Nutrition and longevity - From mechanisms to uncertainties.

Genetic, environmental, and lifestyle factors primarily determine the lifespan of humans. From these, nutrition is a key component affecting our health, and several studies particularly in model organisms and rodents have shown that nutrition has also the potential to increase lifespan. This review, therefore, aimed to summarize and discuss the most important nutritional components and diets which have been repeatedly associated with longevity. A brief summary of mechanistic factors involved, like for example mTor, IGF-1, and autophagy, will also be presented. Finally, the association of foods and diets with all-cause mortality will be summarized by conducting a mini umbrella review of available meta-analyses. The main conclusions of this review are that caloric restriction without malnutrition, methionine restriction, lower protein intake or supplementation of spermidine are major life-extending factors, in model organisms or rodents. In humans, certain healthy foods are associated with longer telomere length, and reductions in protein intake with lower IGF-1 levels, respectively, both relations being associated with longer lifespan. Furthermore, a high intake of whole grains, vegetables, fruits, nuts, and also coffee is associated with a reduced risk for all-cause mortality whereas a high intake of (red) meat and especially processed meat is positively related to all-cause mortality. In addition, the Mediterranean and also high-quality diets are associated with reduced all-cause mortality risk.