Aluminum bioavailability from drinking water is very low and is not appreciably influenced by stomach contents or water hardness

The objectives were to estimate aluminum (Al) oral bioavailability under conditions that model its consumption in drinking water, and to test the hypotheses that stomach contents and co-administration of the major components of hard water affect Al absorption. Rats received intragastric Al-26 in the absence and presence of food in the stomach and with or without concomitant calcium (Ca) and magnesium (Mg) at concentrations found in hard drinking water. The use of Al-26 enables the study of Al pharmacokinetics at physiological Al concentrations without interference from Al-27 in the environment or the subject. Al-27 was intravenously administered throughout the study. Repeated blood withdrawal enabled determination of oral Al-26 bioavailability from the area under its serum concentration x time curve compared to serum Al-27 concentration in relation to its infusion rate. Oral Al bioavailability averaged 0.28%. The presence of food in the stomach and Ca and Mg in the water that contained the orally dosed Al-26 appeared to delay but not significantly alter the extent of Al-26 absorption. The present and published results suggest oral bioavailability of Al from drinking water is very low, about 0.3%. The present results suggest it is independent of stomach contents and water hardness. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.