Understanding environmental impacts of complete food supply chains is important for the food industry to help devise strategies for reducing the impacts of current and future products. Breakfast cereals are one of the most important foods consumed in many countries, but their environmental impacts are currently unknown. Therefore, this study explores the environmental sustainability issues in the food–energy–water nexus by considering breakfast cereals manufactured by one of the world’s largest producers, Kellogg Europe. A life cycle assessment has been carried out for these purposes with the aim of helping the Company to integrate environmental sustainability considerations into the design of their products and packaging. The results indicate that the average global warming potential (GWP) of Kellogg’s breakfast cereals is 2.64 kg CO2 eq. per kg of product. The main GWP hotspots are the ingredients (48%) and energy used in the manufacturing process (23%); packaging and transport contribute 15% each. Rice is the single largest contributor to the GWP of the ingredients (38%). The manufacturing stage is the main contributor of primary energy demand (34%), while the ingredients are responsible for more than 90% of the water footprint. The ingredients are also the main contributors to most other environmental impacts, including land use (97%), depletion of elements (61%), eutrophication (71%), human toxicity (54%) and photochemical smog (50%). The impacts from packaging are high for freshwater and marine toxicity. The contribution of transport is significant for depletion of elements and fossil resources (23%), acidification (32%), ozone depletion (28%) and photochemical smog (24%). Improvement opportunities explored in the paper include better agricultural practices, recipe modifications, improved energy efficiency of manufacturing processes and use of alternative packaging. Impacts from consumption are also discussed.

This study uses Taiwan's WEF nexus as a case study to demonstrate how the resource flow and associated environmental impact of the WEF nexus can be assessed as basis for evaluating strategies for promoting the sustainable use of natural resources. In this study, material flow analysis (MFA) and life-cycle assessment (LCA), were combined. The MFA was used to examine the interdependence of the three natural resources, and the LCA was used to evaluate the environmental impacts of the WEF system. The WEF nexus analysis shows that tap water supply, oil refining, the cogeneration of steam and electricity, thermoelectric power plants, irrigation, animal husbandry, and aquaculture are the main interwoven nodes and have the most prominent impact on the three natural resources. When the unit products from the WEF system were determined, LCA was implemented for these products to identify 15 types of environmental impacts. The environmental impacts for the WEF system were then calculated based on the use of unit products. The results of LCA showed that the most prominent impacts are the impact of public electricity on climate change; oil products on ozone depletion and ionizing radiation; tap water on metal depletion; and animal husbandry on terrestrial ecotoxicity. Based on the assessment of the alternative resource management strategies, if both water and energy policies are modified simultaneously, the impact of the overall WEF system on most environmental impact categories could be reduced.