The link between diet and health has been recognized since the Grecian period; as Hippocrates said, "Let food be your medicine and medicine be your food". Although the primary goals of diet are meeting nutritional requirements and providing energy, there is increasing awareness that a correct and balanced diet may prevent the insurgence of diet-related pathologies and/or improve well-being and life expectancy, also reflecting on the ageing process. Research on the interaction among nutrients, gut microbiota and host metabolism is presently unravelling the molecular mechanisms underlying the positive and negative effects of traditional diets on health and ageing, providing useful information for the design of innovative foods targeting specific needs and segments of the population. The food supply chain plays a key role in ensuring quality and safety through both comprehensive quality management and inspection systems and a focused innovation process mainly devoted to the creation of functional foods. However, innovation and scientific development pose a problem of information asymmetry towards final consumers; thus, regulatory aspects and private and public communication strategies must be efficiently developed.