Julie Marie Lengle

• Lengle, Julie Marie; Zhang, Chi; Frigessi, Arnoldo & Andersen, Lene Frost (2025). Nutritionally adequate, healthy, and climate-friendly diets following the Nordic Nutrition Recommendations 2023: an optimization study for Norway. Frontiers in Nutrition. 12, p. 1–16. doi: 10.3389/fnut.2025.1485287. Full text in Research Archive Show summary

  Background: Reducing red meat consumption is an effective tactic for decreasing environmental impact of diets while maintaining nutritional adequacy, healthiness, and overall consumer acceptability. Still, dietary change in favor of plant foods is a controversial climate mitigation measure, especially in the Nordic region where agri-food heritage is linked to ruminant husbandry. Objective: In this study we aimed to explore sustainable diets for the Norwegian context by (1) investigating the environmental impacts of nutritionally optimized diets following the Nordic Nutrition Recommendations 2023 (NNR2023), (2) estimating potential for environmental impact reduction across scenarios of meat and legume consumption, and (3) identifying nutritional challenges. Methods: Quadratic optimization was employed to minimize departure from the average observed Norwegian diet while meeting nutrient, health, and carbon footprint constraints. The diet of Norwegian adults was estimated based on results from the national dietary survey Norkost 3. Global warming potential (GWP), freshwater and marine eutrophication, terrestrial acidification, water use, and transformation and use of land were calculated using data from the Norwegian Life Cycle Assessment Food Database version 01. Diets were optimized to meet NNR2023 nutrition and health recommendations for nutrients and food groups. Optimizations were first run without constraints on GWP, for three diet scenarios: (1) nutrients and health-based targets for food amounts ( NNR2023 ), (2) nutrients and health-based targets for food amounts with ruminant meat ≥ observed intake (62 g/day) ( Ruminant ), and (3) nutrients and health-based targets for food amounts with legumes content ≥40 g/day (Legumes). Then, GWP constraints were applied in 5% increments until no solution was found. The optimal diet for each scenario was defined as the diet with the largest feasible reduction in GWP (NNR2023+/Ruminant+/Legumes+). Results: Optimizing the diet to meet nutrient and health constraints alone resulted in a modest decrease in GWP (NNR2023); retaining ruminant meat consumption (Ruminant) impeded the reduction (−9% vs. 0%). Diets following NNR2023 nutrient and health constraints alone were feasible up until a 30% reduction in GWP (NNR2023+). A 35% reduction in GWP was achieved when legumes were added to the diet (Legumes+), while diets retaining 62 g of ruminant meat were not identified beyond a 15% reduction in GWP (Ruminant+). Sodium and selenium were the strongest limiting constraints in all scenarios. Diets with a 40% reduction in GWP were identified when nutrient constraints were lowered from the Recommended Intake to the Average Requirement (NNR2023+/Legumes+). Reductions in GWP coincided with reductions in all measured environmental indicators except marine eutrophication. Conclusion: The NNR2023 guidelines outline diets that have generally lower environmental impacts than the average Norwegian diet, though outcomes depend on distribution of meat and legume consumption in the diet. Regardless of degree of environmental impact reduction, diets following NNR2023 guidelines will require significant dietary changes compared to observed intake, including an increase in consumption of fruits, vegetables, and grains, and a strong decrease in consumption of red meat, total meat, and discretionary foods. Preventing the model from removing any ruminant meat from the diet limited GWP reduction to 15% and induced considerable changes in intake of other food groups, especially a decrease in other types of meat.

• Lengle, Julie Marie; Bjøntegaard, Marie Michaelsen; Carlsen, Monica Hauger; Jafarzadeh, Sepideh & Andersen, Lene Frost (2024). Environmental impact of Norwegian self-selected diets: comparing current intake with national dietary guidelines and EAT-Lancet targets. Public Health Nutrition (PHN). ISSN 1368-9800. 27(1). doi: 10.1017/S1368980024000715. Full text in Research Archive Show summary

  Objectives: Dietary environmental impact in a Norwegian adult population was estimated for six environmental impact categories. Moreover, environmental benefits of scenario diets complying with the Norwegian Food-Based Dietary Guidelines (FBDG) and the EAT-Lancet reference diet were assessed. Design: The current diet of Norwegian adults was estimated according to 24-h dietary recall data from a national dietary surveillance survey (Norkost 3). Scenario diets were modelled to represent the Norwegian FBDG and the EAT-Lancet healthy reference diet. Dietary environmental impact in terms of global warming potential, freshwater and marine eutrophication, terrestrial acidification, water use and transformation and use of land was estimated for the current and scenario diets using environmental impact data representative of the Norwegian market. Significant associations between impact and gender/educational attainment were assessed at P < 0·05. Setting: Norway. Participants: Adults (n=1787) aged 18–70 years who participated in the Norkost 3 survey (2010–2011). Results: Environmental impact varied significantly by gender and educational attainment. The food groups contributing most to environmental impact of Norwegian diets were meat, dairy, beverages, grains and composite dishes. Compared with the current Norwegian diet, the FBDG scenario reduced impacts from 2 % (freshwater eutrophication) to 32 % (water use), while the EAT-Lancet scenario reduced impacts from 7 % (marine eutrophication) to 61 % (land use). The EAT-Lancet scenario resulted in 3–48 % larger reductions in impact than the FBDG scenario. Conclusions: The Norwegian FBDG, while not as environmentally friendly as the EAT-Lancet reference diet, can still be an important tool in lessening environmental burden of Norwegian diets.

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• Lengle, Julie Marie (2024). Norsk kosthold optimalisert i henhold til Nordic Nutrition Recommendations 2023 og miljømessig bærekraft. Full text in Research Archive
• Lengle, Julie Marie (2024). Optimizing Norwegian diets to meet the Nordic Nutrition Recommendations 2023 and reduce environmental impacts. Full text in Research Archive
• Lengle, Julie Marie (2023). Environmental impact of Norwegian self-selected diets:  Comparing current intake with national dietary guidelines and EAT-Lancet targets. Full text in Research Archive
• Lengle, Julie Marie & Andersen, Lene Frost (2026). Healthy and environmentally sustainable diets for Norway: current patterns and future scenarios. The NOR-Eden Project. Universitetet i Oslo. ISSN 9788234809033. Full text in Research Archive Show summary

  Current food systems fail to deliver good health and are major drivers of environmental change. The aim of this thesis was to address key questions about the health and environmental implications of implementing the Nordic Nutrition Recommendations 2023 (NNR2023) and other dietary frameworks, including the Norwegian Food-Based Dietary Guidelines (FBDGs, 2012) and the EAT-Lancet Planetary Health Diet (PHD), under Norwegian conditions. The work uses detailed intake data from the national Norkost 3 (2010–2011) and Norkost 4 (2022–2023) dietary surveys of adults and older adults, linked to life cycle assessment data for six environmental indicators (e.g. greenhouse gas emissions, land use, eutrophication). We quantified the environmental impact of Norwegian adult diets across six indicators, assessed adequacy of utilizable protein in diets with higher plant protein shares, and applied constrained optimization to model culturally relevant diets that meet NNR2023 while reducing environmental pressures. Current Norwegian diets have high environmental footprints, largely driven by ruminant meat and dairy. Total protein intake is almost twice estimated requirements, and two thirds of protein comes from animal sources. Our analyses show that protein intake can be reduced and partially shifted from animal to plant sources without compromising adequacy for most adults, though some older women remain more vulnerable. FBDG aligned diets reduce environmental impacts, but more plant forward patterns and optimized NNR2023 consistent diets achieve considerably larger reductions, at the cost of marked changes in food choice. The findings highlight national FBDGs as a central tool to meet public health and environmental goals. However, the thesis work also underscores that achieving material dietary changes will require strong policy action and structural changes in food culture, particularly around ruminant meat, high fat dairy and the very low intake of legumes and other plant proteins.

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