How to improve sustainability of nutrient dense diets for children and adolescents: an exemplary assessment in Germany.

Background: The global climate crisis requires a paradigm shift in dietary concepts, respecting the needs of children. A global reference diet has been suggested by the EAT-Lancet Commission. On this basis, the detailed "Planetary Health Diet Index" (PHDI) has been proposed. The objective of this assessment is (1) to apply the PHDI to the Food-Based Dietary Guidelines, the so-called Optimized Mixed Diet (OMD) for children and adolescents in Germany in its original composition and (2) to check how the planetary value of the OMD could be improved by modifying food selection within meals while keeping the high nutrient densities of the guideline diet.

Methods: The PHDI specifies 16 food groups and their proportion of total daily energy intake. The PHDI of the original OMD was calculated by assigning the foods of the 7-day menu to the PHDI food groups in order to score them. In this way, it became apparent which food groups had the potential to improve the sustainability. The diet was then updated by either reducing or increasing individual foods from these food groups in the meals and deriving the resulting PHDI. The nutrient densities of the original and updated daily OMD were calculated.

Results: The original diet obtained a PHDI score of 68.24 points, representing 45.5% of the theoretical maximum of 150 points. The following food groups achieved 9.9 to 10 out of 10 points: fruits, total vegetables, fish & seafood, vegetable oils, chicken (and substitutes). Conversely, food groups receiving a zero score included tubers & potatoes, dairy, red meat, animal fat, and added sugars. The updated diet resulted in increased consumption of 'nuts & peanuts', 'legumes', 'green vegetables', 'whole grains', and decreased consumption of 'tubers & potatoes' and 'red meat'. Overall, the PHDI increased from 68.24 to 81.51 points with the updated OMD, reflecting a 13.27% increase compared to the original diet. The nutrient densities were not significantly affected, but even slightly increased for most nutrients.

Conclusions: The PHDI was applied to demonstrate how the sustainability of the guideline diet for children and adolescents in Germany could be improved through changes in individual food groups that can be easily implemented in practice while maintaining high nutrient densities and acceptability for children.

Trial registration: NA.