Tissue Lanthanum Deposition and Phosphorus Balance in Rats with Long-term Dietary Administration of Lanthanum Carbonate

Abstract

To confirm whether lanthanum carbonate can be used as a harmless inducer to decrease the bioaccessibility of phosphorus during the digestion process, tissue lanthanum deposition and phosphorus balance as well as liver and kidney functions in serum biochemical tests were examined in rats with long-term dietary administration of lanthanum carbonate. Male 8-week-old Wistar rats were fed a basal diet or the basal diet supplemented with 0.225 or 0.45% lanthanum as lanthanum carbonate for 26 weeks. Lanthanum administration did not influence body and several organ weights as well as liver and kidney functions and iron metabolism in serum biochemical tests. In rats administered lanthanum, a small quantity of lanthanum (200 to 1500 ng/g) was detected in the liver, kidney and femur. Lanthanum was not clearly detected in the brain. Differences in organ lanthanum between 0.225% and 0.45% administration groups were not significant; lanthanum accumulation in the body is low and may be almost saturated to a constant level regardless of the dosage or the period of administration. Lanthanum administration increased fecal phosphorus excretion but did not change serum phosphorus concentration. Equilibrium was maintained in phosphorus balance because urinary phosphorus excretion was decreased in rats with lanthanum administration. Since a serious adverse effect with lanthanum itself was not observed, lanthanum carbonate can be used as a harmless inducer to decrease the bioaccessibility of phosphorus during the digestion process in animal experiments.