Consumers are increasingly interested in the sustainability of food products, but so far, no specific European Union (EU) legislation has been developed to harmonise sustainability claims. We analyse which efforts already undertaken within the EU dealing with sustainability claims on products apply to sustainable food claims. We show that whilst sustainability can address three different dimensions (environmental, social and economic), it is crucial to clearly define sustainability in order to allow for the development of concrete regulations and guidance documents. EU legislative initiatives so far seem to be focused on environmental aspects, whilst Member States approach sustainability more broadly. At the same time, substantiation methods can only be successful when sustainability is well defined. We conclude that whilst there is a large range of initiatives taken at different levels, the foundation of these initiatives remains weak when there is no clear scope of terminology nor clarification of substantiation requirements. Currently existing self-regulatory initiatives could support protecting consumers from misleading claims by providing specific provisions for (food) business operators on how to make sustainability claims. Only when claims can be trusted and understood by consumers will they be able to make more sustainable purchase decisions. This plays an important role in the overall policy objective of the EU of climate neutrality by 2050.