The current, most accepted, way to increase life span is CR, Caloric Restriction (eating less). A tough regimen for some of us to follow- I am a "foodie", I live in the foodie capitol of the US, San Francisco. It also has some drawbacks- anecdotal reports indicate CR affects libido negatively.
The upshot of this article is that reduction of a specific diet component (yeast) rather than overall calorie restriction resulted in a longer life span (in fruitflies).
"Professor Linda Partridge said: "Altogether these results make a strong case that calories per se are not the salient factor in prolonging life-at least in fruitflies. The dramatic impact of reducing yeast suggests that protein or fat plays a greater role in fly longevity than sugar. This suggests that yeast and sugar trigger different metabolic pathways with different effects on life span"