F&N Bulletin Vol 23 No 1b - United Nations University

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N. Omidvar et al.
of sensitivity, than a targeted intake assessment similarly
validated among preschool children in rural
Thailand [7]. Infection was more likely to influence
serum retinol levels among the Thai children than
in the present sample, whereas intake per se is more
important in the present sample of Iranian women.
Discussion
The purpose of this pilot study was to design and
validate a short food-frequency questionnaire for
screening women’s vitamin A status. A 20-item short
food-frequency questionnaire was developed. Validity
and reliability tests indicate that the questionnaire is
relatively valid and reliable for the purpose of identifying
women at risk for vitamin A deficiency as indexed
by serum retinol level. The correlation between short
food-frequency questionnaire estimates of dietary
vitamin A intake and serum concentration of retinol is
similar to that reported for children [6, 13, 14] and for
pregnant and lactating women [17]. These findings
stand in contrast to observations in populations of
vitamin A-sufficient adults in which no correlations
or only weak relationships between serum retinol and
intake were found [18–20].
The findings of the present study indicate a lack
of correlation between estimates of vitamin A intake
by recall over a 48-hour period and serum retinol
concentrations. This observation is consistent with
previous studies demonstrating higher reliability of
intake estimation by food-frequency questionnaire
than that by 24-hour recall with respect to vitamin A
status. Serum vitamin A levels are a function of longterm
intake of vitamin A-containing foods. Therefore,
short-term measurement of vitamin A intake is subject
to fluctuation and does not reflect the risk of
deficiency.
Two items rather specific to this population emerged
from this analysis. The most striking is the importance
of nuts in the diet. Although nuts are relatively low in
provitamin A, their regular intake by the study subjects
makes their contribution to vitamin A intake significant.
The second is the importance of green leaves of
the type utilized in other cuisines as herbs (parsley,
dill, cilantro, and others). These are eaten regularly and
in large quantities, are grown in household gardens to
assure a steady supply for the table, and are basic to
Iranian dietary habits.
A previous study in Ilam Province of Iran showed
a lack of correlation between frequency of intake of
vitamin A-containing foods, according to the Helen
Keller International short food-frequency questionnaire,
and serum retinol in preschool children [16].
This questionnaire allows for modification of some
of the food items based on the dietary pattern of
the population under study. The modified version of
the questionnaire applied in the Ilam study demonstrated
low internal consistency. The lack of association
observed between the food-frequency questionnaire
estimates of vitamin A intake and serum retinol in the
Ilam study may have arisen from differences in study
design, populations, and specific food items included
in the questionnaire as compared with the core foods
eaten, affecting the overall validity and reliability of
the questionnaire.
The short food-frequency questionnaire designed
for this study represents one of the first attempts to
develop standardized dietary tools for the Iranian
population. Application of a biochemical indicator
provided an independent measurement for assessment
of the validity of the questionnaire for screening
vitamin A status. Further study is needed to evaluate
the accuracy and applicability of the questionnaire in
different communities in the area and whether it could
be successfully utilized by auxiliary health workers
with minimum training.
Acknowledgments
We thank the Office of Research Affairs in the Ministry
of Health and Medical Education, Islamic Republic
of Iran, for financial support; the Human Nutrition
Laboratory, National Nutrition and Food Technology
Research Institute of Iran for measurement of serum
retinol; the Faculty of Nutrition and Public Health
at Tabriz University of Medical Sciences; the health
workers of Marand District; and the women who
participated in the study. This paper was presented in
part at the International Conference on Dietary Assessment,
Tucson, Arizona, USA, September 17, 2001.
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