Manipulation of in vivo iron levels can alter resistance to oxidative stress without affecting ageing in the nematode C. elegans

► Here we test whether iron-catalyzed oxidative damage contributes to organismal ageing. ► We develop new methodologies to measure free iron in vivo in C. elegans. ► Moderate iron supplementation can increase oxidative damage without reducing lifespan. ► Iron chelation or increasing ferritin levels increase resistance to oxidative stress but do not increase lifespan. ► Our findings argue against the oxidative damage theory of ageing.