Diet composition and staple-food dependence as structural determinants of global dietary diversity and nutrition security

Dietary diversity is a key indicator of nutritional adequacy and a crucial component of sustainable food systems. However, the relative contributions of plant- and animal-derived products to national and global dietary patterns remain understudied. Using the Food Balance Sheet datasets from FAOSTAT and the Simpson diversity index, this study investigates how the caloric share of plant- and animal-sourced foods shapes diet diversity across different nations. The results revealed the coexistence of a high share of plant-based diets (~ 90%) and high diet diversity (~ 0.90), particularly in low-income countries. However, a high plant share is characterized by the dominance of staple foods contributing more than 70%, mainly cereals such as maize, rice, and wheat, while having a vast and limited share of nutrient-dense food products, including animal-sourced foods, legumes and fruits. Similarly, high-income countries exhibit high diet diversity (~ 0.90 to ~ 0.95), albeit with a more balanced contribution from plants and animals. The food supply profile of these nations is characterized by animal-sourced foods contributing ~ 30%, whereas cereals, fruits, vegetables and sweeteners each contribute less than 20%. These findings highlight that single dietary diversity metrics alone cannot capture nutritional adequacy. Nutrition security requires rebalancing caloric shares across food groups, particularly by moderating staple dominance and ensuring adequate inclusion of nutrient-rich plant and animal foods. This study emphasizes the need to move beyond “absolute diversity” indices toward structural measures that integrate food composition and balance, thereby providing a more accurate “qualitative diversity” lens for guiding sustainable and nutrition-sensitive food policies.