Metrics for impact on diet quality in agricultural projects:

Strengths and limitations of indicators of dietary diversity

Mary ArimondIFPRI, June 6, 2013

Program in International and Community NutritionUniversity of California, Davis

Outline

• When is it appropriate to measure diet quality? - questions for project planners

• Measuring diet quality – why dietary diversity?

• How to operationalize & measure it

• Strengths & limitations of dietary diversity indicators; some misconceptions & pitfalls

Questions for project planners• Is improving overall diet quality an explicit project

objective? Do you expect diets to diversify, and if so why/how?

• Within diet quality, is the main concern intakes of micronutrients? Or other dimensions of diet quality (e.g. obesigenic diets)?

• Is the objective more narrow - increase intake of single/few targeted foods?

• Whose diet quality – entire household or target individual(s)?

Seed grants

Measuring diet quality – Why dietary diversity?

• Dietary diversity (DD) is one important dimension of diet quality (also balance, moderation, etc.)

• Consistently associated with micronutrient density of the diet (infants), and micronutrient adequacy (women), in multi-site studies

• Relatively simple to measure, & relevant across various cultural dietary patterns• Other multidimensional indices of diet quality can take much work to

adapt and validate across settings (e.g. U.S. Healthy Eating Index)

Why measure dietary diversity(2)?

• All food-based national dietary guidelines include this dimension

• Also included in WHO guidelines for feeding infants and young children, and operationalized in WHO indicator for global use

Dietary diversity and nutrient density(Working Group on IYC Feeding Indicators 2006)

Breastfed infants 6-8 mo, MMDA by # food groups yesterdayM

MD

A

“MMDA” is a measure of the adequacy of nutrient density, relative to needs, and averaged across 9 “problem nutrients”

IYCF DD indicator for 6-23 moPercent with 4 or more food groups – WHO, 2008

EthiopiaNigerBurkina FasoMali

DRCMozambiqueKenyaGhana

BangladeshIndiaCambodiaIndonesia

HaitiColombiaBoliviaPeru

Dietary diversity & micronutrient adequacy(Arimond et al., Women’s Dietary Diversity Project, J Nutr. 2010)

“MPA” is probability of adequacy averages across 11 micronutrients

Associations between DD & other outcomes• DD is associated with height-for-age (cross-sectional studies)

(Arimond & Ruel 2004; Sawadogo et al 2006; Moursi et al. 2009; Marriot et al 2012; Menon et al 2013)

• But few longitudinal studies; one failed to show association between DD and subsequent infant growth (length/height) (Bork et al, 2012)

• In one study, DD was associated with vitamin A status in women in Kenya, even after adjustment for vitamin A intake (Fujita et al 2012)

• In one study, DD was protective/ associated with CD4 counts, anemia, and mortality HIV+ adults (Rawat et al 2013)

• DD within fruit and vegetable groups has been associated with reductions in chronic disease risk (many studies)

Operationalizing dietary diversity –whose?

• Household-level indicators – validated against HH-level calorie (energy) availability and NOT as an indicator of diet quality, and not for specific vulnerable individuals

• Concept of mother as sentinel has been proposed, but intake of nutrient-dense food groups differs between mothers and infants (Nguyen et al. 2013)

Operationalizing individual dietary diversity

• DD has been defined & operationalized many ways– Number of individual foods vs. number of food groups

(with different levels of aggregation)– Varying recall periods (yesterday & last wk most common)– Minimum quantity limits– Free recall vs. list-based recall– Indicators can be dichotomous (“% with low diversity”) or

quasi-continuous scores

– Guidance available (next slide) but…

– Trade-offs between one-size fits all vs. project-specific indicators

WHO IYCF indicators for global use

FAO guidelines, HH & individual DD (adult)

Limitations of DD indicators• Measurement error and day-to-day variability in

diets mean the indicators are “noisy” at individual level

• Relatively simple, but survey instruments need to be adapted locally (food lists and strategy for excluding trivial amounts)

• Information on responsiveness is still limited as the indicators are new

• Up to now, no consensus on a dichotomous indicator for adult women (work in progress)

Limited information on responsiveness

• Up to now, few studies documenting responsiveness to interventions, shocks

• Study of 2008 food price shock in Burkina Faso showed impact on DD (next slide)

• Inclusion of indicators at baseline and post-intervention in Feed the Future projects will yield more insights in coming years (18 countries, large geographic areas)

Response to spike in food prices*Ouagadougou

2007 20084.9

5.1

5.3

5.5

5.7

5.9

Decrease in dietary diversity

Mean DDS (Ad-justed)

Nb of food groups

• P<0.0001

Food groups that showed the largest percent decrease were nutrient-dense: Dairy, meat, poultry, fruits, vitamin A-rich vegetables, nuts & seeds

*(Martin-Prevel et al, presented FENS Madrid 2011)

Misconceptions & pitfalls• DD indicators are not a proxy for nutritional status,

they are a proxy for diet quality

• Household-level indicators are not sufficient to assess diet quality of vulnerable groups (infants, women); some household-level indicators include non-nutritive foods/drinks

• Use for population/group-level description, never for screening/targeting individuals

• For repeat uses in same population, and for comparisons between populations, attend to seasonality

Dietary diversity indicators are…• …robust & useful population-level proxies of

micronutrient density/adequacy – an important dimension of diet quality

• ….associated with growth & health outcomes, but not a proxy for these

When choosing or designing indicators consider:

What makes sense based on intervention design

Comparability across sites, when this is relevant

Audiences for results, communication needs

Thank you!World Health Organization Indicators for Assessing Infant and

Young Child Feeding Practices: Part II Measurement

http://whqlibdoc.who.int/publications/2010/9789241599290_eng.pdf

Food and Agriculture Organization Guidelines for Measuring Household and Individual Dietary Diversity

http://www.fao.org/docrep/014/i1983e/i1983e00.pdf

marimond@ucdavis.edu