Stem Cells. 1994 May;12(3):289-303.
Most free-radical injury is iron-related: it is promoted by iron, hemin, holoferritin and vitamin C, and inhibited by desferoxamine and apoferritin.
Herbert V, Shaw S, Jayatilleke E, Stopler-Kasdan T.
Nutrition Center, Mount Sinai, Bronx, New York.
Iron is a double-edged sword. In moderate quantities and leashed to protein, it is an essential element in all cell metabolism and growth, but it is toxic when unleashed. Because of its ability to switch back and forth between ferrous and ferric oxidation states, iron is both a strong biological oxidant and reductant. The human diet contains a multitude of natural chemicals which are carcinogens and anticarcinogens, many of which act by generating oxygen radicals, which initiate degenerative processes related to cancer, heart disease and aging (the "oxygen radical hypothesis of aging"). Among these many dietary chemicals are many redox agents, including vitamin C and beta carotene. Free radical damage is produced primarily by the hydroxyl radical (.OH). Most of the .OH generated in vivo comes from iron-dependent reduction of H2O2. Supporting too much iron as a free radical-generating culprit in the risk of cancer, NHANES I data indicated that high body iron stores, manifested by increased transferrin saturation, are associated with an increased cancer risk. Other data shows an increased heart attack risk. ************************************************************My take on this ( would like to read entire article). "Supporting TOO MUCH iron" is key here. How do they define "too much"? What levels are they referring to? Without specific numeric values ( which may be included in the entire piece), this is difficult to interpret. As the author states, iron is potentially toxic due to the catalyzation of Hydrogen Peroxide into free radicals. Protein binding stops this process. If they are saying Vitamin C increases iron absorption, it does, yet they do not say the DEGREE to which it does this. There is a large difference between normal iron levels and those found in iron overload ( ie hemochromatosis), or, as the authors state, even " high body iron stores". Yes, a large portion of those with hemochromatosis develop liver malignancies if left untreated, however, there is a wide range between normal iron levels and iron overload. It is difficult to absorb iron, fortunately ( both heme and non-heme forms). The crux here is specifying the DEGREE to which specific amounts of C elevate the types of iron. It may simply be a mild elevation, and there has never been any correlation with hemochromatosis or hemosiderosis in patients consuming large amounts of C . How much C is given, what are the normal ranges, what is the specific elevation, what other blood parameters were affected, ad infinitum? Did participants have normal iron levels, or clinical iron overload disorders? One should never take multi vitamins with iron for this reason. Divers and astronauts also have iron elevation difficulties due to pressure factors. Supposedly this is why people who regularly donate blood live longer...they reduce iron levels. It might be an interesting search to try to correlate elevated iron levels with megadose C consumption. There are orthomolecular physicians that give hundreds of mgs of C intravenously, and there has never been a reported case of overload. If you are taking megadoses of anything, you should be monitoring blood. Be certain to request serum ferritin. Very interesting post. Lisa