Fluorine

Discovery of Nutritional Importance

Fluorine first attracted nutritional attention in the 1930s, when unsuccessful attempts were made to show that low fluoride intakes produced any kind of pathology in rats and when fluoride was identified as the factor causing a mottled condition of tooth enamel known as “Colorado brown stain” and other such descriptive names (Whitford 1990). It was also noted at that time that fewer dental caries occurred in those individuals with mottled enamel, and subsequently it was discovered that fluoride intakes could be achieved that brought about caries reduction without mottling. As a consequence, water fluoridation was begun as a public health measure in 1945.

In the 1960s, an association was made between high fluoride intake and a reduced incidence of osteoporosis (Messer 1984). However, although the use of pharmacologic amounts of fluoride to prevent bone loss is still being investigated, its usefulness in this regard seems limited. Another round of fluoride confusion came in the early 1970s, when scientists suggested that fluoride was necessary for hematopoiesis, fertility, and growth in mice and rats (Messer 1984). It turned out, however, that this assertion was based on experiments in which animals were not fed optimal diets, and it was later concluded that the effects of fluoride were only achieved through pharmacologic mechanisms.

Dietary Importance

At present, there is no substantive evidence that fluoride is an essential nutrient. The major known biological action of fluoride is its ability to protect against pathological demineralization of calcified tissues, which is not an essential function in the true sense, but a beneficial action delivered through pharmacological mechanisms. Nonetheless, because fluoride was recognized as having beneficial properties through oral intake, ESADDIs for various times in the life cycle were established; for adults, this amount is 1.5 to 4.0 mg (National Research Council 1989).