Metabolism and Possible Health Effects of Aluminum

Abstract

Literature regarding the biochemistry of aluminum and eight similar ions is reviewed. Close and hitherto unknown similarities were found. A hypothetical model is presented for the metabolism, based on documented direct observations of Al3+ and analogies from other ions. Main characteristics are low intestinal absorption, rapid urinary excretion, and slow tissue uptake, mostly in skeleton and reticuloendothelial cells. Intracellular Al3+ is probably first confined in the lysosomes but then slowly accumulates in the cell nucleus and chromatin. Large, long-lived cells, e.g., neurons, may be the most liable to this accumulation. In heterochromatin, Al3+ levels can be found comparable to those used in leather tannage. It is proposed that an accumulation may take place at a subcellular level without any significant increase in the corresponding tissue concentration. The possible effects of this accumulation are discussed. As Al3+ is neurotoxic, the brain metabolism is most interesting. The normal and the lethally toxic brain levels of Al3+ are well documented and differ only by a factor of 3-10. The normal brain uptake of Al3+ is estimated from data on intestinal uptake of Al3+ and brain uptake of radionuclides of similar ions administered intravenously. The uptake is very slow, 1 mg in 36 years, and is consistent with an assumption that Al3+ taken up by the brain cannot be eliminated and is therefore accumulated. The possibility that Al3+ may cause or contribute to some specific diseases, most of them related to aging, is discussed with the proposed metabolic picture in mind.

In‐vitro dissolution of magnesium–calcium binary alloys: Clarifying the unique role of calcium additions in bioresorbable magnesium implant alloys

“…The development of suitable biodegradable implant alloys is a multidisciplinary challenge, since freedom in alloy design must be confined to a range of alloying additions that are nontoxic in a medical sense. This rules out a large number of alloying elements common to commercial Mg alloys, including appreciable amounts of rare earth elements, some heavy metals, and to a large extent, aluminium 22, 23. A promising and biocompatible element is calcium (Ca), and while some limited studies to date have reported the use of Ca,24–26 a systematic and fundamental study of the role of Ca additions upon dissolution of Mg alloys in vitro is warranted and timely.…”

Evaluation of aluminium concentrations in samples of chocolate and beverages by electrothermal atomic absorption spectrometry

“…Several studies demonstrated that the element is involved in the development of both dementia (Graves et al 1990, Martin 1990, Wisniewski et al 1990) and osteomalacia (Drueke 1980, Costantini et al 1984, Zhu et al 1990) in patients undergoing dialysis, since it enters the blood stream directly from the water used in the process (Trapp 1983, Alfrey 1986). Although Al has been shown to be potentially toxic for the healthy population (Mayor et al 1977, Ganrot 1986, Flaten 1990), its bioavailabilit y is very low owing to both its low absorption by the gastrointestinal tract and its rapid urinary excretion (Alfrey 1989, Lote 1991. Problems can arise if the protection aOE orded by the gastrointestinal tract is circumvented.…”

Protein Side Chains Facilitate Mg/Al Exchange in Model Protein Binding Sites

“…Mg II seems to be one of the most affected cations, [9][10][11] since the two cations are of similar size, a factor that dominates over charge identity in metal competition. [9,12,13] Numerous examples of Al III inhibition of Mg II -dependent metalloenzymes have been reported. Hexokinase, adenylate cyclase, 3,5-cyclic nucleotide phosphodiesterase, acid and alkaline phosphatases, and acetylcholinesterase are well-documented examples [10] of Mg II substitution by Al III .…”