An interactive 24-hour recall for assessing the adequacy of iron and

160 Pages·2008·1.05 MB·English

by  Rosalind S. Gibson

8
TECHNICAL MONOGRAPH SERIES
An interactive 24-hour recall
assessing adequacy
for the
iron zinc intakes
of and in
developing countries

Rosalind S. Gibson, Elaine L. Ferguson
c/o International Food Policy Research Institute
2033 K Street, NW, Washington, DC 20006-1002 USA
Phone: [phone] • Fax: [phone] • [email protected]
This manual was initially published as: Gibson, R.S., Ferguson, E.L. (1999) An interactive
24-Hour recall for assessing the adequacy of iron and zinc intakes in developing countries.
ILSI Press, Washington D.C. The original publication was supported in part by the Opportunities
for Micronutrient Interventions (OMNI) program of the United States Agency for
International Development (USAID). The revision was supported in part by HarvestPlus.
HarvestPlus Technical Monographs are designed to provide a forum for HarvestPlus research outputs.
Technical Monographs can be of two kinds:
• state-of-the-art reviews that help to establish and define HarvestPlus research questions or
• “gold standard” procedures to be followed in HarvestPlus research.
HarvestPlus technical monographs are written by recognized experts in the field
and are externally peer reviewed prior to publication.
Rosalind S. Gibson, Elaine L. Ferguson, 2008.
An interactive 24-hour recall for assessing the adequacy of iron and zinc intakes in developing countries
HarvestPlus Technical Monograph 8.
Washington, DC and Cali: International Food Policy Research Institute (IFPRI) and
International Center for Tropical Agriculture (CIAT).
Copyright HarvestPlus, 2008
ISBN 978-0-9818176-1-3
An interactive 24-hour recall
assessing adequacy
for the
iron zinc intakes
of and in
developing countries
Rosalind S. Gibson
Elaine L. Ferguson
International Life Sciences Institute,
Washington DC
1
Preface Users of the manual
The manual has been written as a tool for program
Purpose of the manual planners, experienced health professionals, and nutri-
tionists wishing to measure intakes of iron and zinc
Deficiencies of iron and zinc are a widespread public
and evaluate their adequacy in developing countries.
health concern. Dietary inadequacies of these two
It may also be useful for training nutritionists and
micronutrients are likely to occur in developing coun-
nutritional epidemiologists in developing countries.
tries where staple diets are predominantly plant-based,
For some aspects of the manual, users may require
and consumption of animal protein foods such as red
the specialized assistance of persons with training in
meat, poultry, and fish is often small because of eco-
epidemiology or statistics. The manual contains step-
nomic, cultural and religious constraints. As a result
by-step protocols for training health and nutrition field
the amount of iron and zinc available for absorption
workers in how to design a dietary protocol and to
from such diets is often low. This manual has been
collect valid data on iron and zinc intakes. Emphasis
written as a tool for collecting, analyzing, and inter-
is given throughout the manual to the importance of
preting dietary data on intakes of iron and zinc. Such
collecting the correct type of dietary information to
data are essential for identifying groups at high risk
accomplish the purposes of the study. Depending on
of dietary inadequacies of iron and zinc and for
the dietary protocol adopted, the dietary intake data
implementing intervention programs for combating
obtained could be used to design nutrition intervention
deficiencies of these micronutrients and evaluating
programs targeted at the most vulnerable groups
their effectiveness.
(e.g., pregnant women), estimate the prevalence of
A simplified semi-quantitative dietary method has been inadequate intakes for developing national food poli-
developed by the International Vitamin A Consultative cies (e.g., fortification), examine relationships between
Group and by Helen Keller International to identify dietary indexes for iron and zinc and health and dis-
groups at risk for suboptimal intake and thus defi- ease outcomes, and identify certain food patterns
ciency of vitamin A. However, this method is not associated with inadequate intakes of iron and zinc so
appropriate for assessing intakes of iron and zinc and that effective nutrition education and food-based inter-
evaluating their adequacy in relation to nutrient refer- vention programs can be planned. The manual can
ence levels. To accomplish these objectives, a also be used by experts from a range of disciplines
quantitative dietary method must be used that has the such as rural extension, women’s health, sociology,
ability to measure actual or usual intakes of iron and adult education, epidemiology, and agriculture, as
zinc at an individual or group level, and intakes of well as nutrition and public health. Such an interdisci-
dietary modifiers known to influence the bioavailability plinary team is essential for designing effective
of these micronutrients must also be measured. This nutrition interventions.
manual contains practical guidelines and procedures
for carrying out an interactive 24-hour recall method Organization of the manual
that has been especially modified to collect such infor-
The manual is divided into 11 chapters in the order
mation on rural populations in developing countries.
required to plan, design, prepare and conduct the
Recall data collected for 1 day for each individual can
dietary survey, and then analyze and interpret the data.
be used for assessing or comparing average intakes
Each chapter lists the key objectives at the beginning
of iron and zinc for one or more groups. Alternatively,
and covers a distinct step in the dietary survey method-
recall data collected for 2 or more days on at least a
ology. Within each chapter, there is a series of
sub-sample of individuals can be used to determine
numbered task boxes highlighting the critical steps
the proportion of the population at risk to inadequate
required to accomplish each task. Program planners
intakes of iron and zinc, and to examine associations
and health and nutrition professionals will find it
between dietary and other variables measured on the
helpful to read the background information on each
same individuals.
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An interActive 24-hour recAll for Assessing the AdequAcy of iron And zinc intAkes in developing countries
task whereas health and nutrition field workers can and antinutrients can be calculated (Chapter 8).
simply follow the steps in the task boxes in sequential Nutrient intakes calculated in this way represent the
order. Cross referencing has been incorporated maximum amount available to the body. For iron and
throughout the text to assist the reader and emphasize zinc, however, the amount actually absorbed and uti-
the relationships among chapters. lized by the body can be considerably lower than the
determined values and depends on the bioavailability
Chapter 1 describes the main features of iron and zinc
of these micronutrients. Chapter 9 describes how to
deficiency and emphasizes the importance of defining
estimate the bioavailability of iron and zinc from math-
the purpose of the survey because of its effect on the
ematical models—termed algorithms—based on
study design and sample size. Details of how the
knowledge of the major food sources of iron and zinc
24-hour recall method was modified and validated for
as well as those dietary modifiers known to influence
use with rural populations in developing countries are
their absorption. Finally, Chapter 10 presents ways to
given. Chapter 2 provides some basic guidelines to
evaluate the adequacy of iron and zinc intakes by com-
nonprobability and probability sampling strategies that
parison with nutrient reference levels and Chapter 11
can be used to select the participants, although the
provides a brief guide to the selection of statistical tech-
reader is advised to seek the advice of a person with
niques appropriate for the analysis of the nutrient intake
training in sampling techniques before starting the
data collected. The reader must consult other statistical
survey. Chapter 3 outlines the methods for determining
texts for a more detailed discussion of these techniques.
the sample size and number of recall days, depending
on the study objectives, although readers may wish to Rosalind S. Gibson,
consult with a statistician before finalizing the sample Elaine L. Ferguson,
size. Chapter 4 provides a step-by-step guide on how to Department of Human Nutrition,
prepare for the survey using the interactive 24-hour The University of Otago,
recall method and includes details on fostering com- P.O. Box 56, Dunedin,
munity participation, ethical considerations, and New Zealand.
assembling the necessary equipment. Protocols for
Email: [email protected]
selecting and training the interviewers and pilot testing
[email protected]
the recall method are also included. A detailed discus-
sion of the four stages used to conduct the interactive
24-hour recall is given in Chapter 5. Because the quality
of the food intake measurements collected by the inter-
active 24-hour recall depends on its validity and
reproducibility, both of which vary with the population
group under study, Chapter 6 describes how these attri-
butes can be measured before carrying out the actual
dietary survey. Again, it may be helpful to consult a
statistician before carrying out studies designed to
assess the validity and reproducibility of the interactive
24-hour recall on the study population.
After the interactive 24-hour recall is conducted, the
next stage is to convert the intakes of foods to nutri-
ents by using either a food composition table or a
nutrient database stored on a computer. In many
developing countries a local food composition table
or nutrient database must first be compiled, as
discussed in Chapter 7, before intakes of nutrients
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Acknowledgments
We are particularly indebted to our many colleagues—Dr Peter Bierti, Dr Clare Casey, Dr Maureen Duggan,
Dr Marie Ruel, Dr Christine Hotz, Dr Fiona Yeudall, Margaret Ely, Mary Arimond, Helena Pachon, and others—
who kindly read drafts of this book and suggested improvements. The contributions made by Jennifer Ball,
Shannon Gadowsky, Dr Janet-Marie Huddle, Diane Muwa and the late Haclean Chipingasa during the validation
of the interactive 24-hour recall method in rural Malawi are gratefully acknowledged. We are also very grateful for all the
kindness and support given to us during the development of this dietary method by the late Professor Tim Cullinan and
Mrs T Cullinan, who were working in the Department of Community Health, College of Medicine, University of
Malawi at the time the interactive 24-hour recall method was developed and tested. Dr Elaine Ferguson developed
the 24-hour interactive recall while holding an Overseas Development Associates Award from the Canadian International
Development Agency. We are grateful to Dr Paula Trumbo for her scientific input and Drs Penelope Nestel and
Christine Hotz for their interest in the project.
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An interActive 24-hour recAll for Assessing the AdequAcy of iron And zinc intAkes in developing countries
Table of contents
1 Introduction 9
1.1 A new tool for assessing dietary intakes of iron and zinc 9
1.2 Defining the purpose of assessing intakes 12
2 Selecting the sampling design 13
2.1 Non-probability sampling 13
2.2 Sources of bias in sampling 14
2.3 Probability sampling 14
3 Designing the dietary protocol to meet the study objectives 19
3.1 Defining the study objectives 20
3.2 Preparing to estimate the sample size 20
3.3 Defining the sample size to meet the study objectives 23
4 Preparing for the interactive 24-hour recall 31
4.1 Fostering community participation 31
4.2 Incorporating ethical considerations 33
4.3 Assembling and calibrating equipment 34
4.4 Translating and pretesting 36
4.5 Instructing the field supervisors 37
4.6 Selecting the recall interviewers 38
4.7 Training the interviewers 39
4.8 Pilot testing the interactive 24-hour recall 43
5 Conducting the interactive 24-hour recall 45
5.1 Preparing the respondents for the recalls 45
5.2 Recalling the foods and drinks consumed 46
5.3 Describing the foods and drinks consumed 47
5.4 Estimating portion sizes 49
5.5 Converting portion sizes to weight equivalents 53
5.6 Reviewing the recall interview data 61
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6 Assessing the validity and
reproducibility of the interactive 24-hour recall 63
6.1 Assessing relative validity 64
6.2 Statistical assessment of validity 69
6.3 Assessing reproducibility 72
6.4 Statistical assessment of reproducibility 73
7 Compiling a local food composition table 77
7.1 Compiling the best food composition estimates 77
7.2 Missing values in food composition data tables 79
7.3 Calculating nutrient values of mixed dishes 81
7.4 Checking the quality of the food composition table 82
7.5 Selecting foods for chemical analysis 84
7.6 Food sampling, transport, and handling procedures 85
7.7 Chemical analyses of food samples 89
7.8 International Network of Food Data Systems 92
8 Calculating intakes of nutrients and antinutrients 95
8.1 Compiling weight equivalents for ingredients of mixed dishes from recipes 95
8.2 Coding weight equivalents for ingredients of mixed dishes 95
8.3 Compiling a coding manual and computing nutrient intakes 96
8.4 Manual calculation of nutrient intakes 100
8.5 Preparing the data for statistical analysis 103
9 Estimating available iron and zinc intakes 105
9.1 Algorithms for estimating intakes of available iron 106
9.2 Algorithms for estimating intakes of available zinc 109
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An interActive 24-hour recAll for Assessing the AdequAcy of iron And zinc intAkes in developing countries
10 Evaluating nutrient intakes of groups 115
10.1 FAO/WHO requirements for iron and zinc 117
10.2 IZiNCG requirements for zinc 119
10.3 Incorrect approaches for evaluating nutrient intakes of groups 119
10.4 Full probability approach for evaluating iron intakes 120
10.5 EAR cutpoint method 124
10.6 Using 77 percent of the RNI as a cutoff value 125
11 Statistical analysis of dietary data 129
11.1 Assessing the distribution of the dietary data 129
11.2 Analyses involving the mean intake of a group 130
11.3 Differences between mean intakes of two or more groups 130
11.4 Analyses of proportion at risk of inadequate intakes 131
11.5 Analyses of interrelationships between dietary and other variables 133
11.6 Correcting the effects of within-subject measurement errors 134
Appendices 137
A: Glossary of terms 137
B: Random number table 143
C: Measurement abbreviations and small volume measures 145
D: Specific gravity data for drinks and other liquids 146
E: Suppliers 147
F: Food composition tables 150
G: Zinc, phytic acid, and phytate–to-zinc ([phytate]/[zn]) molar ratios
of some foods and composi te dishes from Ghana and Malawi 154
H: Computer program for calculating the probability of inadequacy 156
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An interActive 24-hour recAll for Assessing the AdequAcy of iron And zinc intAkes in developing countries