Seven and a half years of low-dose antioxidant supplementation is associated with a reduction in total cancer incidence and mortality in men, but not in women, indicating a gender-specific effect of long-term antioxidant intake on cancer outcomes.

In men with low levels of beta-carotene, daily antioxidant supplements raise blood levels of this compound, which neutralizes harmful molecules that damage DNA. Less DNA damage means fewer cells turn into cancer cells, lowering the chance of developing cancer and dying from it. Women do not experience this benefit because their baseline levels are already high enough that supplements do not change their oxidative stress or DNA damage rates.