The influence of dissolved silicate on the physiological chemistry of aluminium, studied in humans using tracer 26Al and accelerator mass spectrometry

Abstract Trace quantities of aluminium, spiked with 26 Al, were administered twice, to each of two subjects, in citrate-containing drinks (4 or 50 mmol/l). Silicate (0.5 mmol/l), in the form of a Si-rich natural mineral water, was added to the dose on the second occasion for each subject. Al-uptake and excretion were determined from AMS measurement of 26 Al in blood plasma (whole plasma and the low molecular weight fraction) and urine for up to 7 days. Citrate markedly enhanced Al uptake, as previously observed. A major effect of silicate was to enhance the rate of Al elimination, probably through an increase in the LMW plasma fraction (5% with no Si; 7.5% with Si). Aluminium uptake appeared to be only slightly affected by Si, and showed opposite effects depending on citrate concentration. With low citrate, Si marginally increased Al uptake, whilst with high citrate, Al uptake appeared to be reduced by the presence of Si.