Though fluorine as fluoride has been shown to reduce dental cavities when added to toothpaste or drinking water, there is still some question as to whether it is an essential element. In other words, if we do not have fluoride, will we develop any problems? It is my feeling that eating a natural diet low in refined flours and sugars along with some basic oral hygiene will maintain healthy teeth and gums.
Fluorine itself is a poisonous gas, as are the related elements chlorine and bromine. Fluorine, as fluoride, is found in the earth’s crust in combination with other minerals, and is also part of seawater. Fluoride is available naturally in the diet as calcium and sodium fluoride. It is sodium fluoride that is added to the drinking water of many cities to help reduce dental caries. There is some controversy as to whether fluoridation has some subtle poisoning effect or whether it is nontoxic and beneficial. In my opinion, fluoridated water is another example of technology’s treating the effect instead of correcting the cause, which is primarily poor diet.
Fluoride is probably not essential to humans, though it is helpful in strengthening the bones and teeth. It is found only in trace amounts, about 2-3 grams, in the body, and most of that is in bones and teeth. The blood level of fluoride is about 0.3 mg. per 100 ml. Fluoride has no known function other than strengthening teeth and bones.
Intestinal absorption of fluoride, especially the more soluble sodium fluoride, is fairly good. Calcium, aluminum, and perhaps other minerals may interfere somewhat with absorption by making less soluble fluoride salts. About half of ingested fluoride, about 3 mg. per day, is eliminated through the kidneys and a little more through perspiration. The remainder is stored mainly in the bones.
Sources: Natural fluoride is present in the ocean as sodium fluoride, so most seafood contains some. People who eat large quantities of fish, such as the cultures of the Caribbean, have been shown to have stronger teeth and less incidence of dental cavities, the most common disease worldwide, than do others. This may also be related to other factors. Gelatin and tea also contain fluoride. In fact, a study showed that school children in England were obtaining over 1 mg. of fluoride daily from tea alone (that is black tea, with caffeinelike molecules theophylline or theobromine plus tannic acid, not herbal teas). Most plant-source foods contain some fluoride, though the amount can vary greatly depending on soil fluoride content. Soil deficiency of fluoride is fairly common.
Fluoride is added to the drinking water of many municipalities at the concentration of 1 ppm. More than 2 ppm can cause problems, so the concentration must be finely monitored. People drinking city water who also consume fluoride-containing foods or black teas can develop fluoride problems as well, though toxicity has not been found to be appreciable with moderate amounts.
Stannous (tin) fluoride was originally used in toothpaste for protection against tooth decay. But it has been found that fluoride is more effective in this area when provided internally by drinking water than when it is applied locally, and we probably do not want too much extra tin anyway (though tin may be an essential mineral in trace amounts as well). Overall, I do not advocate drinking fluoridated water-or any city water, for that matter (see Chapter 1, Water). It is better, I believe, to drink filtered water to be safe from chemical and toxic metal pollutants and to eat a more natural diet with some seafood, which is also thought to protect against atherosclerosis and heart disease as well as keep the teeth healthy.
Functions: Studies show that fluoride helps strengthen the crystalline structure of bones and teeth. The calcium fluoride salt forms a fluorapatite matrix, which is stronger and less soluble than other calcium salts and therefore is not as easily reabsorbed into circulation to supply calcium needs. In teeth, this fluoride salt reduces the potential for breakdown from acids in the mouth or from demineralization, minimizing tooth decay. In bones, fluoride reduces loss of calcium and thereby may reduce osteoporosis. No other functions of fluoride are presently known, though it has been suggested to have a role in growth, in iron absorption, and in the production of red blood cells. This needs further research.
Uses: Fluoride’s main use is as an additive to drinking water as well as toothpaste and mouthwash for the prevention of tooth decay. When added to water at 1 ppm, it can reduce dental caries by 30-50 percent. Fluoridated water works best, however, when its use is begun in infancy or early childhood and continued throughout childhood. Fluoride-treated water does not decrease the gum disease that may also result from poor nutrition and poor hygiene. As is typical of Western medical thinking, we treat the result as if it were the problem itself, rather than correcting the cause-the overuse of sugar and poor dietary habits in general-which may be causing decay even deeper in the body, a process that may take us many more years to discover. I wonder what new xenon-coated bandage will be invented to patch that up.
On a more positive note, the use of sodium fluoride has been shown to be helpful in the treatment and possibly the prevention of osteoporosis, though the results from various studies are mixed. Epidemiologically, the incidence of osteoporosis is slightly reduced in fluoridated-water users. In older studies, bone density, as well as blood pressure, was improved by treatment with 50 mg. of sodium fluoride (NaF) and 900 mg. of calcium daily and 50,000 IUs of vitamin D twice weekly. There is concern, however, that fluoride-treated bones will not give up calcium easily to the body when needed, which may contribute to calcium deficiency. It is obviously much better to prevent osteoporosis by eating calcium-rich foods; supplementing calcium, magnesium, and vitamin D; maintaining overall mineral balance; eating a healthy diet; and exercising regularly.
There is some preliminary research evidence that fluoride may help in treating otosclerosis, a loss of hearing due to deposits in the ear. Hearing loss in later years, when it is due to osteoporosis, or loss of minerals from the tiny ear bones, may be reduced with fluoride treatment as well.
Fluoride is not generally used as a supplement in multivitamin/mineral formulas. It is added to some infants’ and young children’s vitamins to aid in the prevention of tooth decay. As sodium fluoride, it is occasionally prescribed medically in the prevention or treatment of dental disease.
Deficiency and toxicity: Toxicity from fluoride is definitely a potential problem. As stated, fluoridated water must be closely monitored to keep the concentration at about 1 ppm to effectively reduce dental decay without producing side effects. At concentrations greater than 2 ppm, fluoride can cause mottling, discoloration, and pitting of the teeth, though it will still maintain tooth strength and prevent cavities. At 8 to about 20 ppm, initial tissue sclerosis will occur, especially in the bones and joints, which can cause arthritic symptoms. At over 20 ppm, much damage can occur, including decreased growth and cellular changes, especially in the metabolically active organs such as the liver, kidneys, adrenal glands, and reproductive organs. More than 50 ppm of fluoride intake can be fatal. In terms of total fluoride intake, around 20 mg. per day will usually cause some tooth discoloration and bone problems. Animals eating extra fluoride in grains, vegetables, or in water have been shown to have tooth and bone lesions. Fat and carbohydrate metabolism has also been affected. There are many other concerns about fluoride toxicity, including bone malformations and cancer.
Sodium fluoride is less toxic than most other fluoride salts. In cases of toxicity, extra calcium will bind with the fluoride, making a less soluble and less active compound.
Fluoride deficiency is less of a concern. Low fluoride or lack of fluoride use does correlate with a higher number of dental caries, given a less stability and strength of the bones and teeth in general. It is possible, that traces of fluoride are essential, but it is not clear whether it is a natural component of our body tissues. Low fluoride levels may correlate with a higher amount of bone fractures in the elderly, but that is usually in the presence of osteoporosis.
Requirements: There is no specific RDA for fluoride. Nor is it mandatory to add fluoride to the water. Many cities do not follow this much-supported preventive measure. On a worldwide level, there has been a lot of disappointment with the use of fluoridated water. People who drink fluoridated city water get about 1 mg. per day from it. Research shows that the amount in the average diet varies widely, depending on choices of foods and water use. Nonfluoridated water users take in between .35 mg. and 1.5 mg. per day, while the average city diet with fluoridated water contains about 2-3 mg. The suggested safe intake of fluoride (not necessarily the optimum, which we really do not know) is between 1.5 and 4.0 mg. per day. Amounts up to 15-20 mg. per day are probably well tolerated, though we do not know the long-range effects. And until we do, I personally would discourage overuse of fluoride. A complete review of the fluoride controversy, written from a global viewpoint, appeared in the August 1988 issue of Chemical Engineering.