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7
RATIONALE AND RECOMMENDATIONS
FOR LONGER-TERM rMPLEMENTATION
Some Committee recommendations of importance to data users are appropriate
for implementation over a longer term than those in Chapter 6. These recom-
mendations are discussed in this chapter.
The Committee acknowledges that implementation of these recommendations
will require time, money, and research. However, it urges that each of the
recommendations found in this chapter be given full consideration. Like the
recommendations in Chapter 6, the recommendations in this chapter have been
developed as a result of the Committee's information-gathering processes and
reflect an ef fort to respond to the needs identif fed by survey data users.
The recommendations in this chapter are related primarily to modifications
in food intake methods to include more detailed information in the survey data
bases, modifications in food intake information to expand and improve data
bases on the composition of foots, and the handing of the data themselves.
SURVEY PURPOSES AS GUIDES
This report has previously referred to the importance of considering
modifications of the surveys in the context of their separate purposes. The
purposes of the surveys serve as useful guides for identifying the agencies
most likely to be involved in undertaking the Committee's recommended activ-
ities or those most likely to serve as lead agencies if the Committee's recom-
mentations involve more than one agency or organization. Indeed, the Com-
mittee has uset the separate survey purposes as guides in developing some of
its reco~entat ions .
The Committee has developed recommendations both in relation to the
separate core survey purposes and from its perspective of the conjoint use of
the survey data bases in a system of nationwide food and nutrition monitoring
(see Chapter 5~. The recommendations in this chapter provide an opportunity
to consider the broadening of future uses of the separate core survey data
base..
FOOD INTAKE METHODS
Data users have identified several needs relates directly to food intake
methods. The Committee appreciates the importance of USDA's continuing pro-
gram of intramural and extramural research on food intake methods and comments
that effort.
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Given the primary purposes of the NFCS ant its
importance in the broad array of questions that must
be addressed through nationwide foot and nutrition
monitoring, the Committee recommends a continuing
commitment to that research program. The Committee
also recommends that DHHS adopt a similar program of
intramural and extramural research on methods, some of
which could be jointly undertaken with USDA.
Several of the recommendations fount in this chapter depend on the results
of research projects in progress. Others may require additional limited
research. Still others are likely to involve agency commitments of research
or personnel resources. The Committee regards these research commitments an
necessary, feasible, and cost-effective.
CONTINUED STUDY OF SURVEY METHODS
In citing the importance of replicated observations of 1-day intakes
(Chapter 6), the Committee envisions the use of these data to derive estimates
of the dis tribution of "usual" intakes among individuals . In turn, such dis-
tributions would be used to consider the prevalence of high-risk intakes,
whether such a risk is represented by low or high intake.
The Committee recognizes that for this purpose, where data are analyzed by
appropriate statistical techniques, in the longer term it may not be necessary
to continue to obtain 3 data-days of intake of all survey subjects. However,
such a longer-term design question must be addressed from the background of
the analysis of existing shorter-term data sets and, possibly, special data
collections.
The Committee strongly recommends that USDA
continue its investigations of survey methods. It
suggests that USDA, with the appropriate statistical
resources, then examine the design requirements of
tietary-data collection for proposed approaches to
tata analysis ant interpretation.
Other complementary approaches address the question of systematic under-
estimation of dietary intake. In earlier recommendations, the Committee
addressed some aspects of this concern regarding improving information on the
intake of dietary supplements (underestimation of essential nutrient intake)
ant discretionary food components (underestimation of energy and nutrient
intake). In addition, physiologic studies to validate intake methods, espe-
cially total energy intake, may be needed.
The Committee recommends that the agencies form a
joint working group to evaluate newer methods for
validating energy intake and expenditure es timates .
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The goal of the evaluation should be to identify
systematic error in estimating dietary intake of
energy and determine the bese method for correction.
USE OF UNIVERSAL PR~IICT CODES
Inadequate and inconsistent descriptions of food products create problems
in food coding and the estimation of the nutrient content of foods. One pos-
sible way of reducing this problem would be to make use of the universal
product codes (UPCs) that now appear on nearly all canned and packaged food
products and even on some fresh items that are repackaged in ~ tores 7. The
use of these codes permits automation in recording packaged foods (for
instance in home interviewa).
It remains to be determined whether the system of UPCs can become an
effective part of the data collection process. However, the nature of the
codes (their universality), the potential ease of obtaining information from
their use, and the precision (specificity) of their description of foods
suggest both their utility and the potential ease of incorporating them into
the survey coding process.
The Committee suggests that, to respond to user
needs for greater specificity in food descriptors,
consideration be given to the use of UPCs in
developing standardized food codes for the food
consumption and dietary intake surveys. The Committee
also recommends that, if automated data collection
applications of UPCe are shown to be feasible, such
automation be incorporated into the survey data
collection methods.
INFORMAT ION ON MEDICAT IONS
Many prescription and over-the-counter (OTC) medications can affect food
consumption, dietary intake, or nutritional 8 tatus . Patients taking some
medications may be advises to avoid particular foods or classes of foods when
there is come likelihood of a food~drug interaction. Some medicines interfere
with the absorption and use of nutrients. Other medications may substantially
increase a sub ject's total dietary exposure to a particular nutrient or other
foot component. Still other medications can affect the qualitative and quan-
titative data on biochemical indexes of nutritional status. Thus, qualitative
and quantitative information on meticatione unset by survey subjects can be
important in interpreting the qualitative and quantitative nature of the data
reported in the survey data bases.
The data bases on dietary intake in each of the
separate core surveys should contain more detailed
qualitative and quantitative information on
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- so
medications being consumed by survey subjects,
especially medications affecting nutritional status.
Interagency efforts, perhaps through a joint working
group, should be used to define the nature and extent
of the information to be contained in each o f the
survey data bases ant to design questions for the
separate surveys. On the basis of the survey
purposes, the Committee suggests that 1)HHS serve as
the feat agency in this effort. The Committee further
recommends that this process be sustained to foster
the continuing incorporation of information as new
needs emerge.
BRAND-NAME INFORMAT ION
Some data users expressed a need for more product brand-name identi fi-
cation of food items reportedly consumed by survey subjects. Users noted that
incorporation of such information into the survey data base tapes would foster
wider and easier use of the survey data.
However, consumer use of specific brand-name items can vary, e.g., with
price and availability. In addition, product label information, if uset for
nutrient-dependent questions, may not accurately reflect the amounts of the
nutrients consumed. Moreover, information on brand-name products may be even
less reliable when gathered outside the home setting, because such information
cannot be verified.
The latter circumstance is lees likely to have a major design implication
for the NFCS, because the NFCS is conducted entirely in respondents ' homes.
However, for the NHANES, with it. dietary interviews conducted in mobile exams
ination vans, the validity and ret lab ility of brand-name information that is
collected may be questionable. There may be major design implications for the
NHANES, if its dietary interviews were moves deco the household setting solely
to facilitate the verifiable collection of brand-name information related to
foot consumption ant dietary intake.
A further consideration in the incorporation of product brand-name infor-
mation into the survey data bases is related to the degree of specificity that
would be imposed on data collection in large national surveys. Under what
circumstances does the imposition of such specificity on large national
surveys become inappropriate, and when are smaller, specialized surveys more
appropr late ?
The Committee recommends deferring specific
modifications designed to increase collection of
product brand-name information in national surveys on
food consumption and dietary intake until information
on the utility of UPCs or other automa~ced systems for
collecting such data can be analyzed. The Committee
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-
recognizes the needs of some usere for this kint of
information. However, it is concerned that immediate
modification of food intake methods to collect such
data before itch validity, reliability, and utility in
reporting food consumption and dietary intake are
demonstrated may be premature.
INFORMATION ON IMPEI)IMENTS 'to FOOD - INTAKE
Various characteristics of survey subjects (e.g., food intolerances ) and
their environments (e.g., means of transportation) can seriously affect their
food choices and dietary patterns; those choices and patterns affect food
consumption and dietary intake. Individual characteristics and environmental
factors (including income) can be major determinants of food choices.
rently, impetimente to and determinants of food choices are not easily com-
parable or identifiable across the survey data bares.
Such food-selection factors can also be important in the selection,
design, implementation, and monitoring of food and
from highly selective public education programs to
vention programs. Impediments to and determinants
Cur-
nutrition programs ranging
broader national inter-
of food selection are thus
impor tent to both the independent ant the con joint us es of the core survey
data banes.
The Committee Bugged to that the separate survey
data bases contain some minimum of identical
information on determinants of food intake. The
Committee further sugges to that the nature and extent
of the core questions be determined and developed by a
joint interagency working group in a manner similar to
that sugges ted for the addition of information on the
use of medications by Survey subjects.
Many of these determinants may be more closely
relates to health Status than to foot intake. For
this reason and with the survey purposes as guides,
the Committee sugges ts that DHHS serve as the lead
agency in this effort.
IMPROVEMENTS IN INFORMATION ON COMPOSITION OF FOODS
,
Some Committee recommendations in Chapter 6 included ~ tandardization and
prompt expansion of the data bases on the composition of foods. Effective
longer-term improvements in information on the compost ition of foods are also
needed. Implementation of some of these longer-term improvements depends on
research in analytic methods, and implementation of others depends on the come
mitment of research resources.
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Recommendations in this section are related to research on analytic
methods ant to expansion of the Fate on nonnutritive foot components, foot
ingredients, and inadvertent components of foods. These recommendations were
designed to respond ~ in a continuing, feasible, and cost-effective manner --
to users' needs for more complete and more detailed data on what is being
consumed.
RESEARCH ON ANALYTIC METHODS FOR NUTRIENT DESTINATION
Several assessments of analytic methods used for the quantitative deter-
mination of nutrients present in foods have been reported. A recent
assesement38 is summarized in Tab le 7-l and illus theater that analytic
methods for a number of nutrients are not considered "adequate" for deter-
mining the content in foods . This Rugged to that currently availab le quanti-
tative information on these nutrients may be of questionable reliability.
In the view of the Committee, a priority goal of
federally supported research should be improvement in
the analytic methods needed to develop public data on
the composition of Foote. With the survey purposes as
guides, the Committee recommends that USDA serve as
the lead agency in efforts to expand and improve
qualitative and quantitative data on the composition
0 f foods .
The Committee sugges ts that a review of the s Lance
of analytic methods will be required to develop a more
complete data base on the composition of foods. The
Committee recommends that research resources be
provided, where necessary, to develop the appropr late
ant validated analytic methods needed. The
development of methods is particularly important for
foot components about whose dietary intake in the
United States, whether high or low, there is
scienti fic concern .
The Committee believes that a broat-based effort
for the development 0 f these methods is needed and
sugges ts that further programs for their development
use the resources of academia, government, and
industry. USDA and DENS, perhaps by establishing an
interagency working group, should address the need for
written criteria (e.g., both minimal standards and
adequate standarda) for the analytic methods used in
qualitative and quantitative assessments of the
composition of foods, evaluation of current methods
for food analyses, and strategies for establishing
acceptable assay techniques for the chemical analys is
0 f foods .
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In the view of the Committee, it is important
ensure consistency, comparability, precision, and
reliability in analytic meehode and in the
dissemination of information about both methods and
the determinations that result. The Corm ittee
suggests inclusion of representatives of both the
National Bureau of Standards and such appropriate
scientific organizations as the American Chemical
Society, the American Society of Testing Methods, ant
the Association of Official Analytical Chemists in
efforts undertaken to improve the analytic methods
needed to expand ~ tandartized pub kc data on the
compos it ion o f foods .
DATA ON NONNUTRITIVE FOOD COMPONENTS
Data from food consumption surveys have many current and emerging epidemi-
ologic applications. Some uses are baset on hypotheses that the intake of
food components, either singly or in combination, can be or is (directly or
indirectly) related to the cause or aggravation of human diseases. These
disease-related hypotheses are often linked to the ingestion of nonnutritive
foot components. An obvious example is the concern about dietary exposure to
and ingestion of nonnutritive presumptive human carcinogens in the food supply.
Naturally occurring nonnutritive substances of plant and animal origin
have been shown to have detrimental effects -- examples are enzyme inhibitors,
goitrogens, }athyrogene, and hemagglutinins. Considerable qualitative infor-
mation on these compounds in available.
However, very little available quantitative information is suitable for
incorporation into a Late base on the composition of foods. This lack of
information results, at least in part, from the absence of a systematic effort
to gather information suitable for incorporation into such data bases. Con-
siderable research on and development of appropriate analytic methods will
probably be necessary to obtain the data.
The development of tats on nonnutritive
components in food would benefit the users of national
survey data on food consumption and dietary intake.
Earlier in this report, the Committee has recommended
the development of appropriate analytic methods and
expansion of a standardized data base on the
composition of foota. Similar recommendations are
applicable to the longer-term development of
standardized data on nonnutritive food components.
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FOOD INGRED TENTS
Little quantitative information on foot ingredients is availab le in a form
suitable for incorporation into Fate bases on the composition of foods. In
most cases, such technical data will be relatively difficult to acquire,
because the number ? kinds, and amounts of these compounds may depend as
heavily on the food production process as on the food product formulation.
The Committee does not expect the immediate addition of quantitative infor-
mation about food ingredients into data bases on the composition of foods.
However, the Committee recommends that such
additions to data bases on the composition of foods be
considered as a longer-term goal. Committee
recommendations for the development of appropriate
analytic methods ant expansion of a standardized data
base on the composition of foods are also applicable
to the development of standardized data on food
ingredients.
INADVERTENT COMPONENTS OF FOODS
Concern about the chemical contaminants that directly or indirectly enter
the food sys tem is increas ing . For example, chemical s pit Is can contaminate
individual food products . Compounds can enter the food sys tem through contam-
ination of water or by soil, microbial organisms, or molds. Examples of
subjects of concern are heavy metals and aflatoxins in foods. Few data are
available on the amounts of these compounds 1 ikely to be found in foods .
Much current knowledge on these compounds is obtained from data on the
regulatory recall of contaminated foods. But quantitative data originating
from recall actions may not be useful for standardized data bases on the come
position of foods. Recall-related data involve foods that were not eaten, but
rather were recalled from the food supply because of the presence of sub-
stances in amounts higher than permitted. Moreover, current analytic methods
used to measure such substances may be designed solely to determine whether
the amounts of these substances were greater than some particular specified
amounts. Those methods to not yield good data on the usual or expected
amounts of substances that occur in amounts Smaller than the amounts resulting
in product recalls. Future data users would benefit if analytic data on the
usual or expected amounts of chance contaminants were available in a
standardized data base on the compos ition of foods .
The Committee does not believe that it is feasible to
expect the immediate addition of quantitative information
on inadvertent food components to data bases on the
compos ition of foods . However, the Committee recommends,
over the longer term, a systematic approach to the
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development of this information. Committee
recommendations for the development. of appropriate
analytic methods ant an expanded data base on the
composition of foods are applicable to the development
of standardized data on inadvertent components of
foods .
GENERAL USER NEEDS
The data users' conferences were designed specifically to develop infor-
mation on and recommendations for modifications in survey methods. However,
the Committee has chosen to include recommendations on come general user needs
that were identified during its own information gathering process. The recom-
mendations included here are related to storage and maintenance of data tapes.
Implementation of these additional but more general recommendations, although
not specifically a part of the Committee's charge, would also serve the needs
of future data users. The Committee therefore urges their consideration.
DATA TAPE STORAGE
.
The use of these data for analyses of changes in food consumption, dietary
intake, and health status with time and their use for other trend analyses
imply a continuing need for the data tapes over time. Some users have sug-
gested the need to ensure the storage and maintenance of data base tapes to
prevent their physical deterioration. This suggestion may also be applicable
to other data taper and is not of interest solely when data are collected on
food consumption, dietary intake, and health status.
The Committee suggests review of the technology
of data tape storage. It further suggests that the
agencies undertake continuing efforts to ensure that
the information collected and stored on these tapes be
protected from physical deterioration.
The Committee suggests that USDA, DHHS, and other
interested agencies, along with representatives of the
National Archives and Records Service, consider the
technical means that may be needed to ensure that data
tape information from federally funded surveys be
stored and maintained in a manner most likely to
prevent their physical deterioration.
SUGARY
In addition to recommendations for near-term implementation, the Committee
has addressed data users' needs that are likely to be implemented over a
longer-term. The Committee accepts the premise that these additional recom-
mendation~ will require both time and research resources. However, it urges
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their full consideration. The Committee has u~ed the purposes of the separate
surveys as guides for identifying the agencies most likely to be involved or
to be feat agencies in implementation of there recommendations.
Data users have identified several needs for data that are related to food
intake methods, including the need for continuing support of methodologic
investigation, the need for detailed identification and description of foods
consumed by survey subjects, the need for more detailed identification of
medications taken by survey subjects, and broader information on impediments
to food intake. The Committee recommendations related to these user needs are
based, in general, on their utility for users and with recognition of the need
for research or personnel resources before their implementation.
Some users also identified needs for more detailed and highly specific
information on the composition of foods. Although the Committee regards the
collection of these data as worth while, it expects broad expansion of the
public data base on the composition of foods to require a continuing, long-
term commitment to the resource needs of such an ef fort .
Some general user needs are also included in the Comer ittee 's recommen-
dations. Although not specifically within the Connnittee's charge, the general
recommendations are des igned to respond to needs of both current and future
data users for more detailed and long-term use of survey data.
.
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Tab le 7-l . State of Me thods
for Nutrient Analys is in Foodoa
Probab it ity o f Correct Analy~cic Value
Category High Good Fair Poor
Carbohydrates, Fiber, Individual Fiber
and Sugars - Sugars
S tar ch
Lipids Choles terol Sterols
Total Fat Homeric
Fatty Acids
Common Fatty
Acids
Minerale/lnorganic Calcium Total Iron Arsenic Cobalt
Nutrients Copper Selenium Chromium Molybdenum
Magnes ium Fluor ine S i 1 i con
Phosphorus lotine Tin
Potass ium Manganes e Vanadium
Sodium Heme Iron
Zinc Nonheme Iron
Proteins and Total Most Amino Some Amino
Amino Acids Nitrogen Acids Acids
Total
Protein
Vitamins
Niac in
Ribof lavin
~hiamin
Vitamin B6
Vi tamin A
Carotenes
vitamin B12
Vitamin C
Vitamin D
Hi tamin E
Folacin
Pantothenic
Acid
Biotin
Cho 1 ine
Vi tamin R
aAdapted from Stewart.38
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Representative terms from entire chapter:
dietary intake
