Different foods and food groups are good sources for various macro- and micronutrients, so a diverse diet best ensures nutrient adequacy. The principle of dietary diversity is embedded in evidence-based healthy diet patterns, such as the Mediterranean diet and the “DASH” diet (Dietary Approaches to Stop Hypertension), and is affirmed in all national food-based dietary guidelines. The World Health Organization (WHO) notes that a healthy diet contains fruits, vegetables, legumes, nuts and whole grains.

A diverse diet is most likely to meet both known and as yet unknown needs for human health. In addition to our knowledge of protein, essential fatty acid, vitamin and mineral requirements, new knowledge about health effects of a wider range of bioactive compounds continues to grow. Considering plant foods alone, it is currently estimated that there are approximately 100,000 bioactive phytochemicals and that “observed health effects associated with vegetable, fruit, berry, and whole grain consumption can likely be explained by the combined action of many different phytochemicals and other nutrients” (Nordic Nutrition Recommendations 2012. Copenhagen: Nordic Council of Ministers).

Dietary diversity is one dimension of diet quality. Diverse diets can still lack macronutrient balance and/or moderation, which are other dimensions of diet quality. Diets lack balance when they are too high or too low in fat, protein or carbohydrate. Diets lack moderation when they include excessive consumption of energy (calories), salt or free sugars. Food group diversity does not ensure balance or moderation. Food group diversity also does not in itself ensure that the carbohydrates, proteins and fats consumed are of high quality. Dietary diversity is, however, associated with better micronutrient density (micronutrients per 100 calories) and micronutrient adequacy of diets.

Compared with men, women – and particularly women of reproductive age - require diets that are higher in nutrient density (nutrients per 100 calories). This makes them vulnerable to micronutrient deficiencies. Micronutrient deficiencies impair women’s health and the health of their children. In some settings, women may be disadvantaged in intra-household distribution of nutrient-dense foods (for example, animal-source foods). Improved dietary diversity is one of several strategies for improving micronutrient intakes for women of reproductive age.

MDD-W is the acronym for “Minimum Dietary Diversity-Women.” MDD-W is a dichotomous indicator of whether or not women 15-49 years of age have consumed at least five out of ten defined food groups the previous day or night. The proportion of women 15–49 years of age who reach this minimum in a population reflects one important dimension of diet quality.

Even though the indicator is measured by asking questions of individual women, it is a population-level indicator, i.e. it is designed to tell us something about micronutrient adequacy of groups of women.

Groups of women who achieve minimum dietary diversity (i.e. meet the threshold of five or more groups) are more likely to have higher (more adequate) micronutrient intakes than groups of women who do not.

The 10 food groups that comprise the MDD-W indicator are:

1. Grains, white roots and tubers, and plantains
2. Pulses (beans, peas and lentils)
3. Nuts and seeds
4. Dairy
5. Meat, poultry and fish
6. Eggs
7. Dark green leafy vegetables
8. Other vitamin A-rich fruits and vegetables
9. Other vegetables
10. Other fruits

Because the indicator is calculated based on a single day, and because it is calculated without information on quantities consumed, the indicator does not provide information about diet quality for individual women.

Even for groups of women, meeting the threshold of five or more food groups does not guarantee that micronutrient needs are met, though it increases the likelihood that they are being met. Whether or not intakes are adequate depends on quantities of nutrient-dense foods consumed, as well as on dietary diversity.

For the same reasons noted above (normal day-to-day variability and lack of information on quantity), Minimum Dietary Diversity for Women of Reproductive Age (MDD-W) is not the best indicator for many research settings and questions. Quantitative recalls, repeated recalls and locally validated food frequency questionnaires would all provide stronger measures for use in research using a variety of analytic approaches. The MDD-W indicator was not designed as a research tool.

It is appropriate to measure Minimum Dietary Diversity for Women of Reproductive Age (MDD-W) when a simple proxy indicator is needed to describe one important dimension of women’s diet quality – micronutrient adequacy – in national and subnational assessments.

It is appropriate use MDD-W to compare with previous assessments so long as survey timing accounts for seasonality, as seasonal differences can affect the relationship between food group diversity and micronutrient adequacy.

The indicator may be useful in advocacy and policy settings, when a dichotomous (yes/no) indicator is often needed.

It is not appropriate to measure and use Minimum Dietary Diversity for Women of Reproductive Age when an indicator is needed for screening and/or targeting individual women.

The indicator also should not be used in isolation to make targeting decisions for groups/ populations, although it may provide useful descriptive information to contribute to such decisions when used as part of a broader suite of indicators.

Yes, a 1-day recall is sufficient to capture diversity for groups of women. For any individual, it is normal for the diet to vary from day to day, so one day diversity may be very low, while it is very high the next day. However, when assessing dietary diversity for groups of women, these high and low diversity days for individuals balance each other, and the summary at the group level is accurate.

Quantitative dietary recalls involve asking the respondent to estimate the amount of each food and ingredient consumed over a defined time period. A variety of two- and three-dimensional food models and/or actual foods may be used to help the respondent estimate. Especially in populations with low literacy and numeracy, quantitative recalls are challenging and require highly trained and skilled enumerators. Detailed information on local recipes for mixed dishes and on nutrient content of foods is required for data processing, analysis and interpretation.

Qualitative recalls involve asking respondents to recall food items consumed over a defined time period, but respondents are not asked to recall the amounts consumed. This type of recall is much simpler to implement and to analyse.

Minimum Dietary Diversity for Women of Reproductive Age can be measured with a qualitative recall. A quantitative recall is not required.

In situations where a quantitative recall is feasible, many more detailed indicators of diet quality can be generated.

The biggest challenges in measuring food group diversity relate to the handling of mixed dishes and the classification of ingredients, particularly those that might be consumed in trivial quantities in any one serving of a mixed dish. Foods prepared outside the home (i.e. not by the respondent) also present challenges. There are two levels of challenges: first in adapting the model questionnaires to new contexts and second in training enumerators to properly record mixed dishes and foods prepared outside the home.

Besides these specific challenges, the overall process of creating a high-quality questionnaire for the first time in a new country or geographic area is a challenge because of the need for appropriate cultural and linguistic adaptation, and well as customisation via local examples of the foods classified into each food group.

Approaches to meeting these challenges are discussed in detail in Sections 2–5 of Minimum Dietary Diversity for Women – A guide to measurement, and in Appendix 2 of the guide, which provides a comprehensive list of example foods for each group.

The ten food groups “counted” in the Minimum Dietary Diversity for Women of Reproductive Age indicator are:

1. Grains, white roots and tubers, and plantains
2. Pulses (beans, peas and lentils)
3. Nuts and seeds
4. Dairy
5. Meat, poultry and fish
6. Eggs
7. Dark green leafy vegetables
8. Other vitamin A-rich fruits and vegetables
9. Other vegetables
10. Other fruits

Many foods are easily classified into the correct group, but other foods present classification challenges. In general, classifications follow culinary and not botanical definitions (e.g. tomatoes are classified with vegetables and not with fruits). Minimum Dietary Diversity for Women – A guide to measurement provides detailed descriptions for each of the ten groups in Section 2. Appendix 2 provides lists of items that can be classified into each group. Appendix 2 also provides a table explaining the rationale for several challenging classifications.

This process has several steps, and ideally will involve consultation with a nutritionist with expert knowledge of local foods. In some settings, previous survey tools may be excellent resources, provided they were well adapted. Adaptation involves the following steps, which are described in detail in Section 4 of Minimum Dietary Diversity for Women – A guide to measurement:

• Decide whether to use the open recall or list-based method for querying respondents about foods consumed.
• Decide whether or not to include optional categories of foods, which are not “counted” in the Minimum Dietary Diversity for Women of Reproductive Age (MDD-W) indicator, such as sugar-sweetened beverages, sweets, fats and oils, and savoury and fried snacks.
• Make an initial translation of the MDD-W model questionnaire into (one of) the main survey language(s); model questionnaires are provided for both list-based and open recall methods in Appendix 3 and Section 3 of Minimum Dietary Diversity for Women – A guide to measurement, respectively.
• Refine the questionnaire through linguistic and cultural adaptation. This process can involve the nutritionist, the survey designers, trainee enumerators and – where resources permit – additional key informant interviews or focus groups to generate complete examples for the foods listed in each group.
• Translate into additional languages as needed.

The adaptation process should be followed by field/pilot testing and further refinement, as indicated in Section 4 of Minimum Dietary Diversity for Women – A guide to measurement.

The Minimum Dietary Diversity for Women of Reproductive Age (MDD-W) indicator includes ten food groups:

1. Grains, white roots and tubers, and plantains
2. Pulses (beans, peas and lentils)
3. Nuts and seeds
4. Dairy
5. Meat, poultry and fish
6. Eggs
7. Dark green leafy vegetables
8. Other vitamin A-rich fruits and vegetables
9. Other vegetables
10. Other fruits

However, to make the questionnaire more intuitive for enumerators, three of the MDD-W food groups are divided into subgroups. “Grains, white roots and tubers, and plantains” provide one point when calculating the score, but there are two subgroups (i.e. rows) on the questionnaire, one for grains and foods made with grain and one for white roots, tubers and plantains. Meat, poultry and fish provide one “point” when calculating the indicator, but there are three subgroups (i.e. rows) on the questionnaire (one each for meat, poultry and fish/seafood). The “Other vitamin-A rich fruits and vegetables” group is divided into two subgroups (i.e. rows): one for vitamin A-rich fruits and one for vitamin A-rich vegetables, other than dark green leafy vegetables.

In addition to these subgroups, which result in 14 rows on the questionnaire, there are 6 optional categories and 2 required categories on the questionnaire. None of these count in the calculation of MDD-W.

The optional categories are:

• Insects and other small protein foods
• Red palm oil
• Other oils and fats
• Savoury and fried snacks
• Sweets
• Sugar-sweetened beverages

The required categories are:

• Condiments and seasonings
• Other beverages and foods

See Section 2 of Minimum Dietary Diversity for Women – A guide to measurement for a full explanation of all MDD-W food groups and of other optional and required categories for the questionnaire.

The answer to this question depends on whether you are planning to use the open recall method or the list-based method.

In the open recall method, the enumerator does not read a list of foods or groups to the respondent. Therefore, the number of rows on the questionnaire will not affect responses. However, it is very important not to “collapse” categories in such a way that it is not possible to capture information on the ten distinct Minimum Dietary Diversity for Women of Reproductive Age (MDD W) food groups.

On the model questionnaire, in addition to rows capturing information on the MDD-W food groups, there are six optional and two required categories. It is okay to change the number of rows by dropping the optional categories (e.g. “Sweets”, “Sugar-sweetened beverages”, “Other fats and oils”), but the questionnaire must include the final two rows: a row for foods/ingredients usually used in very small quantities (“Condiments and seasonings” category) and a row for all “other” foods and beverages. Section 2 of Minimum Dietary Diversity for Women – A guide to measurement provides a detailed description of and rationale for each food group and of the other optional and required categories.

In the list-based method, the enumerator does read a list of example foods, in groups. Responses, and the resulting “count” of food groups, are influenced by the total number of categories and by the choices made in disaggregating categories. In general, the larger the number of questions on a list-based questionnaire, the larger the number of “yes” responses, which in some cases leads to a higher count among the ten MDD-W food groups. If users wish to compare across time or space, it is particularly important that the list-based questionnaires remain the same/have the same number of questions.

For both the open recall and list-based questionnaires, it is allowable to add questions to capture information about specific, targeted food items. For the open recall, this will not bias responses. For the list-based questionnaires, additions should be few and made thoughtfully, to avoid biases in responses and in the constructed indicator.

Many different dietary diversity indicators have been used, particularly in research contexts. Some count individual food items, and others (like Minimum Dietary Diversity for Women of Reproductive Age [MDD-W]) are based on counts of food groups. A wide range of different indicators (counts and scores) have been found to relate positively to nutrient intake and other outcomes.1 Table 1 in Section 1 of Minimum Dietary Diversity for Women – A guide to measurement provides a comparison of several indicators.

The MDD-W differs from other food group diversity indicators in two ways.

First, the MDD-W was developed based on analysis of nine data sets from Africa and Asia using a common analytic protocol and relating the indicator to the micronutrient adequacy of women’s diets across 11 micronutrients. Another indicator, the infant and young child feeding indicator of minimum dietary diversity, was also based on analysis of multiple data sets using a common protocol.2 However, many other dietary diversity indicators in use have not been assessed in multiple settings.

Second, responding to demand for a dichotomous (yes/no) indicator, MDD-W provides a threshold value of five or more of ten food groups to use as a criterion in assessments. This allows expression of the prevalence of meeting “Minimum dietary diversity for women of reproductive age” at the population level.

1 Ruel, M.T. Operationalizing dietary diversity: a review of measurement issues and research priorities. 2003. J Nutr., 133(11 Suppl 2): 3911S–3926S.

2 WHO. 2008. Indicators for assessing infant and young child feeding practices. Part I : Definitions. Geneva, WHO.

Different dietary diversity indicators have been developed to reflect household food security, infant and young child feeding practices and micronutrient adequacy for women of reproductive age, among other topics. Table 1 in Section 1 of Minimum Dietary Diversity for Women – A guide to measurement provides a comparison of several indicators.

Selection of an indicator depends on its intended use and the intended audience for results. Different indicator qualities are required and prioritised depending on whether the indicator is needed for assessment, accountability, advocacy, screening, targeting and/or evaluation. No single indicator will be best for all of these purposes.

The Minimum Dietary Diversity for Women of Reproductive Age indicator was developed for use in assessment when a simple proxy indicator is needed, and when it is preferable, for communication and advocacy purposes, to be able to express results as a proportion of a population meeting a criterion/threshold value.

The Minimum Dietary Diversity for Women of Reproductive Age (MDD-W) indicator should not been viewed as a message or used as guidance for developing messages. This is a common mistake.

Indicators, dietary guidelines and behaviour change messages are developed through very different processes. In particular, because it was developed for global use, MDD-W may or may not align perfectly with best messages for improving diets in any given content.

Development of national dietary guidelines is a scientific and political process, incorporating a range of evidence and stakeholder perspectives. The types of evidence used to inform guidelines include assessments of food and nutrient intakes, food supplies, prevalence and public health importance of diet-related health and nutrition outcomes, and cultural preferences, among others.

Similar to dietary guidelines, programmatic efforts involving social and behaviour change communication are grounded in deep knowledge of context and in examinations of how best to motivate behaviour change given the cultural context and the potential motivators for and constraints to change.

Food group diversity indicators developed for global use, such as the MDD-W, of necessity lack the cultural and contextual specificity described above for dietary guidelines or other communications efforts. Also, MDD-W provides for a minimum standard – diversification – but is “silent” on quantities consumed and around other dimensions of diet quality (balance, moderation). Conveying messages about diversity alone is necessary but not sufficient to improve diets.

In a qualitative open recall, the enumerator asks a series of standard probing questions to help the respondent recall all foods and drinks consumed the previous day and night, and also probes for main ingredients in mixed dishes. The recall is “open” because the enumerator does not read predefined foods/groups to the respondent.

When a list-based questionnaire is used, the enumerator does read a list of foods to the respondent. The enumerator informs respondents that they should respond “yes” for each food consumed during the specified recall period of the previous day and night. The enumerator continues by reading a list of foods organized in groups, giving multiple examples for each food group.

Both methods are described in Section 1 of Minimum Dietary Diversity for Women – A guide to measurement, and Table 2 lists advantages and disadvantages of each method. Based on an evaluation of the advantages and disadvantages, the open recall is recommended, whenever feasible.

Mixed dishes and street foods are among the biggest challenges encountered in the measurement of food group diversity in diets. Section 2 of Minimum Dietary Diversity for Women – A guide to measurement provides a discussion of these issues and guidance for classifying foods and ingredients into groups. Sections 3 and 4 provide guidance on handling this issue during questionnaire adaptation and enumerator training, respectively.

Fortified foods are less challenging because, for the purposes of measuring food group diversity, they can be categorised in their “home” food group (for example, fortified wheat flour can be categorised with grains, fortified oil with fats and oils). Users interested in capturing coverage with fortified or biofortified foods or products are advised to address this with separate questions or a separate survey module.

Although fortified products can contribute to micronutrient adequacy, such foods are usually fortified with either a single micronutrient or a small number of micronutrients. Their use does not undermine the value of and need for diverse diets, which provide a far wider range of nutrients and bioactive compounds.