Trans Fatty Acid Isomers: Health, Technological, and Regulatory Perspectives for Sustainable Fat Reformulation

For decades, industrial trans fatty acids (iTFAs) have remained a critical focus of the scientific community, the food industry, and regulatory authorities because of their well-established role in the development of cardiovascular diseases, metabolic disorders, and chronic systemic inflammation. Rather than providing a descriptive overview, this review critically synthesizes current evidence on the elimination of industrial TFAs by integrating health, technological, regulatory, and sustainability perspectives into a comprehensive interdisciplinary analysis. The review outlines the biochemical characteristics and dietary sources of trans fatty acid isomers, highlighting the continuing scientific debate regarding the differential health effects of industrially produced and naturally occurring ruminant-derived TFAs. It also examines the evolution of scientific evidence that led to major regulatory actions by international organizations, including the World Health Organization (WHO) and the European Commission, resulting in legally binding restrictions that have substantially reduced industrial TFA intake and improved public health. Particular emphasis is placed on the critical assessment of current fat reformulation strategies, considering not only their technological functionality but also their nutritional quality, long-term metabolic implications, and contribution to sustainable food systems. Full hydrogenation, fractionation, chemical and enzymatic interesterification, and oleogelation are comparatively evaluated with respect to their advantages, limitations, and potential technological, nutritional, and environmental trade-offs. In addition, lipid microencapsulation is discussed as an emerging strategy for protecting oxidation-sensitive polyunsaturated fatty acids (PUFAs), thereby facilitating their incorporation into functional foods while maintaining nutritional quality. Unlike previous reviews that primarily focus on health outcomes or individual processing technologies, this review systematically integrates the sustainability dimensions of alternative fat modification approaches, including resource efficiency, energy consumption, clean label product development, and circular economy principles. Furthermore, it identifies current knowledge gaps related to the long-term metabolic safety, industrial scalability, and environmental performance of emerging lipid technologies. By combining these complementary perspectives, the review provides a comprehensive interdisciplinary synthesis that supports evidence-based fat reformulation and offers practical guidance for researchers, food manufacturers, and policy makers seeking to develop safer, nutritionally improved, technologically functional, and environmentally sustainable lipid systems.