Fluoride: Potent Cavity Fighter

The Benefits of Fluoride
By: Dr. Obikoya

Fluorine occurs naturally in the Earth's crust, water, and food as the negatively charged ion, fluoride (F-). Fluoride is considered a trace element because only small amounts are present in the body (about 2.6 grams in adults), and because the daily requirement for maintaining dental health is only a few milligrams a day. About 95% of the total body fluoride is found in bones and teeth.

Although its role in the prevention of dental caries (tooth decay) is well established, fluoride is not generally considered an essential mineral element because humans do not require it for growth or to sustain life. However, if one considers the prevention of chronic disease (dental caries), an important criterion in determining essentiality, then fluoride might well be considered an essential trace element. Having healthy gums and teeth is important, recent studies show that unhealthy gums is a predecessor to heart disease.

Fluoride comes in several forms. It is known by the following names, calcium fluoride, stannous fluoride, sodium monofluorophosphate, and sodium fluoride. Sodium fluoride is added to most public drinking water. The prime dietary source for fluoride are typically treated drinking water however, it also shoes up in foods and beverages that have been grown in areas where the drinking water has been fluoridated and then used in the manufacture of those products. Fluoride’s primary function in the human body is to strengthen the bone and it is known to prevent tooth decay. Experts contend that fluoride strengthens the teeth’s enamel by strengthening the mineral composition of the teeth themselves.

Fluoride is absorbed in the stomach and small intestine. Once in the blood stream it rapidly enters mineralized tissue (bones and developing teeth). At usual intake levels, fluoride does not accumulate in soft tissue. The predominant mineral elements in bone are crystals of calcium and phosphate, known as hydroxyapatite crystals. Fluoride's high chemical reactivity and small radius allow it to either displace the larger hydroxyl (-OH) ion in the hydroxyapatite crystal, forming fluoroapatite, or to increase crystal density by entering spaces within the hydroxyapatite crystal. Fluoroapatite hardens tooth enamel and stabilizes bone mineral.

Both calcium and magnesium form insoluble complexes with fluoride and are capable of significantly decreasing fluoride absorption when present in the same meal. However, the absorption of fluoride in the form of monofluorophosphate (unlike sodium fluoride) is unaffected by calcium. A diet low in chloride (salt) has been found to increase fluoride retention by reducing urinary excretion of fluoride.

In humans, the only clear effect of inadequate fluoride intake is an increased risk of dental caries (tooth decay) for individuals of all ages. Studies of patterns of water consumption and the prevalence of dental caries across different climates and geographic regions with different water fluoride concentrations in the United States led to the development of a recommended optimum range of fluoride concentration of 0.7-1.2 mg/liter or parts per million (ppm), with the lower concentration recommended for warmer climates where water consumption is higher, and the higher concentration for colder climates. A number of studies conducted prior to the introduction of fluoride-containing toothpastes demonstrated that the prevalence of dental caries was 40% to 60% lower in communities with optimal water fluoride concentrations than in communities with low water fluoride concentrations.

The Food and Nutrition Board (FNB) of the Institute of Medicine updated its recommendations for fluoride intake in 1997. The FNB felt there was inadequate data to set a Recommended Dietary Allowance (RDA), instead Adequate Intake (AI) levels were based on estimated intakes (0.05 mg/kg of body weight) that have been shown to reduce the occurrence of dental caries most effectively without causing the unwanted side effect of tooth enamel mottling known as dental fluorosis.

Although the role of fluoride in preventing dental caries is well established, the mechanisms for its effects are not entirely understood. Originally, it was believed that fluoride incorporated into the enamel during tooth development resulted in a more acid-resistant enamel. More recent research indicates that the primary action of fluoride occurs topically (at the surface) after the teeth erupt into the mouth.

When enamel is partially demineralized by organic acids, fluoride in the saliva can enhance the remineralization of enamel through its interactions with calcium and phosphate. In the presence of fluoride, remineralized enamel contains more fluoride and is more resistant to demineralization. In salivary concentrations associated with optimum fluoride intake, fluoride has been found to inhibit bacterial enzymes, resulting in reduced acid production by cariogenic bacteria
Fluoride intake is ideally begun early in childhood when the formation of teeth and bones is still taking place, therefore strengthening the initial buds for the future. Fluoride is also known to aid in strengthening developing bone structure. Even though it is so important to proper functioning of the human organism, fluoride deficiency does occur but typically only in regions where water that is regularly consumed is not treated with fluoridation. It is far more common to see excess intake of fluoride over deficiency.

Fluoride taking in large quantities over time slowly poisons the human body. Prolonged intake of treated water that contains more than 2 parts fluoride per million (ppm) can lead to discolored, mottled or brownish enamel on the teeth.
Extremely high concentrations, over 8 ppm can contribute to bone disorders, kidney, liver and adrenal failure as well as the heart, reproductive system and central nervous system. This is especially dangerous in young children and the elderly.

Recommended intakes of fluoride vary, however the consensus among professionals seems to be no more than 2.5 milligrams daily. Of course, before starting any form of supplementation you should consult your health care practitioner. Generally speaking, there is no reason to take individual supplements of fluoride.

References
Cerklewski FL. Fluoride bioavailability--nutritional and clinical aspects. Nutr Res. 1997;17:907-929.

Cerklewski FL. Fluoride--essential or just beneficial. Nutrition. 1998;14(5):475-476

Fabiani L, Leoni V, Vitali M. Bone-fracture incidence rate in two Italian regions with different fluoride concentration levels in drinking water. J Trace Elem Med Biol. 1999;13(4):232-237.