Interactions between Fluorine and Aluminum

Interactions between fluorine (as F) and aluminum (as Al) have recently attracted much attention following reports of their possible involvement in Alzheimer’s disease (AD). An inverse correlation has been demonstrated between the incidence and severity of AD and the level of fluorine in drinking water.1-4 Aluminum has long since been implicated in the etiopathology of AD, and neurotoxicity studies have confirmed that it inhibits acetylcholine transferase and dihydropteridine reductase activities, depleting the central nervous system (CNS) of tyrosine and several neurotransmitters. By binding with nucleic acids, aluminum interferes with intracellular protein metabolism.5-7 Cunat et al have studied absorption in situ of aluminum compounds in perfused rat intestine.8 Their findings demonstrate that organic compounds are more potent in modifying aluminum uptake than inorganic ones. The studies of Allain et al9 as well as those of Spencer et al10 have shown that the simultaneous administration of fluorine and aluminum in drinking water increased plasma concentrations of aluminum in rats. The same authors have reported that fluoride enhances the uptake of aluminum, whereas aluminum suppresses the uptake of fluoride. This effect seems to depend on the high affinity of aluminum to fluoride and the formation of complexes in the gastrointestinal tract associated with the breakdown of polymer forms and rapid uptake of aluminum by cells of the intestinal mucosa.11 Glynn et al in their studies on the uptake of aluminum in rats and the effect of fluoride, citrate, or silicate on this process have confirmed the formation of soluble complexes with citrate and fluoride, such as aluminum citrate (97%) and aluminum fluoride (60%). However, changes in absorption of aluminum were observed with citrate only.12