V. Herbert et al., MOST FREE-RADICAL INJURY IS IRON-RELATED - IT IS PROMOTED BY IRON, HEMIN, HOLOFERRITIN AND VITAMIN-C, AND INHIBITED BY DESFEROXAMINE AND APOFERRITIN, Stem cells, 12(3), 1994, pp. 289-303
Iron is a double-edged sword. In moderate quantities and leashed to pr
otein, it is an essential element in all cell metabolism and growth, b
ut it is toxic when unleashed [1]. Because of its ability to switch ba
ck 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 anti-carcinog
ens, many of which act by generating oxygen radicals, which initiate d
egenerative processes related to cancer, heart disease and aging (the
''oxygen radical hypothesis of aging'') [2]. Among these many dietary
chemicals are many redox agents, including vitamin C and beta carotene
[3]. Free radical damage is produced primarily by the hydroxyl radica
l (.OH) [4, 5]. Most of the 'OH generated in vivo comes from iron-depe
ndent reduction of H2O2 [4, 5]. Supporting too much iron as a free rad
ical-generating culprit in the risk of cancer, NHANES I data indicated
that high body iron stores, manifested by increased transferrin satur
ation, are associated with an increased cancer risk [6]. Other data [1
] shows an increased heart attack risk.