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4 UR106 NALIS, Institut de Recherche pour le Développement, 34394 Montpellier, France; 5 Doctoral School 393, Université Pierre et Marie Curie, 75005 Paris, France; 6 Food Consumption and Nutrition Division, International Food Policy Research Institute, Washington, DC 20006; and 7 Program in International Nutrition and Community Nutrition, University of California, Davis, CA 95616
* To whom correspondence should be addressed. E-mail: moursi{at}mpl.ird.fr.
| ABSTRACT |
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2 best predicted low dietary quality (MMDA <50%), with 64% sensitivity, 82% specificity, and 22% misclassification. Imposing a 10-g minimum increased misclassification (30%). These results support the growing evidence of the usefulness of dietary diversity to predict dietary quality, and among infants and young children more specifically.
| Introduction |
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Dietary diversity has been shown to be associated with increased nutrient adequacy of children and adults in developed countries (3,4). Similar results showing that higher dietary diversity was associated with increased nutrient intake or better child nutritional status were also found in developing countries (5–10). A review of studies conducted in developing countries (11) concluded that further research was needed to refine dietary diversity scores (DDS)8 and to assess their utility to accurately reflect diet quality in young children.
Recent validation studies have provided new evidence on the relationship between DDS and micronutrient adequacy or intake of 1- to 8-y-old non-breast–fed (non-BF) children (12–14). These studies showed that DDS were positively correlated with micronutrient intake (13,14) and density (12). A DDS score of 4–5 (out of a maximum of 9–10) was found to be the best compromise between sensitivity and specificity for detecting low micronutrient adequacy, but there was no clear preferred score for high adequacy. Furthermore, in the Philippines (12), the authors assessed the effect of imposing a 10-g minimum food group requirement for the calculation of DDS and found that it improved the score's correlation with measures of micronutrient adequacy and the score's ability to predict low adequacy with reduced misclassification.
Although these studies have helped determine the utility of DDS for non-BF children, the utility of DDS for breast-fed (BF) and non-BF infants during their first year of life remains unknown. Moreover, to our knowledge, the key question of the optimal selection of food groups for the calculation of the DDS has not yet been explored.
This study addresses these questions by comparing how diversity scores (based on different food groups with or without portion size restrictions) relate to micronutrient density of the diets of 6- to 23-mo-old children in urban Madagascar.
| Materials and Methods |
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Sample selection and study design. The study was conducted within the Nutrimad project (16). The study population was composed of mother-infant dyads in the districts of Sahalava and Antsororokavo, Fianarantsoa, Madagascar. On the basis of information on population size, sociodemographic factors, and prevalence of child malnutrition, these 2 districts had characteristics similar to other poor urban districts of Fianarantsoa.
Children aged 0–18 mo who met the following eligibility criteria were invited to participate: born in the districts; absence of illness requiring hospitalization and of malformation affecting anthropometric measurements; no intention of moving away in the next 6 mo. A total of 702 eligible infants were included, 14 mothers refused to participate, and 51 children subsequently dropped out. The study was conducted for 7 mo (April–October 2004) and comprised 3 visits at 3-mo intervals (±15 d).
This analysis was conducted on children aged 6 mo or more at any visit and for the purpose of this analysis, the same child at different visits counted as separate observations (i.e. the unit of analysis was the child x visit). The total number of available child-days was 1667.
Data collection and analysis. Details of anthropometric measurements were previously described (17). Dietary intake of infants was estimated using a quantitative maternal 24-h recall. Portion sizes and quantities of ingredients used to prepare mixed recipes were determined using standardized household measures (18). Visual aids were available to assist respondents in accurately reporting portion sizes.
A food composition table was compiled using values from the FAO's World Food Dietary Assessment System (version 2; University of California) and the USDA nutrient database release 18 (19).
Construction of DDS.
Four different DDS were used. Two DDS summed a total of 8 possible food groups (DDS8 and DDS8-R). The 8 food groups were: grains, roots, and tubers; legumes and nuts; dairy products; flesh foods (meat, fish, poultry, and liver/organ meats); eggs; vitamin A-rich fruits and vegetables (>130 retinol equivalents/100 g); other fruits and vegetables; and fats and oils. A score of 1 was assigned if a child ate 1 or more foods from a given food group and 0 if not. These values were then summed up for all food groups with a range of 0–8 for DDS8 and DDS8-R. For DDS8, a food group scored 1 if at least 1 g was consumed. For DDS8-R, a food group was counted only if at least 10 g were consumed, except for fats and oils, for which the cut-off of
1 g was used. Two additional scores were calculated after excluding the fats and oils group (DDS7 and DD7-R) using the 1-g and 10-g minimum cut-offs (range 0–7).
Mean micronutrient density adequacy. The quality of the diet was defined on the basis of micronutrient density (amount per 100 kcal or 418 kJ of food) because of the variability in breast milk intake among children. Average breast milk intake was assumed for BF children (20) and recommended nutrient intakes (RNI) were taken from FAO/WHO recommendations (21), except for calcium (22) and zinc (23).
For BF infants aged 6–11 mo, 9 key micronutrients were considered (vitamin A, thiamin, riboflavin, vitamin B-6, folate, vitamin C, calcium, iron, and zinc) (20). For BF children aged 12–23 mo and for all non-BF children, vitamin B-12 was also included, for a total of 10 key micronutrients. To derive the desired nutrient density values, the estimated amount contributed by breast milk (20) was subtracted from the RNI for each micronutrient. The individual micronutrient density adequacy was calculated as the percentage of the desired nutrient density specific for age and breast-feeding group (15). The mean micronutrient density adequacy (MMDA) was calculated as the mean of all micronutrient density adequacies, with each capped at 100%. Dichotomous variables were constructed to identify child-days with low MMDA (<50%) and better MMDA (
75%).
Statistical analysis.
Correlation and regression were used to assess the strength of the relationship between DDS and MMDA. Interaction terms testing consumption of infant formula or fortified foods were not significant at P
0.10. We tested for linear trends by adding a quadratic term to the regression equation (DDS2); a significant coefficient for this term was considered as an indication of deviation from linearity. We used cross-sectional time-series regression models to adjust the correlation coefficients of the relationship between dietary diversity and MMDA for multiple observations from the same child and results were unchanged.
We calculated the area under the curve (AUC) for the receiver operating characteristic relationship and tested whether it differed significantly from the null value of 0.5; a null value would indicate that a given DDS has no predictive value. The performance of the different diversity scores was compared by testing differences in AUC, with greater AUC indicating better performance. Sensitivity and specificity analysis (24) was conducted to compare the utility of diversity scores for correctly identifying cases with low or better MMDA. Statistical analyses were conducted using Stata 8.2 (StataCorp); P-values < 0.05 were considered significant.
Ethics. The study protocol was approved by the health department of Fianarantsoa province. Verbal informed consent to participate was obtained from all subjects.
| Results |
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Breast-feeding is common in Madagascar and most children (79%) were still breast-fed during their 2nd y of life (Table 1). The prevalence of stunted children was high across all age groups. By contrast, wasting was low at all ages. Mean caretaker age was 28 y and 42% had a low level of schooling. The sample was almost equally composed of boys (51%) and girls (49%).
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75% was low among BF infants 6–8 mo of age but was higher for older children and for those non-BF. Patterns of food consumption varied at different DDS8 scores (Table 3). Grains, roots, and tubers were the main food source at a DDS of 1. Other fruits and vegetables were consumed by more than one-half of the children at a DDS of 2 and >90% at a score of 4. Fats and oils were commonly consumed starting at diversity scores of 3 and higher. Flesh foods were consumed by at least one-half of the children at DDS of 4 and higher, whereas for legumes and nuts, dairy products, vitamin A-rich fruits and vegetables, and eggs, this only occurred at DDS of 6 and higher. Patterns of food group consumption were similar for DDS8-R, DDS7, and DDS7-R.
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For BF children 6–23 mo of age, using DDS7 for predicting low MMDA, a cut-off point of
2 food groups produced the best trade-off between sensitivity (64%) and specificity (82%) while keeping misclassification at 22% (Supplemental Table 2). The same cut-off also offered the best compromise for DDS7-R; relative to DDS7, sensitivity (82%) was improved at the expense of specificity (67%), but misclassification was higher (30%).
There was no clear cut-off for predicting better MMDA. No acceptable trade-off between sensitivity and specificity could be found using DDS7-R. The trade-off between sensitivity and specificity using DDS7 occurred at the cut-off of
4, but misclassification was high (31%).
| Discussion |
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The sensitivity/specificity analysis showed that, for BF children, DDS predicted low micronutrient adequacy (MMDA <50%) with reasonable sensitivity and specificity. A cut-off of
2 food groups resulted in moderately low misclassification, especially with the 7-group DDS (without a 10-g restriction), while achieving reasonable balance between sensitivity and specificity. No clear cut-off using MMDA
75% was found.
Comparison with other studies. Correlation coefficients for the association between DDS and diet quality in non-BF infants in our study differed from those of other validation studies (12–14). This is explained by several methodological differences, the first of which was the use of other measures of diet quality such as mean adequacy ratio (14) and mean probability of adequacy (12,13). Calculation of mean probability of adequacy is based on the estimated average requirements and the SD of the requirement distributions, not the RNI; estimated average requirements/SD are not available for most micronutrients for infants <12 mo old, so we did not take this approach. Also, because we did not have total breast milk intake data (and thus total nutrient intake), we used micronutrient densities (per 100 kcal, 4184 kJ) to characterize diet quality. Despite differences in magnitude of coefficients, all studies, including ours, found a positive correlation of DDS with measures of diet quality and/or quantity, thus confirming the usefulness of DDS to reflect diet quality.
Choice of food groups to include in DDS. Earlier DDS included fats and oils (12–14,25,26) and we therefore included this group in 2 scores. However, we also explored whether the indicator could be improved by excluding this group, because, with the exception of red palm oil, fats and oils generally do not contribute substantially to intake of the "problem" micronutrients. DDS7 and DDS7-R performed more favorably than DDS8 and DDS8-R in all analyses, achieving stronger correlations, higher AUC, and better balance between sensitivity and specificity. There are arguments against excluding fats and oils from diet quality indicators, particularly in light of recent findings demonstrating the role played by essential fatty acids in infant growth (27). These findings might point to the necessity to incorporate essential fatty acids into measures of diet quality and to accord them the same level of attention as to key micronutrients. Alternatively, fats and oil could be measured as a separate indicator of diet quality and kept independent from the DDS.
Imposing a 10-g minimum or addressing portion size in a DDS? For non-BF infants, imposing a 10-g minimum quantity increased correlation coefficients, especially among non-BF children. However, this did not translate into consistent improvements in classifying children into those with low and those with better MMDA. Although sensitivity increased with the use of the 10-g minimum, this has to be balanced against the impracticality and additional difficulties that this poses in the field. Also, increased sensitivity was accompanied by higher misclassification and reduced specificity (i.e. more false positives). If the indicator is used for targeting, false positives result in higher costs. Therefore, the usefulness and feasibility of these refinements will ultimately depend on time and resources available and the final use that will be made of the indicator.
Using a DDS for assessing "low" and "better" diet quality. This study contributed to a larger, 10-site study aimed at identifying population-level indicators for assessing young child feeding (28) and potentially for geographic targeting of programs. For these purposes, it is reasonable to aim for a balance between sensitivity and specificity, while also considering overall misclassification. Results from 1 site should not be used to make decisions about universal indicators. However, our results can serve to illustrate the trade-offs and results that are relevant for this site.
Our findings indicate that DDS are better at identifying children with low micronutrient adequacy rather than those with high adequacy. This is partly due to the fact that the requirements for certain micronutrients such as iron are so high (particularly for infants <1 y) that no children in our sample actually achieved 100% MMDA with their usual diet and only 30% achieved an MMDA
75%.
Limitations. One limitation of this study is the use of 1 24-h recall to assess micronutrient density adequacy as well as uncertainties about quantification of amounts of foods consumed and nutrient composition data. Though precautions were taken during the collection and analysis of data, there are inevitably some errors, which are inherent to this type of research. Another limitation is the use of 24-h recall data to calculate DDS as opposed to questions specifically designed for field use. However, one objective of the exercise was to develop the simplest possible meaningful DDS to minimize potential difficulties with recall. Although field testing is needed, recall may be facilitated by the broad food groups and lack of need for information on quantities. A mother or caregiver would only need to report (yes/no) whether her infant ate any food based on grains, etc. In addition, dietary diversity has been consistently associated with dietary quality (often measured as nutrient adequacy) despite differing methods and scoring systems (11), confirming that the association is robust.
In sum, this study showed that DDS are useful proxies of micronutrient density of foods consumed by BF and non-BF infants. The performance of DDS could be improved by omitting the fats and oils food group, yielding stronger correlations with micronutrient density and better balance between sensitivity and specificity. Applying a 10-g minimum did not substantially improve the performance of DDS in identifying children with low or high micronutrient adequacy and thus might not be warranted, given that it adds considerable complexity to data collection. These results add to the growing useful evidence base for the selection of indicators, field testing, and further dialog toward consensus.
| FOOTNOTES |
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2 Author disclosures: M. Moursi, M. Arimond, K. Dewey, S. Trèche, M. Ruel, and F. Delpeuch, no conflicts of interest. ![]()
3 Supplemental Tables 1 and 2 and supporting material are available with the online posting of this paper at jn.nutrition.org. ![]()
8 Abbreviations used: AUC, area under the curve; BF, breast-fed; DDS, dietary diversity score; DDS7 and DDS8, dietary diversity scores based on 7 and 8 food groups, respectively; DDS7-R and DDS8-R, dietary diversity scores with 10g minimum consumption restriction; MMDA, mean micronutrient density adequacy; non-BF, non-breast–fed; RNI, recommended nutrient intake. ![]()
Manuscript received 4 June 2008. Initial review completed 17 July 2008. Revision accepted 9 September 2008.
| LITERATURE CITED |
|---|
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1. Sanghvi TD. Complementary feeding: report of the global consultation, and summary of guiding principles for complementary feeding for the breastfed child. Geneva: WHO; 2002.
2. Piwoz EG, Huffman SL, Quinn VJ. Promotion and advocacy for improved complementary feeding: can we apply the lessons learned from breastfeeding? Food Nutr Bull. 2003;24:29–44.[Medline]
3. Kant AK. Indexes of overall diet quality: a review. J Am Diet Assoc. 1996;96:785–91.[Medline]
4. Kant AK. Dietary patterns and health outcomes. J Am Diet Assoc. 2004;104:615–35.[Medline]
5. Arimond M, Ruel MT. Dietary diversity is associated with child nutritional status: evidence from 11 demographic and health surveys. J Nutr. 2004;134:2579–85.
6. Ferguson EL, Gibson RS, Opare Obisaw C, Osei Opare C, Lamba F, Ounpuu S. Seasonal food consumption patterns and dietary diversity of rural preschool Ghanaian and Malawian children. Ecol Food Nutr. 1993;29:219–34.
7. Hatloy A, Torheim LE, Oshaug A. Food variety–a good indicator of nutritional adequacy of the diet? A case study from an urban area in Mali, West Africa. Eur J Clin Nutr. 1998;52:891–8.[Medline]
8. Onyango AW. Dietary diversity, child nutrition and health in contemporary African communities. Comp Biochem Physiol A Mol Integr Physiol. 2003;136:61–9.[Medline]
9. Sawadogo PS, Martin-Prevel Y, Savy M, Kameli Y, Traissac P, Traore AS, Delpeuch F. An infant and child feeding index is associated with the nutritional status of 6- to 23-month-old children in rural Burkina Faso. J Nutr. 2006;136:656–63.
10. Tarini A, Bakari S, Delisle H. La qualité nutritionnelle globale d'enfants nigériens se reflète sur leur croissance. Sante. 1999;9:23–31.[Medline]
11. Ruel MT. Operationalizing dietary diversity: a review of measurement issues and research priorities. J Nutr. 2003;133:3911S–26.
12. Daniels MC, Adair LS, Popkin BM, Truong YK. Dietary diversity scores can be improved through the use of portion requirements: an analysis in young Filipino children. Eur J Clin Nutr. 2007;Epub:1–10.
13. Kennedy GL, Pedro MR, Seghieri C, Nantel G, Brouwer I. Dietary diversity score is a useful indicator of micronutrient intake in non-breast-feeding Filipino children. J Nutr. 2007;137:472–7.
14. Steyn NP, Nel JH, Nantel G, Kennedy GL, Labadarios D. Food variety and dietary diversity scores in children: are they good indicators of dietary adequacy? Public Health Nutr. 2006;9:644–50.[Medline]
15. Arimond M, Cohen R, Dewey KG, Ruel MT. Developing and validating simple indicators of complementary food intake and nutrient density for infants and young children in developing countries: protocol for data analysis. Washington, DC: The Food and Nutrition Technical Assistance Project and Academy for Educational Development; 2005.
16. IRD/GRET/LABASAN. Nutrimad: Programme de lutte contre la malnutrition à Madagascar, une composante du programme Nutridev GRET/IRD; 2006 [cited 2008 Apr 2]. Available from: http://www.gret.org/pays/result_long.asp?pays=121&cle=825.
17. Moursi MM, Martin-Prével Y, Eymard-Duvernay S, Capon G, Maire B, Delpeuch F. Assessment of child feeding practices using a summary index: stability over time and association with child growth in Urban Madagascar. Am J Clin Nutr. 2008;87:1472–9.
18. Dop M-C, Gomis M-C, Gourdon M, Lesauvage S. Outils d'enquêtes alimentaires par entretien: élaboration au Sénégal. Paris: IRD Editions; 2003.
19. USDA. USDA national database for standard references, release 18; 2005 [cited 2005 Oct 25]. Available from: http://www.nal.usda.gov/fnic/foodcomp.html.
20. WHO. Complementary feeding of young children in developing countries: a review of current scientific knowledge. WHO/NUT/98.1. Geneva: WHO; 1998.
21. FAO/WHO. Vitamin and mineral requirements in human nutrition. Rome and Geneva: FAO and WHO; 2002.
22. IOM. Dietary reference intakes for calcium, phosphorus, magnesium, vitamin D and fluoride. Washington, DC: National Academy Press; 1997.
23. IOM. Dietary reference intakes for vitamin A, vitamin K, arsenic, boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, vanadium and zinc. Washington, DC: National Academy Press; 2002.
24. Metz CE. Basic principles of ROC analysis. Semin Nucl Med. 1978;8:283–98.[Medline]
25. Dewey KG, Cohen R, Arimond M, Ruel MT. Developing and validating simple indicators of complementary food intake and nutrient density for infants and young children in developing countries: final report. Washington, DC: The Food and Nutrition Technical Assistance Project and Academy for Educational Development; 2005.
26. Mukuria AG, Kothari MT, Abderrahim N. Infant and young child feeding update; 2006 [cited 2008 Feb 27]. Available from: http://www.fantaproject.org/downloads/pdfs/IYCF_Update_2006.pdf.
27. Rocquelin G, Tapsoba S, Kiffer J, Eymard-Duvernay S. Human milk fatty acids and growth of infants in Brazzaville (The Congo) and Ouagadougou (Burkina Faso). Public Health Nutr. 2003;6:241–8.[Medline]
28. Working Group on Infant and Young Child Feeding Indicators. Developing and validating simple indicators of dietary quality and energy intake of infants and young children in developing countries: summary of findings from analysis of 10 data sets. Washington, DC: The Food and Nutrition Technical Assistance Project and Academy for Educational Development; 2006.
29. WHO Multicentre Growth Reference Study Group. WHO Anthro 2005 software and macros; 2005 [cited 2008 Feb 27]. Available from: http://www.who.int/childgrowth/standards/en/.
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