Extending healthy ageing: nutrient sensitive pathway and centenarian population

Ageing is an irreversible process associated with numerous physiological alterations across multiple organ systems. Molecular studies in model organisms have identified several longevity genes and pathways which can extend the lifespan. Although many data are available from these animal models, in humans the situation is much more complex. Certainly human ageing is due to interactions between genetic and epigenetic factors but in addition to the genetic background, successful or unsuccessful ageing is also determined by environmental factors associated with social structure, culture and lifestyle. A fascinating, rapidly emerging concept in the biomedical sciences which may help establish a novel and innovative intellectual framework in biomedical research is the 'positive biology paradigm' [1]. Rather than making disease the central focus of researchers' efforts, positive biology seeks to understand the causes of positive phenotypes and which biological mechanisms would explain health and well-being. For instance, a better understanding of exemplars of human exceptional longevity could be a goal of positive biology and could create real benefits for those who are more vulnerable to disease and disability. Life expectancy for humans has more than doubled in the last two centuries and in some European countries it is estimated that by 2050 the proportion of persons older than 60 will rise from 20% to almost 40% [2] and the number of centenarians will be nearly 3.2 million world-wide [3]. Therefore, even though scientists have elucidated many biological ageing processes providing new strategies that may help to slow the rate of ageing in humans, it is imperative to emphasize research on healthy ageing in order to reduce frailty and disability associated with the "normal" ageing process. Resistance against cellular stress and environmental insults can help promote a more successful ageing process that results in a longer and healthier lifespan. Despite the fact that gen