Milking the milk: Exploiting the full potential of milk constituents for nature-derived delivery systems

Background: Nowadays, incrising global demand for milk and milk-derived products throughout the world has led to a massive growth of the dairy sector, and with it an increase in the associated environmental impacts. Milk surplus and by-products disposal represent a serious burden in this scope. Thus, it is essential to improve the valorization of this resource. Scope and approach: In light of milk's natural delivery function, this review provides an up-to-date collection of the milk-derived delivery systems (MDDS). Special focus is given to the colloidal structures found naturally in bovine milk or reassembled architectures produced with materials derived from milk (milk fat globules, caseins, whey proteins and extracellular vesicles). Furthermore, this review takes a critical perspective on public health, environmental and regulatory issues related to milk production and consumption. Key findings and conclusions: Milk has been shown to be a safe and low-cost source of materials with huge potential as delivery systems, applied both in nutrition and medicine. However, there are hurdles to overcome prior to their implementation. From a health perspective, testing carrier biocompatibility and considering milk intolerance and allergy is crucial. Dairy farming is associated with serious environmental burdens, which have been leading to increasing support for animal-free diets and products. The lack of standardized methods for producing these MDDS also hampers their translation. Thus, more research is still needed to surpass these problems and allow us to fully exploit milk's potential.