Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular “reactive oxygen species” (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation. We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation). The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible. This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, etc…

💡 Research Summary

The paper argues that the combination of reactive oxygen species (ROS) – specifically super‑oxide (O2·‑) and hydrogen peroxide (H2O2) – with poorly liganded iron (Fe2+ or Fe3+ that is not tightly bound to proteins or chelators) creates a catalytic cycle that generates the hydroxyl radical (·OH) via Fenton and Haber‑Weiss reactions. The hydroxyl radical is extremely reactive, causing indiscriminate damage to lipids, proteins, nucleic acids and other cellular components, which in turn fuels chronic inflammation. The authors review a broad spectrum of experimental and clinical data showing that iron‑catalysed radical production is present at the sites of many progressive diseases: atherosclerotic plaques, myocardial infarction, heart failure, hypertension, diabetes, metabolic syndrome, neurodegenerative disorders such as Alzheimer’s and Parkinson’s disease, and even normal ageing. In each case, iron accumulates in the lesion or plaque, and markers of oxidative damage correlate with disease severity.

The paper also discusses why antioxidant supplementation (vitamin C, vitamin E, polyphenols, etc.) has produced mixed or disappointing results in clinical trials. Antioxidants can scavenge super‑oxide or hydrogen peroxide, but they do not remove the underlying catalytic iron, and in some circumstances they can even reduce Fe3+ to Fe2+, thereby enhancing the Fenton reaction. Consequently, the system behaves as a multivariate network where the removal of a single node does not necessarily break the pathological loop.

Effective therapeutic strategies, according to the authors, must therefore target the iron component. They review natural iron‑binding ligands (e.g., lactoferrin, ferritin, polyphenolic compounds such as quercetin, curcumin, and flavonoids) and synthetic chelators (deferoxamine, deferiprone, deferasirox, and newer bifunctional molecules that combine antioxidant and chelating functions). Pre‑clinical studies demonstrate that appropriate chelation reduces hydroxyl‑radical formation, limits lipid peroxidation, preserves mitochondrial function, and attenuates disease progression in animal models of atherosclerosis, diabetic nephropathy, and neurodegeneration.

A key conceptual point is the systems‑biology perspective: physiological observables (e.g., blood pressure, cognitive decline, serum lipid peroxidation) often have multiple molecular contributors. Studying them in isolation leads to inconsistent causality patterns, which explains the heterogeneous outcomes of antioxidant trials. The authors propose an integrated model where (i) aerobic metabolism inevitably produces ROS, (ii) insufficient sequestration of iron allows ROS‑iron interaction, (iii) the resulting hydroxyl radical drives chronic inflammation and tissue damage, and (iv) iron chelation, possibly combined with modest antioxidant support, can interrupt this loop.

The paper concludes that inappropriate iron chelation is a major, yet under‑appreciated, contributor to the aetiology of vascular, metabolic, neurological and age‑related degenerative diseases. It calls for more rigorous clinical studies of iron‑targeted therapies, better biomarkers of labile iron pools, and a shift from the “antioxidant‑only” paradigm to a “iron‑and‑oxidative‑stress” paradigm in both research and therapeutic development.