Many illnesses, such as schizophrenia, Alzheimer’s disease, Parkinson’s disease and bipolar disorder are associated with oxidant stress. Yet, increasing levels of free antioxidants by supplementing with more than RDA amounts of vitamin E, beta-carotene and vitamin C does not treat these illnesses.
Increasing levels of free antioxidants via supplmentation could be much worse than useless. Before iron can be absorbed iron must be reduced from Fe3+ to Fe2+. Antioxidants like vitamin C, vitamin E , beta-carotene and quercetin could one way or other promote the reduction of Fe3+ to Fe2+ in the gastrointestinal tract which would increase absorption. The goal, however, is to delay iron absorption as long as feasible.
There is oxidant stress in lots of illnesses but this could be due to dysregulation of selenoproteins and dysregulation of iron metabolism which would not be fixed by increasing levels of free antioxidants with supplemental vitamin C, vitamin E , beta-carotene, quercetin etc.
Supplementing with free antioxidants could be associated with very subtle but serious mineral dysregulations which would basically be undiagnosable.