[7] Fluorine is not considered to be an essential nutrient, but the importance of fluorides for preventing tooth decay is well-recognized,[8] despite the effect is predominantly topical.

[9] Prior to 1981, the effect of fluorides was thought to be largely systemic and preeruptive, requiring ingestion.

[10] Fluoride is considered essential in the development and maintenance of teeth by the American Dental Hygienists' Association.

[13] Symptoms such as fractured hips in the elderly or brittle and weak bones may be caused by fluorine deficiency in the body.

Thus, fluoride therapy results in large increases in bone mineral density but the effect on fracture rates, while positive, is small.

This practice is recommended for individuals, primarily children (who are at a greater risk of caries) in low-fluoride areas.

The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for some minerals in 1997.

Where there was not sufficient information to establish EARs and RDAs, an estimate designated Adequate Intake (AI) was used instead.

As for safety, the IOM sets Tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient.