must be built into the system in such a way that linkage is not
proscribed.
At present there is a vast amount of information on mortality and morbid-
ity in existing computer tapes. Most of the types of data shown in Table 3
are currently collected and stored in accessible form. There is a need for new
ideas and methods to utilize these data sources in combination with food
consumption data in defined populations. For example, fetal nutritional
experience seems to offer an excellent prospect for studying chronic disease
within a realistic time cycle. Surveillance of various indices of infant birth
and mortality, linked to birth certificate data, and study of these data in a
comprehensive way could shorten the long observation periods needed to
collect mortality and morbidity perspectively in adult populations (Haw-
thorne, 198 1~.
For purposes of illustration, certain selected conditions considered at
present to be strongly associated with food consumption are listed in Table
4. The types and sources of health data that could be utilized in population
OCR for page 36
36
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OCR for page 37
Date Base Requirements
studies are indicated in the table. While the sources vary in the degree of
validity of the data contained in them, they form a rich pool of information
for assessment of the health of populations.
The many health data files that exist in the United States should be
cataloged and those that may provide data for relating health status to food
consumption patterns identified. It is recommended that a special work
group be established to evaluate current health statistical information and
recommend a system whereby these data can be collated in a manner that
will permit identifying population segments showing unusual health pat-
terns. Once identified, the integration of this information with the proposed
system for monitoring food consumption patterns should be developed. In
this manner studies can be targeted to specifically identified groups either
through special studies or as a part of the ongoing monitoring program.
If information on food consumption and nutritional status were obtained
in a compatible format, this system could be used to explore associations
between food consumption and health status, while taking into account the
modifying effect of other factors.
There is a current need in the United States for specific information on
food consumption and health status (obtained at the same time and from the
same individuals) in order to identify specific associations. There is an
additional need to obtain this type of information in a consistent manner, on
the same individual as often as possible, and at repeated time intervals in
order to detect trends and changes over time.
37
Representative terms from entire chapter:
health status
