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European Journal of Clinical Nutrition (1999) 53, 50±59
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Food consumption of young stunted and non-stunted children in
rural Zambia
JLA Hautvast*1, LJM van der Heijden2, AK Luneta3, WA van Staveren2, JJM Tolboom1 and SM van Gastel2
1
Department of Paediatrics, University Hospital Nijmegen St Radboud, PO Box 9101, 6500 HB Nijmegen, the Netherlands;
Division of Human Nutrition and Epidemiology, Wageningen Agricultural University, PO Box 8129, 6700 EV Wageningen,
the Netherlands; and 3National Food and Nutrition Commission, PO Box 32669, Lusaka, Zambia
2
Objective: The aim of this study was to assess the quality of diet of rural Zambian pre-school children, and to
compare the dietary intake of stunted and non-stunted children.
Design: Cross-sectional study, in which dietary intake was assessed with a 24-h recall method. Height and
weight were measured according to standard procedures.
Setting: Twelve villages in Samfya District, Zambia.
Subjects: Children aged 6 ± 9 months (`infants') and 14 ± 20 months (`toddlers'), attending Mother-and-Child
Health Clinics, were eligible for study. Excluded were: 12 wasted, and 18 for other reasons. In total 106 infants
and 99 toddlers were included.
Results: In infants and toddlers, total daily intake of energy, calcium, iron, and vitamin A was insuf®cient
compared to recommended daily intakes. Only infants had insuf®cient protein intake. Compared to intake from
weaning foods, breast milk was the main source of energy and most nutrients for infants. For toddlers, weaning
foods were more important. Stunted infants and toddlers tended to have lower intakes of energy compared to
non-stunted age-mates. Daily energy intake per kg bodyweight showed no difference between stunted and nonstunted children.
Conclusions: Overall quality of weaning foods was inadequate. Stunted infants and toddlers showed a tendency
of lower energy intakes compared to non-stunted age-mates.
Sponsorship: This study was supported by the Jan Dekker en Dr. Ludgardine Bouwmanstichting, and by
Nutricia Overseas Division, Zoetermeer, the Netherlands.
Descriptors: energy intake; diet; height; preschool children; Zambia
Introduction
In rural Africa the prevalence of linear growth retardation,
also called stunting, among children is generally high (de
Onis et al, 1993). Environmental factors, such as infections,
inadequate food intake, quality of care, and seasonal in¯uences contribute to the development of stunting in a child
(Waterlow, 1992). This may lead to serious functional complications, such as lower mental development, reduced work
capacity in adulthood and increased obstetric risk (GranthamMcGregor, 1995; Haas et al, 1996; Martorell et al, 1992).
In Zambia, a less developed country in south-central
Africa, national ®gures show 40% stunting in children
under the age of ®ve years (Gaisie et al, 1993). A study
in Samfya District, a rural area in the north-east of the
country, showed an increasing prevalence of stunting with
age: 11% from birth to three months of age to 55% from six
to twelve months (Hautvast et al, in press). Because linear
growth retardation in this area occurs in children in an ageperiod when breast milk intake declines and supplementary
*Correspondence: Ms JLA Hautvast, MD, Department of Paediatrics,
University Hospital Nijmegen St Radboud, PO Box 9101, 6500 HB
Nijmegen, The Netherlands. E-mail: [email protected]
Received 16 March 1998; revised 25 July 1998; accepted 18 August 1998
foods are introduced in the child's diet, the relationship of
growth retardation with energy and nutrient intake warrants
further investigation.
Generally, studies on the effect of intake of energy or one
selected nutrient on linear growth retardation have not shown
consistent results (Allen, 1994). Several studies have shown a
positive effect of energy or protein supplementation on linear
growth (Gopalan et al, 1973; Mora et al, 1981; Walker et al,
1991; Schroeder et al, 1995; Neumann & Harrison, 1994).
However, since another study suggested that linear growth
retardation may occur even when intakes of energy and
protein are adequate (Beaton et al, 1992), it is questioned to
which extent micronutrient de®ciencies impair linear growth
of human populations (Allen, 1994). Studies examining the
role of single micronutrients on improvement of linear growth
show con¯icting results. This might be explained by the fact
that not one single micronutrient is responsible for the
development of linear growth retardation, but that poor
quality diets supply insuf®cient amounts of multiple micronutrients (Allen, 1994).
With regard to rural Africa in particular, accurate data
on food consumption are scarce and detailed information is
required to examine the relation with linear growth. The
aim of our study was to describe the quality of diet of rural
Zambian preschool children and to compare the diet of
stunted and non-stunted children.
Food Consumption of Zambian Children
JLA Hautvast et al
Methods
Study area
The study was conducted in Samfya District, a rural area in
the north-east of Zambia, which covers an area of
10 329 km2 with 107 486 inhabitants (Central Statistical
Of®ce, 1990). A large part of the district is situated
adjacent Lake Bangweulu. This lake borders a swamp
area in the south-east, whereas the mainland of the district,
with woodland vegetation and marshy ¯ood plains, is
located on the western side. The main sources of food
and income for the majority of the people are (subsistence-)
farming and ®shing (Gould, 1989). Quality of health care
facilities is poor, illustrated for instance by an infant
mortality rate of 148 per 1000 births in Luapula Province
(Gaisie et al, 1993), in which Samfya District is situated.
Maize, cassava, sweet potatoes, pumpkins, groundnuts,
beans and leafy vegetables are common agricultural products (Moore & Vaughan, 1994). The staple dish in Zambia
is `nshima', a thick porridge made of water and ¯our
(mostly from maize or cassava). It is supplemented with
vegetables, ®sh or meat.
Since laboratory facilities, which were needed for our
main study, were located in the district headquarters, only
villages situated within a 2-hour drive from this location
were included. Thirty-seven health posts (villages with a
Community Health Worker, but otherwise without health
care facilities) are situated on the mainland of the district,
within a two-hour drive from the district headquarters.
From these 37 villages, 12 were selected at random for
recruitment of children in our study.
Design and subjects
In this study a selected group of children of 6 ± 9 months of
age (infants in this study) and 14 ± 20 months of age
(toddlers in this study) were examined in the period
July ± September 1994. The study team consisted of the
principal investigator (JLAH), two quali®ed staff from the
Ministry of Health, and a trained research assistant. All
children of described age groups attending the mobile
Mother-and-Child Health (MCH) clinics in selected villages during the study period were eligible for participation
in the study. Age of the children was either copied from
their clinic card (after verbal veri®cation) or estimated by
comparison with age-mates with known date of birth. For
practical and ethical reasons children who were not accompanied by their mother or caretaker were excluded. HIVinfection is known to be highly prevalent in Zambia
(Fylkesnes et al, 1997), and may therefore have acted as
a confounder in our study on linear growth retardation.
Since an important symptom of established HIV-infection
(AIDS) is severe weight loss, we excluded children who
were wasted (weight-for-height below or equal to 72 s.d.
of the median of the National Center of Health Statistics
(NCHS) reference population) (Hamill et al, 1979). All
communication with the mothers of the children was
carried out by the local staff of the study team, who were
¯uent in the local language, Cibemba. After having
received explanations about the objectives of the study by
a member of the study team, mothers were asked to give
their informed consent for participation of their child in the
study. Out of the initially recorded group of 235 eligible
children, 12 were wasted, 13 were excluded for other
reasons (mother or caretaker absent (5), or refusing to
participate (7), or other reason (1)), and 5 children were
absent during the interview on food consumption. Finally, a
total of 205 children was included in this study, from whom
anthropometric measurements were taken, and a 24-h recall
questionnaire was administered.
Anthropometry
Anthropometric measurements were performed according
to standard procedures (WHO, 1983). Weight of the children, wearing light clothes only, was measured to the
nearest 0.1 kg, using a portable hanging weighing scale
(Salter, England, model 235 6S, 0 ± 25 kg), which was
calibrated daily. Recumbent length of the children was
measured to the nearest 0.1 cm, using a horizontal measuring board with sliding foot piece. Length was measured
with children being barefoot and after removal of any
headgear, and was done by two members of the study
team cooperatively. Weight of the mothers was measured
using bathroom scales with 0.5-kg accuracy. Standing
height was measured to the nearest 0.1 cm using a lengthmeasuring rod with sliding head bar ®xed against a wall.
Members of the study team were intensively trained in
order to minimize inter-observer variation in measurements.
For all children height-for-age- (HAZ), weight-for-age(WAZ), and weight-for-height-Z-scores (WHZ) were calculated using the NCHS reference (Hamill et al, 1979).
Children were classi®ed into two groups according to their
height-for-age Z-score: stunted (HAZ472) and nonstunted (HAZ > 72) (WHO Working Group, 1986).
Mothers of children with a Body Mass Index
(BMI) < 18.5 kg=m2, were considered as having chronic
energy de®ciency (James et al, 1988).
Food consumption
24-h recall questionnaire:
A 24-h recall questionnaire,
adapted for use in the local setting, was used to assess the
food consumption of the children under study (Cameron &
van Staveren, 1988). Consultation of local key-informants
demonstrated that, in general, children start eating from a
shared dish only after the age of 2 ± 3 y; before that age they
are served from a separate dish. Furthermore the traditional
feeding pattern appeared to be uniform throughout the
week.
Mothers were asked to recall all foods and beverages
consumed by their child during the previous 24 hours
(beginning from morning meal on the day before up to
the morning meal on the day of the interview). They were
then asked to both estimate the quantities of the mentioned
foods, as well as to state the ingredients used to prepare the
dishes and to estimate their quantities. To facilitate the
quantity estimates, standardized household measures (18
cups, plates and bowls in total), marked with several levels
to indicate different contents, were provided by the interviewer. Frequency and size of separate foods were
recorded.
Raw ingredients were converted from household measures to weight estimates by taking reference weights,
calculated on the basis of the average of triple weights on
a digital weighing-scale. To estimate the weight of the
cooked dishes, standard recipes were cooked and weighed,
according to reported quantities. For the calculation of the
ratios of the raw ingredients consumed by each child, the
51
Food Consumption of Zambian Children
JLA Hautvast et al
52
weights of the standard recipe most similar to the reported
dish were used.
This questionnaire was pre-tested in comparison with a
weighed observed record (WOR) in a group of 15 children
(aged 14 ± 17 months). For both methods the intake of
energy, protein, fat, carbohydrate, calcium, iron, vitamin
A and vitamin C were calculated and compared. The group
was rather small, therefore no statistically signi®cant differences (a ˆ 0.05) were found between the mean intakes
from the 24-h recall and the WOR (paired t-test). However,
when the differences between the methods were expressed
as a percentage of the WOR, energy, protein, fat, iron and
vitamin A tended to be overestimated with the 24-h recall
in comparison with WOR, whereas intake of carbohydrate,
calcium and vitamin C were relatively underestimated. All
differences between intakes were within 20%, except for
fat intake, which showed 73% overestimation with the 24-h
recall, in comparison with the WOR. This was mainly a
result of reported high intakes of groundnuts. Since consumption of groundnuts for young children is promoted by
local nutrition education programmes, mothers or caretakers may have tended to give socially desirable answers.
In contrast, consumption of food items with low status,
such as cassava, were under-reported. The sample size of
our pre-test was too small to determine reliability of the
recall method. But we estimated within-person variation of
the 24-h recall during the pre-test; this was 1394 kJ for the
energy intake for the repeated 24-h recall. Two members of
the study team were trained to administer this questionnaire. Comparison of the results on intake of energy and
nutrients (as listed above) from both interviewers, as were
derived from the overall study, revealed no signi®cant
differences (Student's t-test, a ˆ 0.05).
Breastmilk volume and composition:
Some of the
mothers of the children studied were living at rather a
large distance from the study site in each village (up to 1 ±
2 h walking). Since the design of our study was not homebased, we decided not to include collection of breast milk
data. We therefore estimated the assumed quantity and
composition of intake from breast milk for those children
who were reported to breast-feed, from the literature. Since
breast-feeding in Zambia is done on demand and since
cessation of breast-feeding is a gradual process, we did not
attempt to differentiate between day- and night-feeding vs
night-feeding only.
Data from a study in neighbouring Zaire (presently:
Demographic Republic of Congo) were used to assess
breast milk volume: for the children who were 6 ± 9
months old, breast milk intake in 24 hours was assumed
to be 553 ml and for the children who were 14 ± 20 months
old, 509 ml (Hennart & Vis, 1980). Values for composition
of breast milk were derived from a study in the Gambia
(West Africa) (Prentice et al, 1986). If no information on a
speci®c nutrient was available, values from George and De
Francesca (1989) were used, unless other studies had
shown a clear relation between nutrient content in breast
milk and maternal nutritional or demographical characteristics. Breast milk in our study was therefore assumed to
contain per 100 ml 313 kJ (calculated by JLAH), 4.2 g fat,
1.3 g protein, 7.7 g lactose, 3.4 mg vitamin C (Prentice et al,
1986), 38 RE vitamin A (Newman, 1994), 21 mg calcium
(Steenbergen van et al, 1981), and 0.05 mg iron (George &
De Francesca, 1989).
Calculation of energy and nutrients
The energy, protein,
fat, carbohydrate, calcium, iron, vitamin A and vitamin C
content of the weaning foods consumed by the children was
calculated. These nutrients were selected because literature
has shown that they are known to be possibly involved in the
linear growth process in children (Allen, 1994; Waterlow,
1994). Furthermore they were selected because reliable
values of these nutrients in food items, as consumed by the
children studied, were available in the literature. Nutrients
were calculated using a Nutrient Calculation program
(KOMEET 2.0, Division of Human Nutrition and Epidemiology, Wageningen Agricultural University, the Netherlands) and a specially developed food composition table for
Samfya District. The food items included in the food composition table were based on interviews with three informants and on the food times eaten by the children under
study. The nutrient contents of the different food items were
based on literature values (West et al, 1988; Leung et al,
1986; Platt, 1962; National Food and Nutrition Commission,
1987). To assess the total weight of the diet of the children,
the weight of all food items consumed was calculated.
To estimate the total energy and nutrient intake of all
children, assumed values of breast milk volume and composition were added to the values of energy and nutrient
intake of the children.
Food groups: To get insight in the dietary sources of the
nutrient intake the different food items were assigned to one
of the following food groups: (1) ®sh; (2) cereals (maize,
millet, rice); (3) meat & dairy; (4) roots & tubers (cassava,
(sweet) potatoes); (5) legumes & nuts; (6) fruits & vegetables;
and (7) a rest group (this group consisted of food items such as
water, sugar, oil, lemonade and biscuits).
Recommended daily intakes:
Recommended daily
intakes (RDIs) for both age groups were calculated for
energy, protein, calcium, iron, vitamin A and vitamin C
intake using FAO=WHO recommendations (FAO=WHO,
1962; FAO=WHO, 1970; FAO=WHO=UNU, 1985; FAO=WHO, 1988). If the original reference provided ®gures of
requirements per kg bodyweight, median weights of the
NCHS reference population were used to calculate the
recommended daily intake. For all nutrients, except
energy, safe level of intake was calculated. For energy
intake average requirement was calculated. Calculation of
the safe level of dietary protein intake was adjusted for
protein digestibility (assumed to be 85%) and amino acid
composition (assumed to be 67%) (FAO=WHO=UNU,
1985). Table 1 presents the calculated RDIs for infants
and toddlers.
Ethics
Ethical approval for this study was obtained from the
Ministry of Health and the National Food and Nutrition
Commission, Lusaka, Zambia.
Data analysis
The software package Epi Info, version 5.01b (Dean et al,
1990) was used to calculate HAZ, WAZ, and WHZ. SPSS
for Windows, version 6.1.4 (SPSS Inc., Chicago IL) was
used for further statistical analyses.
Because the data on energy and nutrient intake were
skewed, the median and 25th and 75th percentiles were
Food Consumption of Zambian Children
JLA Hautvast et al
Table 1 Recommended Daily Intakes (RDI) of energy and nutrient intake for children aged 6 ± 9 months and 14 ± 20
monthsa
Age
RDI for intake of:
6 ± 9 months
Energy (kJ)
Protein (g)b
Calcium (mg)
Iron (mg)
Vitamin A (RE)
Vitamin C (mg)
3200
23
500 ± 600
21
350
20
14 ± 20 months
4850
23
400 ± 500
12
400
20
Source
FAO=WHO=UNU, 1985
FAO=WHO=UNU, 1985
FAO=WHO, 1962
FAO=WHO, 1988
FAO=WHO, 1988
FAO=WHO, 1970
a
For all nutrients except energy, safe level of intake is presented. For energy, average requirement is presented. In the
situation that the original source provided ®gures of requirements per kg bodyweight, median weights of the NCHS
reference population were used to calculate the recommended daily intake.
b
Safe level of dietary protein intake was adjusted for protein digestibility (assumed to be 85%) and amino-acid
composition (assumed to be 67%).
calculated. Mann-Whitney U-test was used for comparison
of energy and nutrient intake between stunted and nonstunted children, and for comparison of proportional contribution of speci®c food groups between stunted and nonstunted children. For the analysis of the contribution of
selected food groups to energy and nutrient intake, breast
milk was also considered as a food group.
Results
Table 2 shows baseline demographic and anthropometric
characteristics of the study population for the two groups:
infants and toddlers. Mean HAZ, WAZ and WHZ scores of
the infants were signi®cantly higher than those of toddlers.
The proportion of mothers with chronic energy de®ciency
(BMI < 18.5 kg=m2) was signi®cantly lower in the infant
group (14%) compared to the toddler group (28%)
(P ˆ 0.02).
Tables 3 and 4 describe the dietary intake of the selected
infants and toddlers. Table 3 shows the estimated median
values of daily energy and nutrient intake derived from
weaning foods only and from weaning foods and the
assumed intake of breast milk together. All infants were
still breast-feeding, whereas nine of the toddlers were not.
Table 2 Baseline demographic and anthropometric characteristics of a
group of infants and toddlers, and anthropometric characteristics of their
mothers, Samfya district (mean (s.d.))
Infants
n
Sex
male (%)
female (%)
Age (months)
minimum
maximum
Height (cm)
Weight (kg)
HAZ
WAZ
WHZ
% mothers with
BMI < 18.5kg=m2 (%)
a
106
47
53
7.3 (0.8)
6.0
8.9
64.4 (2.9)b
7.0 (0.9)b
71.71 (0.98)b
71.27 (0.88)b
0.13 (0.74)b
14a
Toddlers
99
60
40
16.5 (1.7)
13.5
20.0
72.9 (3.5)
8.5 (1.2)
72.37 (1.09)
71.99 (1.02)
70.78 (0.78)
28
Statistically signi®cant difference between infants and toddlers, P < 0.05.
Statistically signi®cant difference between infants and toddlers,
P < 0.001.
HAZ ˆ Height-for-age Z-score; WAZ ˆ Weight-for-age Z-score; WHZ ˆ
Weight-for-height Z-score; BMI ˆ Body Mass Index.
b
Three infants had only consumed water in addition to breast
milk during the period covered by the 24-h recall questionnaire, and one infant had only consumed breast milk.
The mean number of meals consumed, including snacks,
was 2.6 (range 0 ± 5) and 3.0 (range 1 ± 6) for infants and
toddlers, respectively. Intake of energy and nutrients from
weaning foods only was higher in toddlers compared to
infants. In both groups breast milk provided a substantial
part of the energy and nutrient intake. In the group of
infants breast milk adds substantially to the intake of fat,
vitamin A, and vitamin C. In the group of toddlers intake of
fat, vitamin A, and vitamin C was also increased by breast
milk consumption, but relatively less than in the infant
group. As expected, iron intake was hardly increased by
intake of breast milk in both groups. In infants as well as
toddlers, the median energy intake from weaning foods was
mainly derived from carbohydrates (70% and 69%, respectively). Fat contributed 12% and 13%, protein 11% and
15% to the energy intake of weaning foods in infants and
toddlers, respectively. Inclusion of breast milk in the diet of
infants and toddlers showed a considerable increase in
energy percentage derived from fat, with a decrease in
energy percentage derived from carbohydrates. Comparison of the total daily intake of both weaning foods and
breast milk of infants with recommended daily intakes for
that age group, demonstrates that intake of energy, protein,
calcium, iron and vitamin A was too low. Median energy,
protein and vitamin A ranged from 57 ± 80% of RDI.
Median calcium intake was 26% of RDI and median iron
intake 10% of RDI. Intake of vitamin C in infants was
adequate. For the toddler group total intake of energy,
calcium, iron and vitamin A was too low compared to the
recommended daily intake. Median energy and vitamin A
intake were both 70% of RDI. Median calcium and iron
intake were 40% and 42% of RDI respectively. Intake of
protein and vitamin C in toddlers were adequate.
Table 4 shows the proportional contribution of different
food groups to the daily energy and nutrient intake, for
infants as well as toddlers. In infants the main source of
intake of energy and all nutrients, except iron, was breast
milk, as was estimated from literature. In toddlers the
assumed intake of breast milk contributed to > 50% of
the intake of fat, calcium, vitamin A, and vitamin C. For
both infants and toddlers important sources of energy
intake from weaning foods were cereals, and roots and
tubers. For the infants, important sources of protein from
weaning foods were ®sh and cereals, while cereals and
53
Food Consumption of Zambian Children
JLA Hautvast et al
54
Table 3 Estimated daily intake of energy and nutrients at baseline of weaning foods only, as assessed by the 24-h recall, and of weaning foods and the
assumed intake of breast milk (from literature), of a group of infants and toddlers, Samfya district; median (25th ± 75th percentile)
Infants (n ˆ 106)
Intake of:
Total weight food (g)
Energy (kJ)
(kcal)
Protein (g)
energy %
Fat (g)
energy %
Carbohydrates (g)
energy %
Calcium (mg)
Iron (mg)
Vitamin A (RE)
Vitamin C (mg)
Toddlers (n ˆ 99)
WF
WF ‡ BM
WF
WF ‡ BM
256.(153 ± 441)
829.(438 ± 1636)
(197)
6.(2 ± 13)
11.(8 ± 19)
3.(1 ± 6)
12.(8 ± 22)
32.(19 ± 63)
70.(59 ± 83)
28.(13 ± 62)
1.7.(1.0 ± 3.2)
30.(5 ± 82)
2.(0 ± 8)
809.(706 ± 994)
2560.(2169 ± 3367)
(610)
13.(9 ± 20)
9.(7 ± 13)
26.(24 ± 29)
35.(29 ± 40)
74.(61 ± 106)
55.(48 ± 61)
144.(129 ± 178)
2.0.(1.3 ± 3.5)
240.(215 ± 292)
20.(19 ± 26)
499.(355 ± 690)
1804.(1317 ± 2740)
(430)
18.(11 ± 30)
15.(10 ± 22)
6.(3 ± 13)
13.(9 ± 19)
75.(43 ± 108)
69.(56 ± 77)
80.(49 ± 185)
4.3.(2.9 ± 7.1)
87.(46 ± 181)
10.(2 ± 38)
964.(834 ± 1189)
3397.(2910 ± 4333)
(809)
24.(16 ± 37)
13.(9 ± 18)
26.(24 ± 33)
26.(20 ± 31)
114.(79 ± 142)
61.(53 ± 68)
182.(146 ± 289)
4.6.(3.1 ± 7.3)
278.(228 ± 353)
26.(18 ± 54)
WF ˆ weaning foods; BM ˆ breast milk.
Table 4 The proportional contribution of different food groups (assessed with the 24-h recall) and breast milk (estimated from literature) to the intake of
energy and nutrients at baseline of a group of infants and toddlers, Samfya district (%)a
Food groups
Fish
Cereals
Meat & dairy
Roots & tubers
Legumes & nuts
Fruits & vegetables
Restb
Breast milk
Infants (n ˆ 106)
Total weight food
Energy
Protein
Fat
Carbohydrates
Calcium
Iron
Vitamin A
Vitamin C
2
3
19
2
0
7
12
7
0
3
12
11
3
19
2
25
1
0
1
1
3
1
0
1
3
2
0
2
9
2
0
17
7
26
2
5
1
3
6
6
1
1
6
0
0
2
1
1
0
2
4
5
6
12
23
4
2
3
5
1
4
0
0
67
66
56
84
56
76
20
82
82
Toddlers (n ˆ 99)
Total weight food
Energy
Protein
Fat
Carbohydrates
Calcium
Iron
Vitamin A
Vitamin C
4
6
33
6
0
15
16
14
0
6
21
17
7
32
5
31
2
0
1
1
5
2
0
2
3
2
0
4
13
3
1
22
12
23
3
16
1
5
7
11
1
2
6
1
0
4
3
3
0
4
11
10
17
28
36
5
3
5
6
3
5
1
0
45
47
29
67
34
51
7
61
56
a
b
Figures in one row do not always total up to 100%, due to rounding off.
Rest includes amongst others water, sugar, oil, lemonade, biscuits.
roots and tubers were important sources of carbohydrates
and fruit and vegetables major sources of vitamin C. Infants
mainly derived their iron from cereals, and roots and tubers,
while breast milk provided a third source of iron. For
toddlers, in addition to breast milk, important sources of
fat were legumes and nuts, of calcium, ®sh, of vitamin A,
®sh and fruits and vegetables, and of vitamin C, roots and
tubers and fruit and vegetables. The intake of protein in the
toddler group was mainly derived from ®sh, with breast
milk as a second source; carbohydrates were equally
derived from cereals and breast milk. The most important
sources of iron for the toddlers were cereals and roots and
tubers, while breast milk contributed less.
Figures 1a, 1b, and 1c show the proportional contributions of speci®c food groups to the intake of energy, protein
and iron in infants and toddlers, respectively. Figures 1a
and 1b clearly demonstrate that in infants of 6 ± 9 months of
age, the assumed intake of breast milk is the main food and
the most important source of energy and protein. For
toddlers the assumed breast milk intake is clearly still an
important contributor to energy and protein intake. In both
infants and toddlers, cereals and roots and tubers are
important contributors of energy from weaning foods.
Fish and cereals are important contributors of protein
from weaning foods in both groups. Cereals and roots
and tubers are important sources of iron from weaning
foods.
To be able to compare the dietary intake of stunted and
non-stunted children, Table 5 presents median energy and
nutrient intake from weaning food only, in infants and
toddlers. For infants all comparisons were non-signi®cant
(P-values were all > 0.30); for toddlers all comparisons,
except vitamin C, were non-signi®cant (P-value vitamin
A ˆ 0.09; all other P-values > 0.15). In toddlers intake of
vitamin C from weaning foods was statistically different
between stunted and non-stunted children, with higher
Food Consumption of Zambian Children
JLA Hautvast et al
(FAO=WHO=UNU, 1985). Both in infants and toddlers,
the overall results on intake of calcium, iron, vitamin A and
vitamin C in stunted and non-stunted children, were not
consistent with the ®nding of lower energy intake in stunted
children. Total weight of foods, as consumed by infants and
toddlers, showed no difference between stunted and nonstunted children (data not presented). Comparison of the
proportional contribution of the speci®c food groups to the
weight of the consumed weaning food between stunted and
non-stunted children did not show any difference. Figure 2
shows the results of the proportional contribution of speci®c food groups from weaning foods only, to the energy
intake of stunted and non-stunted infants and toddlers. No
statistically signi®cant differences were observed between
the groups, except for the energy intake from the rest food
group of the toddlers.
Discussion
Figure 1 Percentage of energy (1A), protein (1B) and iron (1C) as
derived from breast milk (estimated from literature) and speci®c food
groups (assessed with 24-hr recall), of a group of infants and toddlers,
Samfya district.
Figure 2 Percentage of energy as derived from speci®c food groups
(assessed with 24-hr recall), of a group of stunted (ST) and non-stunted
(NST) infants and toddlers, Samfya district.
values in the group of stunted children (P ˆ 0.012). In
infants and toddlers, stunted children appeared to have,
though not statistically signi®cantly, lower energy intake
from weaning foods compared to non-stunted children.
However, no difference was observed between stunted
and non-stunted children in energy intake per kg bodyweight and no difference was observed in energy percentage distribution. The median total daily energy intake per
kg bodyweight from weaning foods and the assumed intake
of breast milk was 352 kJ and 243 kJ for stunted and nonstunted infants, respectively, and 411 kJ and 373 kJ for
stunted and non-stunted toddlers, respectively. This indicates that for all groups, total dietary energy intake per kg
bodyweight is insuf®cient when compared to the recommended daily energy intake per kg bodyweight, which is
400 kJ and 445 kJ for infants and toddlers respectively
Our study in Samfya District (Zambia) demonstrates that
daily intake of energy, protein, calcium, iron, and vitamin
A from weaning foods is an insuf®cient supplement to the
assumed breast milk intake in infants in order to meet the
requirements needed for their body maintenance and
growth. In toddlers, the diet, including the assumed
intake of breast milk, gives an insuf®cient supply of
energy, calcium, iron and vitamin A. We observed that
stunted infants and toddlers tended to have lower energy
intakes from weaning foods, though not statistically signi®cant, in comparison to non-stunted age-mates. Intake of
other (micro) nutrients did not show a relation with being
stunted.
Children enrolled in this study were recruited through
MCH clinics, and therefore sampling was dependent on
attendance of mothers or caretakers and their children at
these clinics. According to data from the Zambian Ministry
of Health, our study recruited 75 ± 85% of the children in
the speci®c age groups in each catchment area. Furthermore, since both ill and healthy children were equally
absent at the MCH clinics, we assume to have covered a
group of children representative for the mainland of the
district. Since a previous study (Hautvast et al, in press) had
shown that the feeding pattern of children living in the
Bangweulu Swamps of Samfya District was less adequate
in comparison with those living on the mainland, the results
of this study are only valid for the mainland. Since the
mainland of the district is comparable to most rural areas in
Zambia with respect to its ecology, land-use and other
population characteristics, the results from this study may
be extrapolated to other rural areas of Zambia.
Regarding the validity of our measurements, we note
that a source of possible error may be the use of a 24 h
recall method. With respect to this method, information
bias might have occurred, since it depends on information
given by the mother. Because the mothers were not
accustomed to estimating quantities, this was facilitated
by providing a wide variety of commonly used household
measures, all marked with various levels to indicate different contents. However, as was shown in the pre-test, intake
of most nutrients tended to be overestimated with the 24 h
recall in comparison with the WOR; fat intake was overestimated the most. In the present study, however, the mean
intake of fat was almost similar to the mean fat intake
observed with the WOR during the pre-test.
55
Food Consumption of Zambian Children
JLA Hautvast et al
56
Ferguson et al (1994) and Dop et al (1994) showed in
their studies in Ghana and Senegal, respectively, that, the
repeated 24-h recall gives results more similar to the
weighed observation, in comparison with one recall only.
However, they also demonstrated that although the 24 h
recall is not suf®ciently accurate to assess individual food
intake, it is of use in dietary surveys in groups of children.
The relative validity of the 24 h recall at group level applies
to macronutrients and depending on the applied data base,
also to micronutrients. Since the ®rst aim of our study was
to provide descriptive data on the dietary quality of the
children studied, we consider our results on intake of
macro- as well as micronutrients at group level, valid for
description in this paper.
Further, we may query our assumptions on the amount
and composition of breast milk. Prentice et al (1994)
showed that breast milk volume is only negatively affected
by maternal body mass index in situations of (near) famine.
In our study, 14 ± 28% of the mothers had chronic energy
de®ciency (BMI < 18.5 kg=m2), which, though a serious
situation, does not indicate presence of a famine. The
observed difference in the proportion of mothers with
chronic energy de®ciency between infants (14%) and toddlers (28%), may be due to a decrease in maternal weight
during prolonged lactation, which was shown by Adair and
Popkin (1992) to occur after 10 ± 14 months of lactation.
Since our assumptions on breast milk volume were based on
Zairian mothers (Hennart & Vis, 1980), whose height and
weight were fairly similar to our mothers, and are genetically closely related to the ethnic group included in our
study, these estimates will have been acceptably realistic.
However, our assumptions on breast milk content of energy,
protein, fat, lactose, and vitamin C were derived from
Gambian mothers, whose nutritional status was slightly
better compared to our mothers, and therefore may have
been an overestimation compared to reality.
Assuming that the mothers in our population were at risk
for low vitamin A status, we chose to base our estimates of
vitamin A content of breast milk on data from other
developing countries (Newman, 1994). Therefore, if vitamin A status of our mothers was adequate, we may have
underestimated the vitamin A content of breast milk. Since
studies in Kenya and Zaire (Steenbergen van et al, 1981;
Prentice & Barclay, 1991) demonstrated lower ®gures on
calcium content of breast milk compared to developed
countries, we assumed that this would also be applicable
for our situation. However, if in our study conditions
affecting calcium content of breast milk were different
from these studies cited, our estimate of the concentration
of this nutrient in breast milk may have been underestimated.
Our study was performed during the end of the dry cold
season and the beginning of the dry warm season, a period
when food availability is substantially reduced, but not yet
decreased to a minimum (Moore & Vaughan, 1994). Therefore our results on intake of weaning foods re¯ect a
situation of food availability between the annual minimum
and maximum. Furthermore, a study from the Gambia
showed that, in relation to maternal dietary restriction,
breast milk volume and nutrient content are decreased
during the rainy season in comparison with the dry
season (Prentice et al, 1986). Since our study was not
performed during the rainy season, our estimates on breast
milk volume and composition are not confounded by
season.
Total daily energy and protein intake of our infants and
toddlers were similar to intakes of breast-fed children in
Kenya and Uganda of the same age (Steenbergen et al,
1978; Rutishauser, 1974). Comparison with Kenyan toddlers (Calloway et al, 1993; Murphy et al, 1992), who
were, however, not breast-fed, showed that energy, protein,
vitamin A, and iron intake was in a similar range, but fat
intake was higher (50%) in our toddlers, whereas carbohydrate and calcium intake was higher (24 ± 41%) in the
Kenyan children.
Assuming that our estimates on breast milk intake were
correct, energy intake of weaning foods was 640 kJ and
1450 kJ short for infants respectively toddlers to meet the
RDI for energy (Tables 1 and 3). This may ®rstly be
explained by the energy density of the weaning diet,
which was 3.3 kJ=g for infants and 3.7 kJ=g for toddlers.
These densities are low, low ± normal respectively in comparison with the recommended energy density of 3.6 ±
4.8 kJ=g of weaning foods (Cameron & Hofvander,
1983). This was due to the high intake from the food
groups cereals, and roots and tubers, which contain food
products with relatively low energy values, and due to the
overall low fat-energy percentage of the weaning diet.
Another study in Zambia investigating weaning practices
in children aged 6 ± 29 months (Hayes et al, 1994), also
observed low average caloric density per feeding. Secondly, the median weight of each consumed dish was 102
and 180 g for infants and toddlers respectively: this is low
when compared to the maximum volume of 110 ± 200 ml
for infants and 200 ± 300 ml for 1-to-3 y olds respectively,
which can be eaten at one time (Cameron & Hofvander,
1983). Associated with the overall low energy intake,
de®cient intakes of other macronutrients and micronutrients
may be expected, as is also observed in our population.
With respect to the comparison of dietary intake
between stunted and non-stunted children, we again have
to consider the selection procedure. As noted before, the
selection of villages for this study was con®ned to those
situated on the mainland of the district, whereas villages
from the swamp area were not included. However, a
previous study showed similar rates of stunting in preschool children for both areas (Hautvast et al, in press).
Children for this study were recruited through mobile MCH
clinics, and only those who were not wasted were included.
Therefore the population included in this study may have
been less diverse with respect to their nutritional status.
Mean HAZ-scores of the so-called non-stunted infants
and toddlers were below the median of the NCHS-reference
population (both groups 71.12 s.d.) (Table 5). This means
that linear growth of these children was also slightly
retarded, and that they may not have been the optimal
control group. However, the difference in mean HAZscores between the selected study groups of stunted and
non-stunted children was more than 1.5 s.d., which, if the
sample size had been larger, would have been suf®ciently
large to detect possible differences in energy and nutrient
intakes.
In the framework of a larger study, the sample size was
calculated on the basis of detecting a signi®cant difference
in biochemical data between stunted and non-stunted children, which required a number of at least 30 children per
group. However, to detect a signi®cant difference in energy
intake between stunted and non-stunted children, a sample
size of more than 120 children per group would have been
required (with a power of 80% and alpha of 0.05). Due to
Food Consumption of Zambian Children
JLA Hautvast et al
57
Table 5 Anthropometry and estimated daily energy and nutrient intake from weaning foods of a group of infants and toddlers by height-for-age group,
Samfya district; median (25th ± 75th percentile)
Infants
Nutritional statusa
WAZ
HAZ
Dietary intake
Energy (kJ)
(kcal)
Energy=kg (kJ=kg)
(kcal=kg)
Protein energy %
Fat energy %
Carbohydrate energy %
Calcium (mg)
Iron (mg)
Vitamin A (RE)
Vitamin C (mg)
a
Toddlers
Stunted (n ˆ 39)
Non-stunted (n ˆ 67)
Stunted (n ˆ 69)
Non-stunted (n ˆ 30)
71.92 (0.7)
72.72 (0.5)
70.89 (0.8)
71.12 (0.7)
72.42 (0.8)
72.91 (0.8)
71.01 (0.8)
71.12 (0.6)
626.(378 ± 1689)
(149)
96.(61 ± 235)
(23)
10.(8 ± 18)
15.(8 ± 29)
68.(56 ± 83)
29.(11 ± 48)
1.7.(0.6 ± 3.5)
20.(2 ± 95)
1.(0 ± 5)
920.(462 ± 1536)
(219)
112.(69 ± 218)
(27)
11.(8 ± 19)
12.(8 ± 20)
71.(61 ± 84)
25.(13 ± 63)
1.8.(1.0 ± 3.1)
37.(7 ± 75)
2.(0 ± 8)
1708.(1259 ± 2702)
(407)
226.(145 ± 320)
(54)
16.(9 ± 23)
14.(9 ± 21)
68.(56 ± 76)
80.(52 ± 184)
4.3.(2.8 ± 6.6)
99.(66 ± 182)
13.b (2 ± 44)
2121.(1499 ± 2958)
(505)
221.(157 ± 298)
(53)
13.(10 ± 20)
11.(8 ± 16)
75.(60 ± 79)
82.(35 ± 198)
4.4.(3.1 ± 7.2)
60.(30 ± 169)
5.(0 ± 17)
Anthropometry presented as mean (SD); b Signi®cant difference between stunted and non-stunted group; P < 0.05.
the larger day-to-day variation of micronutrient intake, the
group should have been even larger to detect signi®cant
differences in micronutrient intake. Furthermore, if we had
used a repeated 24-h recall in our study, the results on
energy and nutrient intake may have had a lower coef®cient
of variation, and therefore possible differences between
stunted and non-stunted children would have been more
distinct.
We did not expect mothers of stunted children and nonstunted children to answer the 24-h recall differently.
Though volume of breast milk appears to be relatively
unaffected by moderate maternal malnutrition (Prentice et
al, 1994), this is less clear for nutrient content of breast
milk (Abrams, 1991): decreased levels of protein, and fat
soluble vitamins have been observed in malnourished
lactating mothers. In our study, mothers of stunted children
appeared to have more frequent chronic energy de®ciency
(26%) when compared to mothers of non-stunted children
(15%) (statistically signi®cant). Therefore, breast milk
composition of mothers of stunted children may more
often have been of lower quality than of mothers of nonstunted children. Moreover, lower body mass and higher
prevalence of illness in stunted children may result in weak
suckling, which will subsequently reduce milk output.
However, so far no studies have investigated these hypotheses, and we can therefore only speculate that these
assumptions may in¯uence the quantity and quality of
breast milk intake in stunted children.
The observed difference in energy intake of 300 ± 400 kJ
between stunted and non-stunted children, equals about
100 ± 130 ml of breast milk and represents 10% and 8%
of the RDI of infants and toddlers respectively. The lower
energy intake of stunted children will have resulted in
reduced growth and activity levels in comparison with
non-stunted children.
Remarkably, despite no differences in intake of weaning
foods from speci®c food groups in observed stunted and
non-stunted toddlers, daily vitamin C intake from weaning
foods in stunted toddlers was higher in comparison to nonstunted toddlers. We have no other explanation for this
observation other than chance.
In our study, energy intake per kg bodyweight from
weaning foods and assumed intake of breast milk was
de®cient for both stunted and non-stunted infants and
toddlers. Since other studies showed lower gain in length
and smaller attained length for children with lower energy
intakes (Schroeder et al, 1995; Neumann & Harrison,
1994), further adequate length gain of our non-stunted,
and especially our stunted children, may be threatened.
Both ®ndings indicate that catch-up in height growth will
most likely be impossible.
In contrast to our results, an interesting study by Walker
et al (1990) showed equal energy intake, though de®cient,
in stunted as well as non-stunted Jamaican children of 9 ±
24 months, with higher energy intake per kg bodyweight in
stunted children compared to non-stunted. However, in that
study non-stunted children were de®ned as those with a
height above 71 s.d. of the reference, and dietary recalls
were only obtained in children who were not ill. Both
aspects are different from our design which may therefore
explain these different result.
We conclude that despite longstanding preventive health
care programmes, including nutrition education, the quality
and quantity of diet in infants and toddlers of Samfya
District is still insuf®cient. Within a macro-economic context, this points to structural problems at household level,
all affecting intra-household food availability. In view of
the low quality of weaning foods, the observed prolonged
breast-feeding into the second year of life in this environment appears to be a highly recommendable practice,
which should certainly be continued. The high prevalence
of stunting, which is already apparent in infancy and
continues into childhood, may be interpreted as an adverse
consequence of this poor nutritional and environmental
situation. In case the observed de®cit in energy intake in
stunted as well as non-stunted children will persist, an
overall insuf®cient linear growth may be expected. Moreover, for the group of stunted children whose energy intake
tends to be even lower, further deterioration in growth may
occur, making the prospect of catch-up growth impossible.
Contributors Ð JLA Hautvast, WA van Staveren and JJM Tolboom
designed the study, and are the guarantors for the integrity of the article
as a whole. All authors contributed to the preparation of the manuscript.
JLA Hautvast was the principal investigator, who managed the data-
Food Consumption of Zambian Children
JLA Hautvast et al
58
collection, was responsible for the statistical data-analysis, wrote the ®rst
drafts and the ®nal version of the manuscript. LJM van der Heijden codesigned the dietary methods, and supervised the dietary data-collection.
AK Luneta contributed to the design of the study and provided information
on dietary habits in the country of study. WA van Staveren co-designed the
dietary methods, and contributed to the interpretation of the results. JJM
Tolboom contributed to the interpretation of the results. SM van Gastel
performed a substantial part of the data-collection and was responsible for
the dietary data-calculation.
Acknowledgements Ð The authors wish to express their gratitude to
individuals of the Ministry of Health and the National Food and Nutrition
Commission for their assistance in the facilitation and implementation of
the study. Special thanks are extended to Mr J Mpundu, and Ms E Semba
for the administration of the questionnaires. UNICEF-Zambia is acknowledged for their advice and material support. We gratefully acknowledge
Ms AWEM van den Wijngaart for her assistance in the pre-testing of the
questionnaire. We wish to thank Dr MA van't Hof and Mr J Burema for
their statistical advice, and Prof Dr LAH Monnens for reviewing the
manuscript.
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59