Occurrence, exposure, effects, recommended intake and possible dietary use of selected trace compounds (aluminium, bismuth, cobalt, gold, lithium, nickel, silver)

Background: Minerals, metals, clays and rocks were widely used by physicians in the past. However, it was and it is well known that some inorganic elements at high dosage may have curative effects but also serious toxicity. The effects at low or ultra-low concentrations, on the contrary, are less documented, but the idea that low dosage supplementation might be beneficial to human health is widespread even in the present period. Methods: The main information about aluminium, bismuth, cobalt, gold, lithium, nickel and silver was selected and evaluated from a vast body of medical literature. Results: In modern times, most elements are proposed for human use at levels comparable with normal dietary intake, probably for precautionary considerations. Conclusion: Some inorganic trace compounds might have unexpected effects at extremely low dosages, but scientific demonstrations of beneficial effects of supplementation are mostly not available in the medical literature.