Fluoride is a trace mineral. It is present in the body in a very small amount. Most fluoride in the body is found in the bones and teeth.
Fluoridated water is the primary source of fluoride. The fluoride content of food depends upon the fluoride content of the soil in which the food was grown. Some infant formulas that are made or mixed with fluoridated water also contain fluoride. Brewed tea can contain significant amounts of fluoride. The amount depends on the amount of tea used, the water fluoridation concentration, and the brewing time. Fish with edible bones, such as canned salmon, also provides some dietary fluoride. Fluoride mouth rinses and toothpastes are sources of fluoride to the outside of the teeth (topical fluoride).
Although fluoride helps harden the tooth enamel during the time teeth are developing, the main action of fluoride occurs after the teeth have erupted. Water fluoridation has been found to be effective in preventing dental decay in both children and adults. Topical fluoride is important in preventing tooth decay in already erupted teeth. It does this by helping to prevent the destruction of the tooth enamel by acid in the mouth. It also interferes with the formation of dental plaque.
Fluoride that is eaten is secreted in the saliva and can protect teeth in the same way as topical fluoride. Fluoride supplementation can promote bone building, but early studies in people with osteoporosis have found that the structure of the new bone was abnormal. It was weaker than normal bone and possibly more prone to fracture. Gastrointestinal side effects were also a problem. Researchers are working to find a formulation and dosage regimen that will result in building normal bone.
Although there is no recommended dietary allowance, the Food and Nutrition Board of the National Academy of Sciences has established an adequate intake (AI) for fluoride: infants ages 0 through 6 months = 0.01mg/dayinfants>age 6 months = 0.05 mg/dayinfants ages 7 to 12 months = 0.5 mg/dayages 1 to 3 years = 0.7 mg/dayages 4 to 8 years = 1 mg/dayages 9 to 13 years = 2 mg/dayages 14 to 18 years = 3 mg/daymales age 19 years or older = 4 mg/dayfemales age 19 years or older = 3 mg/day
The American Dental Association Council on Scientific Affairs recommends fluoride supplements beginning at 6 months and continuing until age 16 for children who live in areas where the water does not contain fluoride.
However, because foods processed with fluoridated water can contain significant amounts of fluoride, all sources of fluoride in a child's diet should be identified before beginning fluoride supplementation.
Some people have concerns about the safety of fluoridated water. Fluoride has been studied for many years. The levels used in fluoridated water pose no danger of harmful effects to health and help to greatly reduce the risk of tooth decay and other periodontal diseases.
Extensive research has proven that communities with fluoridation of drinking water at a level of 1 part per million do not have higher rates of cancer, heart disease, Alzheimer's disease, Down syndrome, or liver disease.
Still, about 46% of public water supplies are still not fluoridated. The amount of fluoride in well water can vary greatly. Well water should be tested to determine the amount of fluoride it contains.
Home water filters may remove a significant amount of fluoride from water. However, water softeners do not seem to change fluoride levels.
Too much fluoride can cause mottled teeth or dental fluorosis. Fluorosis can range from very mild to severe. Mild fluorosis causes chalky white spots or patches on the teeth. These teeth are highly resistant to cavities.
Severe fluorosis causes the teeth to have brownish stains. The teeth are healthy, but they are stained. Fluorosis usually affects people who drink well water that naturally contains high levels of fluoride.
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Duyff, R., MS, RD, CFCS. (1996). The American Dietetic Association's Complete Food&Nutrition Guide. Minnesota: Chronimed Publishing.
Murray, M., ND. (1996). Encyclopedia of Nutritional Supplements. California: Prima Publishing.