Abstract Purpose There are increasing concerns regarding detrimental health effects of added sugar in food and drink products. Non-nutritive sweeteners (NNS) and sweetness enhancers (SE) are seen as viable alternatives. Much work has been done on health and safety of NNS&SE when consumed in place of sugar, but very little on their sustainability. This work aims to bridge that gap with an environmental study of replacing added sugar with NNS&SE in the context of drink and yoghurt. Methods A life cycle assessment (LCA) approach was used to compare environmental impact of a drink and yoghurt, sweetened with sucrose, to those sweetened with NNSs or an SE: stevia rebaudioside A, sucralose, aspartame, neotame, and thaumatin. Primary ingredients data were taken from preparation of foodstuffs for clinical trials. Results are reported via the ReCiPe 2016 (H) method, with focus on land use, global warming potential (GWP), marine eutrophication, mineral resource scarcity, and water consumption. Impacts are reported in terms of 1 kg product. Scenarios explore sensitivity of the LCA results to change in background processes, functional unit, and sweetener type. This research was conducted as part of the EU Horizon 2020 project SWEET (sweeteners and sweetness enhancers: impact on health, obesity, safety, and sustainability). Results and discussion Replacing sugar with an NNS or part-replacing with an SE is shown to reduce environmental impact across most impact categories, for example, on a mass basis, GWP for a drink reduces from 0.61 to approx. 0.51 kgCO2-eq/kg and for a yoghurt from 4.15 to approx. 3.73 kgCO2-eq/kg. Variability in environmental impact is shown to be relatively small between the NNSs, indicating that choice of NNS is less important than the reformulation changes required to accommodate the loss of sugar. Reporting impact in terms of calorie density, instead of mass, shows greater reduction in environmental impact when using an NNS or SE and shows how important functional unit is when reporting impact of these products. Conclusion This study is the first to compare food or drink products sweetened with sugar, NNS, or SE. Results show that there is great potential to reduce environmental impact of sweetened drinks and yoghurts. Moreover, the choice of NNS does not greatly affect the environmental impact of either product. Therefore, this research shows that choices relating to replacing added sugar may be based more upon health or formulation needs and less on environmental concerns.