What to take for energy / fatigue

Graded by the strength of the evidence — strongest first. Nothing here is sold to you.

Irongrade A— reliably reduces fatigue when iron deficiency / IDA is present; no benefit when iron-replete

CoQ10grade A— Meta-analysis of 13 RCTs (n=1,126) found CoQ10 supplementation significantly reduced fatigue scores versus placebo (Hedges' g = -0.398, 95% CI: -0.641 to -0.155, p = 0.001). Benefits were consistent in healthy and diseased participants, and greater reductions were associated with higher daily doses and longer durations. The effect was significant for CoQ10-only formulations but not CoQ10 compounds.

Caffeinegrade B— reduces perceived fatigue; tolerance develops with regular use

Ashwagandhagrade B— Ashwagandha supplementation was more efficacious than placebo for improving fatigue/recovery variables in healthy individuals.

Rhodiolagrade C— small reductions in fatigue in stressed adults; studies are short and small

CoQ10grade C— limited evidence for general fatigue; clearer in specific conditions (e.g., statin myalgia, mitochondrial disorders)

Creatinegrade C— may reduce mental fatigue, especially under sleep deprivation or stress

Vitamin B12grade C— corrects fatigue when B12 deficiency is present; no energy benefit in replete people

Irongrade D— 21-study review: iron supplementation associated with improved fatigue scores (p-values only, no CI/n given) in non-anemic iron deficiency; the review's own meta-analyses were "limited" for most outcomes examined.