Healthy ageing and longevity have emerged as urgent public health priorities amid global population ageing and declining birth rates. This review synthesises empirical evidence highlighting the essential role of diet and nutrition in preventing chronic diseases and supporting functional independence in later life.

The review was organised using a problem-solving approach to address three core questions: “What” evidence links food and nutrition with positive health outcomes; “Why” do specific dietary components affect biological ageing - via mechanisms such as nutrient sensing, inflammation modulation, and caloric restriction; and “How” culturally tailored, person-centred dietary interventions should be developed for better adoption.

Findings from centenarian populations suggest that low-energy (i.e., foods with low energy density, such as fruit and vegetables, whole grains), nutrient-rich, and diverse diets may help prevent or delay age-related diseases, supporting the notion that food could be used as medicine. Moreover, addressing barriers such as food insecurity and limited access to culturally appropriate healthy food options, particularly in low-income and rural communities, is crucial for achieving equitable health outcomes.

Finally, the review calls for integrating personalised nutrition strategies into clinical care and public health initiatives. These efforts can enhance healthspan, improve quality of life, and reduce the broader social and economic burdens associated with ageing populations.