Bioavailability of fluoride from dietary sepiolite in the lamb

Nine weeks after weaning, 12 lambs were randomised to 2 groups, each consisting of 6 animals. One group received a diet containing 213.9 mg/kg of fluor (F) in the form of sodium fluoride (NaF) and the other group received a diet containing 212.3 mg/kg of fluor in the form of sepiolite. The 24 h time courses of plasma fluoride concentrations showed that after feeding the average peak plasma concentration of the NaF-fed group was 0.75 microgram F/ml; that of the sepiolite-fed group was 0.35 microgram F/ml. The 12-h area under the plasma concentration curve (AUC) values in the NaF-fed group were higher with statistical significance (P less than 0.001) at each time point. Compared with fluoride from NaF, the relative bioavailability of fluoride from sepiolite was found to be very weak.