Caffeine vs Vitamin B12

for energy / fatigue

Stronger evidence: Caffeine

Stronger effect: Caffeine

Safety: Caffeine carries a minor interaction; Vitamin B12 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

grade C low certainty

corrects fatigue when B12 deficiency is present; no energy benefit in replete people

RDA-to-high oral, adults

sources: PMID:00000021 · PMID:10000010