Deficiency of Micronutrients Clinical Trial
Official title:
Food Consumption and Iron Status Survey in Two Provinces of Rural Burkina Faso
Sorghum is the primary source of food for more than 300 million people in arid and semi-arid
regions of Africa. The grain is one of the few crops that grow well in arid climates, but
has a low content in most essential nutrients and is difficult to digest. The African
Bio-fortified Sorghum (ABS) Project, a consortium of nine institutions led by Africa Harvest
Biotech Foundation International, is working to develop new varieties of sorghum that are
easier to digest and contain lower levels of phytates to improve the bioavailability of
micronutrients.
In order to determine their target levels, the ABS project needs reliable information on
current levels of micronutrient deficiency and consumption patterns of sorghum and nutrients
of interest, e.g. iron, zinc, and vitamin A in women and preschool children, which are not
currently available in Burkina Faso.
A background nutrition survey among children and women, comprised of two rounds, one in the
lean season (July - August) and one in the harvest season (November - January), has been
conducted to provide quantitative estimates of sorghum, vitamin A, iron and zinc intakes by
women and young children from two rural provinces of Burkina Faso. The survey also had a
biochemical component which included blood collection and analysis for indicators of
deficiency for vitamin A, iron and zinc. Other important components of this study included
anthropometric measurements, household and child morbidity questionnaires, and collection of
sorghum samples for analysis of phytate, vitamin A, iron and zinc content.
Objectives of the study
The main objectives of the study were:
- To determine iron, zinc, polyphenolic compounds, and phytate content in raw sorghum
grains and cooked sorghum based dishes;
- To estimate the prevalence and level of sorghum consumption in women and preschool
children;
- To determine the percent contribution of Sorghum to total vitamin A, iron and zinc
intake;
- To assess the prevalence of inadequate intakes of vitamin A, iron and zinc as defined
by the cut-point method using Estimated Average Requirements for women and children
according to sex and age;
- To determine the prevalence of micronutrient deficiencies using international (WHO)
cut-offs for serum retinol, serum ferritin and serum zinc.
Two secondary methodological objectives were added because of their scientific interest and
of their potential practical implications:
- To assess the performance of dietary diversity scores in reflecting adequacy of
micronutrient intakes;
- To assess the performance of questionnaires on expenditures at the household level in
estimating food consumption of household members.
Setting
The study has been conducted in the "Boucle du Mouhoun" and "Centre-Ouest" regions located
in Western Burkina Faso. These regions were selected based on a combination of health,
agriculture, living conditions and demographics criteria, which included data on sorghum
production, household consumption and prevalence of malnutrition.
The province of Sourou in the "Boucle du Mouhoun" region and the province of Sanguié in the
"Centre-Ouest" region were chosen purposely based notably on available information on
sorghum production or consumption and on some of the principal investigators general
knowledge of the field.
Study design
It was a cross-sectional survey in two rounds: a first round during the lean period
(July-August 2010) characterized by very low food availability in Burkina Faso; and a second
round during the period of greatest food availability, immediately after harvest (November
2010-January 2011). To enhance the study power, the same individuals were surveyed during
these two rounds.
The study had two main components: the "food consumption" component and "lab analysis"
component.
The food consumption component included:
- A quantitative 24 hour recall of dietary intake on a random sample of preschool
children aged 3-5 y and their mothers
- A qualitative dietary diversity questionnaire for both the children and the mothers,
administered on the same day as the 24-h recall but by a different enumerator
- A repetition of the 24 hour recall on non consecutive days using a randomly selected
subsample of approximately one third of the original sample
- A questionnaire about income and expenditure on a subsample of approximately one other
third of the households (i.e. not the households having a repetition of the 24-h
recall)
- Anthropometric data (weight, height and MUAC) collected for all children and their
mothers
- A socio demographic questionnaire and morbidity recall for all children and their
mothers
The laboratory component included:
- Collection of blood samples from a randomly selected subsample of mothers and children
(one third of the original sample) for vitamin A, iron and zinc biochemical indicators
as well as haemoglobin and acute phase proteins (C-reactive protein and
alpha-1-glycoprotein as markers of inflammation); this blood sampling took place only
during the second round of the survey (November 2010 - January 2011).
- Collection of raw sorghum and cooked sorghum dishes samples for determination of iron,
zinc, polyphenolic compounds and phytate content; food sample collection took place
during the two rounds.
Target population
Women and preschool children were selected because their micronutrient requirements are
highest due to their needs for reproduction and growth, respectively. The age range for
targeted preschool children was 36-59 months for several reasons: Firstly, we wanted to be
sure to exclude breastfed children since the measure of breast milk intakes are very
complicated to implement on the field; Secondly, starting at the age of 36 months, most
children are used to eating from the common family dish and this made the recall easier,
while keeping the number of individual recipes lower. Thirdly, venous puncture was less
problematic for children aged 36 months or more.
Sample size for dietary intake: using food consumption data from a survey conducted among
women of reproductive age in Ouagadougou, one determined that for a reasonable hypothesis of
a coefficient of variation of sorghum intakes of 0.60, with a precision of 0.10, a type I
error of 0.05 and supposing a design effect of 1.5, the required sample size was 207
subjects. Finally we decided to set the sample size at 240 households per province and per
round, to account for lost of follow-up. The repetition of 24 hour recalls was perfomed on 3
out of 8 subjects.
Sample size for the biochemical indicators: Given a type I error of 0.05, we calculated
hypothetical sample sizes for different values of the prevalence of micronutrient
deficiencies (30, 40 or 50%) and different desired precisions (either 0.05, 0.075, 0.10,
0.125 or 0.15) and also taking into account different hypotheses about the survey design
effect. A huge sample size would have been required to get a precision less than 0.10,
depending on the design effect, if data had to be representative at the individual level
(women and children) in each province. According to constraints in logistics and financing,
we decided to limit the sample size to 90 women and 90 children in each province.
Sample size for sorghum analysis: Five samples of each type of sorghum (red, white, hybrid)
and 5 samples of each type of sorghum-based food (paste, gruel) were analysed for each
province at each round. This adds up to 30 samples of each class of sorghum and of
sorghum-based food in each province at each round, then a total of 120 food samples.
However, given the potentially high variability of nutrient density in some food samples,
each analysis was performed on a pool of 6 samples of the same type, coming from close
villages belonging to a common health area.
Location and sampling procedure
In each province, a multistage sampling procedure was used:
- Firstly a list of all health centres in each province was made and the population size
for corresponding health areas was obtained from heath districts and/or administrative
data. Five centres were randomly selected in each province, with a probability
proportional to size (of population in health areas).
- The same proportional to size sampling technique was used to select 6 villages in each
health area, leading to a total of 30 villages.
- Finally, 8 households were selected in each village, from the list of eligible
households which was obtained by a census performed by enumerators a few days ahead of
the data collection.
- Among the 8 HH included a further random selection was made to determine which of them
took part in the repetition of 24-h recall (3 HH) and in blood sampling (3 HH).
Data Collection
Anthropometric data were collected for all study participants (mothers and children) using
standard WHO procedures Food intake was assessed by 24-H recall using the multiple pass
method. A set of standard recipes was prepared (by observation) and other individual recipes
were investigated directly. A local Food Composition table was built by compliling
information from available food composition tables (from Mali, FAO, USDA).
The food sampling was done in households selected for this purpose in each village. In these
households, about 1 kg of sorghum (white or red) was sampled in clean new polyethylene
plastic bags to avoid any contamination. For meals sampling, the selected households were
asked to prepare a sorghum based dish (tô or porridge) according to their habits. All
samples were put into icebox for transportation to the IRSS laboratory where extraction and
analyses was done.
The blood collection was conducted at health centres in cool places with subdued light and
conducted by a trained health professional. Care was taken to avoid any contact between the
samples and surrounding dust, sweat, or other possible exogenous sources of contamination.
The sampling technique was a venous puncture of 10 mL of blood.
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Observational Model: Cohort, Time Perspective: Cross-Sectional
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