Introduction

Food security is widely recognized as a fundamental component of social welfare and sustainable development. Ensuring that all individuals have continuous access to sufficient, safe, and nutritious food is essential for improving public health, enhancing labor productivity, and promoting long-term economic growth. In recent years, rising food prices, inflation, economic instability, and declining household purchasing power have raised increasing concerns about food security in Iran. These developments have highlighted the importance of monitoring not only the quantity of food consumed but also the quality of household diets. Daily per capita calorie intake is widely used as an indicator of the access dimension of food security, since it captures households' capacity to secure adequate dietary energy. Nevertheless, calorie intake alone cannot fully represent nutritional adequacy. Dietary diversity, which reflects the distribution of food consumption across different food groups, provides complementary information on diet quality and nutritional balance. Therefore, evaluating both calorie intake and dietary diversity provides a more comprehensive assessment of food security. The present study investigates food security based on calorie intake and dietary diversity among urban and rural households in Iran during 2011-2024.

Materials and Methods

This study used data from the Household Income and Expenditure Survey conducted annually by the Statistical Center of Iran during 2011-2024. Food security was evaluated in terms of access to dietary energy, using daily per capita calorie intake. Dietary diversity was measured using the Shannon Diversity Index, while dietary concentration was assessed using the Herfindahl–Hirschman Index (HHI). The analysis was conducted separately for urban households, rural households, and the national average to identify temporal trends and regional differences in food consumption patterns. The statistical significance was examined using the modified Mann-Kendall test and t-test, respectively.

Results and Discussion

The findings reveal a continuous deterioration in food security throughout the study period. Average daily per capita calorie intake was estimated at 2417 kcal nationwide, 2338 kcal in urban areas, and 2634 kcal in rural areas. Although rural households consistently consumed more calories than urban households, both regions experienced substantial declines over time. At the national level, average calorie intake decreased from 2818 kcal in 2011 to 2042 kcal in 2024. Moreover, after 2019, average calorie intake fell below the reference threshold of 2300 kcal per person per day, indicating a gradual significant decline in households' access to sufficient dietary energy. These findings suggest a weakening of food security during recent years. Changes in dietary diversity followed a similar pattern. The Shannon Diversity Index declined significantly after 2018, whereas the Herfindahl–Hirschman Index increased significantly over the same period, indicating that household diets became less diverse and more concentrated on a smaller number of food groups. Consequently, calorie intake was increasingly derived from a limited set of dietary sources. Analysis of food-group contributions further demonstrated that cereals remained the primary source of dietary energy throughout the study period, providing more than half of total calorie intake. In contrast, nutrient-rich food groups-including meat, dairy products, legumes, fruits, and vegetables—accounted for relatively small shares of total energy intake. This pattern indicates that although households continued to satisfy a considerable proportion of their energy requirements through cereals, their diets became less balanced from a nutritional perspective. The simultaneous decline in calorie intake and dietary diversity suggests that households have faced increasing difficulties in maintaining both sufficient and nutritionally balanced diets. Although this study does not directly investigate the determinants of these trends, the observed changes are consistent with the effects of declining purchasing power, rising food prices, and increasing household budget constraints in recent years. Therefore, the deterioration in food security appears to involve both reduced dietary energy and declining dietary quality. The results also demonstrate the value of combining calorie-based indicators with dietary diversity measures. While calorie intake reflects the quantitative dimension of food security, dietary diversity captures qualitative aspects of food consumption that cannot be identified through calorie assessment alone. Considering these indicators simultaneously provides a more comprehensive understanding of changes in household food security over time.

Conclusion

The findings indicate that food security in Iran weakened in both quantitative and qualitative dimensions during 2011-2024. Daily calorie intake declined steadily and significantly, while dietary diversity decreased and dietary concentration increased significantly. These changes suggest that households not only consumed less dietary energy but also relied on a narrower range of food groups (mostly cereals), reducing the overall quality of their diets. The results underscore the importance of incorporating dietary diversity indicators alongside calorie-based measures when evaluating food security. These findings indicate that food support policies should be redesigned to incorporate dietary diversity and quality, alongside minimum energy adequacy, as core dimensions of food security assessment.