Mixing vitamin C with iron in a test tube has been shown to trigger a chemical reaction that can generate the production of some very damaging free radicals, such as lipid peroxides. Within the body, iron is not found in a free form in high concentrations; most is bound to special proteins such as ferritin, transferrin, and lactoferrin.

Even if a person has hemochromatosis — a condition in which iron levels in the blood and tissues are very high — high-dose vitamin C (ascorbate) has been demonstrated to be safe.

There is some evidence that with conditions in which there is a deficiency of these special protective iron-carrier proteins — such as with Parkinson’s disease — high levels of vitamin C could increase lipid peroxidation. Yet studies of Alzheimer’s brains, which also have high free iron levels, found that high vitamin C offered protection against lipid peroxidation.

The best evidence seems to indicate that vitamin C is protective against iron toxicity.

Vitamin C does increase iron absorption from the intestines. For this reason, it should always be taken between meals.

Normally, flavonoids in vegetables and fruits bind iron and prevent its absorption, but ascorbate can even increase iron absorption from vegetables.

Iron supplements should not be taken at the same time of day as ascorbate supplements, as it will convert the iron to a more destructive valence.