Vitamin B12 vs NMN

for energy / fatigue

Stronger evidence: Vitamin B12

Stronger effect: unknown

Safety: No notable interactions recorded for either.

For energy / fatigue, Vitamin B12 has the stronger evidence grade.

grade C low certainty

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

RDA-to-high oral, adults

not well studied very-low certainty

not adequately studied for fatigue/energy outcomes in humans

sources: PMID:10000010