Fluoride: Intake and Metabolism, Therapeutic and Toxicological Consequences

Fluoride (F) is present in all soils, water, plants, and animals. The main sources of F intake are diet and the unintentional swallowing of fluoridated dental products. 80-90% of ingested F is absorbed from the gastrointestinal tract by passive diffusion. Almost half of that is excreted in the urine, and the remainder is incorporated in the calcified tissues, which contain 99% of the F in the body. F is the most successful active agent against dental caries. It is also one of the few agents that can stimulate bone cell proliferation and therefore may be of benefit in optimizing bone mineral density, important in maintaining bone health throughout life. Conversely, disturbances of enamel development (dental/enamel fluorosis) and bone homeostasis (skeletal fluorosis) are consequences of excessive retention of F in the body. Several factors can affect F metabolism and consequently F retention, including acid-base disturbance, altitude, physical activity, diet, and genetic predisposition.