Parenteral nutrition components interfere in the silicon protection of aluminum toxicity

Aluminum and silicon are contaminants found in formulations used to prepare parenteral nutrition. Both elements are leached from glass containers, mainly during the heating cycle for sterilization. Insoluble and biologically inactive species of hydroxyaluminosilicates have been shown to form in solutions containing Al and Si. Therefore, this interaction may play an important role in protecting the body against Al toxicity. In this study, the bioavailability of Al in the presence of Si, calcium gluconate (Gluc.) and potassium phosphate (Phosf.) was investigated in rats. The rats were divided into 10 groups of 5 animals each: control, Al, Si, Al + Si, Gluc, Gluc + Al, Gluc + Al + Si, Phosf, Phosf + Al and Phosf + Al + Si. The doses, consisting of 0.5 mg/kg/day Al and 2 mg/kg/day Si in the presence ou absence of Gluc. or Phosf., were intraperitoneally administered for 3 months. Tissues were analyzed for Al and Si content. Al accumulated in the liver, kidneys, and bones, and the simultaneous administration of Si decreased Al accumulation in these tissues. The presence of Si reduced the amount of Al present by 72% in the liver, by 45% in the kidneys and by 16% in bone. This effect was lees pronounced in the presence of parenteral nutrition compounds though. Si tissue accumulation was also observed, mainly when administered together with phosphate. These results suggest that Si may act as a protector against Al toxicity, by either reducing Al absorption or increasing its excretion, probably through hydroxyaluminosilicates formation. The presence of calcium gluconate and potassium phosphate decrease or inhibit this effect.