Purpose: Growing concern about excess added sugar intake and associated adverse health effects has increased interest in non-nutritive sweeteners (NNS) as low-calorie alternatives that preserve sweetness. Previous studies focus on health effects of replacing added sugar, or environmental impacts of NNS alone. However, none evaluate the environmental impact ramifications of replacing added sugar with NNS in a whole dietary setting. This study addresses that gap.

Methods: The baseline diet reflected an average diet of Dutch adults consuming >2200 kcal/day (mean 2866 kcal/day). Added sugar (54 g/day), identified from recipe data, was replaced with steviol glycosides and a bulking agent (e.g., sorbitol) to create the NNS diet. Both diets were linked to life cycle assessment data and optimized separately for nutritional adequacy and the 2023 IPCC 1.5°C target of 2.04 kgCO₂-eq/day.

Results: Both diets had equivalent global warming potential (GWP, 4.18 kgCO₂-eq/day), but the NNS diet used 11% more water (compared to 1.19x10^-1 m³/day of baseline diet). When optimized for nutritional adequacy, GWP for both diets reduced 13%, and water consumption increased 3-9%. When optimized for nutrient adequacy and emissions targets, water consumption decreased by 11-15% across both diets.

Conclusion: These results highlight an opportunity for policymakers and consumers to focus on the health benefits of added sugar reduction rather than environmental trade-offs. Both dietary patterns can be further improved regarding nutritional and climate goals, suggesting that balanced, low-emission diets are attainable across different sweetness strategies. The study identifies methodological challenges in modeling realistic dietary substitutions and provides guidance for future research.