Fluoride has a well-established role in the prevention of dental caries through the hardening and maintenance of tooth enamel. Fluoride is also important in stabilizing the structure of bone. As fluoride is not required for growth, for reproduction, or to sustain life, it is not by definition considered an essential nutrient. However, the decline in incidence of tooth decay over the past 70 years has been largely attributed to the addition of fluoride to public water supplies.

Around the same time as other fortification initiatives in the United States, such as the iodization of salt to prevent goiter and the addition of vitamin D to milk to prevent rickets, the fluoridation of drinking water began in the 1940s to help prevent dental caries. It is estimated that 60% to 70% of the population is served by community water systems that receive fluoridated water. The Environmental Protection Agency (EPA) is responsible for safeguarding our public drinking water, which includes establishing ranges for fluoride that reduce rates of dental caries while not exceeding upper thresholds.

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In addition to fluoridated water, we obtain fluoride through fluoridated dental products, beverages made with fluoridated water, and to a lesser extent, marine fish. The AI for fluoride is set at 4 mg for men 19 years and older, and at 3 mg for women in the same age range. Inadequate fluoride, not surprisingly, results in an increased risk of dental caries. Fluoride may cause health issues if drinking water exceeds the standards set by the EPA. Tooth and skeletal fluorosis is characterized initially by small opaque flecks on the teeth and then by stains or pits in the teeth with longer-term exposure. The EPA warns that excessive intake over a lifetime may have adverse effects on bone, among them an increased likelihood of fractures because bones become brittle as they become excessively dense. The UL for men and women 19 years and older is set at 10 mg.