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 co nditions that model its consumption in drinking water, and to test the hypo theses 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 concomitan t calcium (Ca) and magnesium (Mg) at concentrations found in hard drinking water. The use of Al-26 enables the study of Al pharmacokinetics at physiol ogical 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 bioavailabil ity from the area under its serum concentration x time curve compared to se rum Al-27 concentration in relation to its infusion rate. Oral Al bioavaila bility 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 publish ed results suggest oral bioavailability of Al from drinking water is very l ow, about 0.3%. The present results suggest it is independent of stomach co ntents and water hardness. (C) 2001 Elsevier Science Ireland Ltd. All right s reserved.