Dietary diversity matters

There are many ways to conserve the planet’s precious biodiversity - the main one is diversifying our diet. Dietary diversity has long been recognized by nutritionists as a key element of high-quality diets. Many studies validated dietary diversity against nutrient adequacy. The micronutrient density of the diet is considered high when the dietary diversity is greater.

The Minimum Dietary Diversity for Women indicator

The MDD-W indicator was developed by FAO and partners to fill the need for a simple, food-based indicator for measuring dietary diversity and micronutrient adequacy, key dimensions of diet quality of women of reproductive age. This population–level qualitative indicator measures the proportion of women 15-49 years of age who consumed food items (at least 15g) from at least five out of the ten defined food groups the previous day or night. It is associated with a higher probability of nutrient adequacy for 11 micronutrients.

Why is dietary diversity important?

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).

What is the difference between dietary diversity and diet quality?

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.

Why focus on dietary diversity for women?

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.

What does the MDD-W indicator mean?

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 the 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

What does the Minimum Dietary Diversity for Women of Reproductive Age indicator NOT mean?

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.

When is it appropriate to measure and use Minimum Dietary Diversity for Women of Reproductive Age?

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.

When is it NOT appropriate to measure and use Minimum Dietary Diversity for Women of Reproductive Age?

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.