Nutrition and ageing: knowledge, gaps and research priorities.

Over the past two centuries human life expectancy has increased by nearly 50 years. Genetic factors account for about one-third of the variation in life expectancy so that most of the inter-individual variation in lifespan is explained by stochastic and environmental factors, including diet. In some model organisms, dietary (energy) restriction is a potent, and highly reproducible, means of increasing lifespan and of reducing the risk of age-related dysfunction although whether this strategy is effective in human subjects is unknown. This is ample evidence that the ageing process is plastic and research demonstrates that ageing is driven by the accumulation of molecular damage, which causes the changes in cell and tissue function that characterise the ageing phenotype. This cellular, tissue and organ damage results in the development of age-related frailty, disabilities and diseases. There are compelling observational data showing links between eating patterns, e.g. the Mediterranean dietary pattern, and ageing. In contrast, there is little empirical evidence that dietary changes can prolong healthy lifespan and there is even less information about the intervention modalities that can produce such sustainable dietary behaviour changes. In conclusion, current research needs include (1) a better understanding of the causal biological pathways linking diet with the ageing trajectory, (2) the development of lifestyle-based interventions, including dietary changes, which are effective in preventing age-related disease and disability and (3) the development of robust markers of healthy ageing, which can be used as surrogate outcome measures in the development and testing of dietary interventions designed to enhance health and well-being long into old age.