Nutrition

Diet as a whole, encompassing food composition, calorie intake, and the length and frequency of fasting periods, affects the time span in which health and functional capacity are maintained. ^[1] In recent years nutrition research in relation to health outcomes has changed from focusing exclusively on single nutrients to considering combinations of foods rather than nutrients in isolation, promoting interest in the actions of total dietary patterns. ^[2] The specific types or food sources of dietary fat, protein, and carbohydrates are more important in influencing chronic disease risk and mortality than their quantity. ^[3]

The mTOR pathway integrates environmental cues such as growth factor signals and nutritional status to direct cell growth, and its dysregulation has been implicated in metabolic disorders, neurodegeneration, cancer and ageing. ^[4] Different forms of fasting, protein restriction and specific reductions in essential amino acids selectively impact key nutrient-sensing geroprotective signalling pathways including AKT, FOXO, mTOR, NAD+, AMPK and FGF21 that promote healthy longevity. ^[5] Longevity can be linked to conserved growth and metabolic pathways, and a longevity diet can be defined based on a multi-pillar approach adjusted for age and health status to optimize lifespan and healthspan in humans. ^[1]

Dietary restriction with adequate nutrition is the gold standard for delaying ageing and extending healthspan and lifespan in diverse species, including rodents and non-human primates. ^[5] Traditional diets such as the Mediterranean, Nordic, and Okinawa and contemporary patterns such as the DASH diet have been associated with lower mortality and healthy longevity. ^[3] Combining a healthy diet with other lifestyle factors could extend disease-free life expectancies by 8-10 years. ^[3] After the Seven Countries Study, many prospective observational studies and trials reinforced the beneficial effects associated with higher adherence to the Mediterranean diet for the prevention or management of age-associated non-communicable diseases such as cardiovascular, metabolic, and neurodegenerative diseases and cancer. ^[6]

Nutritional factors have a major impact on the risk of age-associated chronic non-communicable diseases and mortality. ^[2] Malnutrition and dehydration are widespread in older people, and it is recommended that all older persons be routinely screened for malnutrition in order to identify existing risk early. ^[7] Maintaining a healthy weight throughout life is pivotal for healthy aging and longevity, mirroring the benefits of lifelong, moderate calorie restriction in today's obesogenic food environment. ^[3]