Vitamin B12 vs Rhodiola
for energy / fatigue
Stronger evidence: tie
Stronger effect: Vitamin B12
Safety: Rhodiola carries a uncertain interaction; Vitamin B12 has none recorded.
For energy / fatigue, the two are evidence-matched; the difference is in effect and safety.
Vitamin B12
grade C low certainty
corrects fatigue when B12 deficiency is present; no energy benefit in replete people
RDA-to-high oral, adults
Rhodiola
grade C low certainty
small reductions in fatigue in stressed adults; studies are short and small
sources: PMID:10000010 · PMID:00000031