I think this is a distortion of the study. The mice were fed for a period of 6 weeks with NR starting at an age of 24 months. The fact that this short treatment, at such late age results in life extension is quite impressive in my opinion.
Yes but most studies on lifespan does the same and this is why I think they should have included a calorie restriction group. But still 4% is small and its also why i think they didnt even gave this %.. Its significant yes but you cant call that impressive. Even they mention a "slightly increased lifespan".
But knowing what we all discussed here a few pages ago, the solution is more in an holistic approach: NR + pterostilbene + honokiol..
(Also they seems to probably made a mistake somewhere since their result in the text does not match their chart (around 140 / 150 days more in the graph 6G))