The Dietary Diversity Score (DDS) is a simple and valuable tool used in nutrition to assess the qualitative aspect of diet, particularly in resource-constrained settings. It is calculated by summing the number of unique food groups consumed by an individual or household over a specific recall period, typically 24 hours. A higher DDS is generally correlated with greater nutritional adequacy and overall diet quality.
The DDS Calculation Process: A Step-by-Step Guide
Calculating the DDS is a methodical process that requires careful data collection and classification. The most common approach uses a 24-hour dietary recall administered via a questionnaire.
Step 1: Conduct a 24-Hour Dietary Recall
- Select a Representative Period: Avoid days of unusual eating patterns, such as festivals or celebrations, as they can skew the results. The recall period is usually the day preceding the interview.
- Interview the Respondent: For individuals, this means interviewing the person themselves. For households, the person primarily responsible for food preparation is usually the respondent.
- Record All Meals and Snacks: Ask the respondent to list every food and drink item consumed during the entire 24-hour period, including meals and snacks. It is crucial to probe for forgotten items, such as fruits or beverages, that may not be initially recalled.
Step 2: Classify Foods into Standard Food Groups
After collecting the raw food data, each item must be categorized into a predefined list of food groups. Different indicators, such as the Household Dietary Diversity Score (HDDS) or Minimum Dietary Diversity for Women (MDD-W), use different food group classifications. The MDD-W, for example, is based on 10 specific food groups.
- Group items together: Combine all foods belonging to the same category. For example, a meal with rice and a snack with bread both fall under the 'grains' group.
- Handle mixed dishes: For complex meals like a stew, the enumerator must break down the dish into its individual food group components. For instance, a stew might contain meat, potatoes (roots/tubers), and various vegetables.
- Consider quantity thresholds: Some dietary diversity indicators, particularly those used for individual assessment like the MDD-W, recommend excluding trivial quantities of food used as condiments (e.g., less than 15g) to avoid skewing the score.
Step 3: Tally the Final Score
Once all consumed food items have been categorized, the DDS is a simple count. One point is awarded for each unique food group consumed at least once during the reference period, regardless of the quantity (above any relevant threshold). The final score is the total number of food groups tallied.
Example: Calculating the Minimum Dietary Diversity for Women (MDD-W)
As a concrete example, let's look at the MDD-W, which is used for non-pregnant women aged 15-49 years. The 10 food groups for this indicator are:
- Grains, white roots and tubers, and plantains
- Pulses (beans, peas, and lentils)
- Nuts and seeds
- Dairy
- Meat, poultry, and fish (flesh foods)
- Eggs
- Dark green, leafy vegetables
- Vitamin A-rich fruits and vegetables
- Other vegetables
- Other fruits
To calculate the MDD-W for an individual woman, you simply count how many of these ten groups she consumed over the past 24 hours. A woman who ate a dish with rice, chicken, and green vegetables would score at least 3 points, provided the quantities met the minimum threshold. The MDD-W is considered adequate if the score is 5 or higher.
Comparison of Different Dietary Diversity Scores
While the core calculation is a count of food groups, variations exist depending on the target group and purpose. The table below outlines key differences between the HDDS and MDD-W.
| Feature | Household Dietary Diversity Score (HDDS) | Minimum Dietary Diversity for Women (MDD-W) |
|---|---|---|
| Unit of Measurement | Household | Individual (women 15-49) |
| Food Groups | Typically 12 groups | 10 specific groups |
| Recall Period | 24 hours | 24 hours |
| Purpose | Proxy for household food access and socioeconomic status | Proxy for micronutrient adequacy in women |
| Scoring | Continuous score (0-12) | Dichotomous indicator (≥5 = adequate) |
| Limitations | Does not account for intra-household food distribution; no universal cut-off | Only a rough proxy for nutrient adequacy; requires quantity threshold |
Interpreting and Applying Your Dietary Diversity Score
A DDS is not a measure of calorie intake but rather of dietary quality and access to a variety of micronutrients. A high DDS suggests a varied diet, which is generally better for overall health, especially in vulnerable populations prone to micronutrient deficiencies. Conversely, a low DDS may indicate a monotonous, starchy-staple-based diet, potentially putting individuals at risk of nutrient deficiencies. It is a population-level indicator and not an absolute diagnostic tool for individuals. To get a more precise measure of nutrient adequacy, detailed 24-hour dietary recalls or weighed food records are necessary. For public health programs, DDS is an easy-to-use tool for monitoring and evaluating the impact of interventions.
Conclusion: The Value of Calculating Dietary Diversity
Calculating the dietary diversity score is a straightforward yet powerful method for assessing the quality of a diet. By following a standard procedure involving a 24-hour recall and classifying foods into established groups, one can derive a score that reflects the variety of foods consumed. Whether used at the individual level (like MDD-W) or household level (like HDDS), the DDS provides critical insights into nutritional status and food security. It is an efficient and practical indicator for public health professionals and researchers to monitor and promote healthier eating patterns globally. For more detailed guidelines, consult the FAO resources on measuring dietary diversity.
