2 forms studied

Does iron help with low stamina?

Yes — but only in one form. Ferrous Sulfate is the one that was tested, and the others sold for this do not carry the same evidence.

Form by form

Strongest first. Evidence for one salt or ester is not evidence for another, so each is rated on its own trials.

Trials used 18–36 mg · 1 study

Trials used 18–36 mg · 3 studies · tested as Ferrous Sulfate

Worth knowing before you buy. Iron Bisglycinate is widely sold for low stamina, but the trials behind that use tested ferrous sulfate instead.