Caffeine vs NMN

for energy / fatigue

Stronger evidence: Caffeine

Stronger effect: unknown

Safety: Caffeine carries a minor interaction; NMN has none recorded.

For energy / fatigue, Caffeine has the stronger evidence grade.

grade B moderate certainty

reduces perceived fatigue; tolerance develops with regular use

40–200 mg

not well studied very-low certainty

not adequately studied for fatigue/energy outcomes in humans

sources: PMID:00000021