Fluoride is a mineral that is naturally present in the environment. It is also added as a supplement to the water supply in the United States for the purpose of preventing tooth decay.

Verywell/Emily Roberts

Updated recommendations from the U.S. Public Health Service now call for a fluoride concentration of 0.7 milligrams per liter (mg/L) in the public water supply, which is a change from the previously recommended concentration of 0.7 to 1.2 mg/L.

Health Benefits

Fluoride is added to public supplies of drinking water as well as to toothpaste and mouthwash because of its capacity for protecting against tooth decay. Tooth decay is also described as dental caries or cavities.

Fluoride supplementation has been found to prevent the process of tooth decay in infants, children, and adults. Fluoride exerts this beneficial effect on teeth through direct contact, and it also protects developing teeth that are still underneath the gums from the eventual development of cavities.

Fluoride is believed to help prevent tooth decay in two ways: preventing bacterial overgrowth and mineralizing the teeth.

Preventing Bacterial Overgrowth

Fluoride has been shown to reduce the overgrowth of certain bacteria that may play a role in causing tooth decay. Fluoride, which is an ionic element, lowers the pH level in the mouth, making the oral environment more acidic and thus less hospitable to bacteria.

Streptococcus mutans, Streptococcus sanguinis, and Porphyromonas gingivalis are three types of oral (mouth) bacteria that have been found to be inhibited by fluoride.

Mineralization of Teeth

Fluoride interacts with the teeth to form a material called fluorapatite, which mineralizes the teeth. Mineralization is a process of chemical hardening, an effect that prevents tooth demineralization (breakdown). Interestingly, while fluorapatite is not a natural component of teeth, it is beneficial and has not been found to cause any harm to teeth.

The fluorapatite mineralization caused by fluoride supplementation also helps the teeth resist damage that can be caused by food, drinks, and bacteria.

In terms of human health and nutrition, fluoride is a trace element, which comprises a relatively small percentage of the body’s composition.

It is believed that fluoride, while beneficial for improving community health and quality of life, may not be necessary for survival.

Possible Side Effects

Fluoride intake is not recommended at levels higher than 10 mg per day. Excess fluoride can produce varying effects depending on the amount of fluoride exposure and whether it occurs chronically, over a long period of time, or acutely (rapidly).

Chronically high levels of fluoride intake can affect teeth and bones, while acute ingestion of large amounts of fluoride can cause more dangerous side effects, and may even be life-threatening.

Chronic Over-Exposure to Fluoride

Dental fluorosis is the most well-documented side effect of excess fluoride. There is also some evidence that excess fluoride ingestion may increase the risk of developing osteoporosis and having bone fractures.

Fluorosis

Fluorosis can begin at any age, and it manifests with white spots or white streaks on the teeth. Because fluoride-induced mineralization can even affect teeth that are still developing underneath the gums, fluorosis can affect children who are exposed to high levels of fluoride while their teeth are still developing. Sometimes, fluorosis may produce a rough texture on the surface of the teeth.

Fluorosis is mainly a cosmetic concern and is not believed to be harmful to teeth. Fluorosis does not improve on its own, and it is very difficult to repair. If you develop this condition, be cautious of at-home cosmetic treatments, such as tooth whitening gels or creams, because they can cause further discoloration of your teeth.

To avoid fluorosis, do not expose your teeth to excess fluoride, either with supplements or through excessive exposure to toothpaste or mouthwash.

Brush your teeth no more than three times per day, don’t use mouthwash more than a few times per day, and be sure to spit out mouthwash from your mouth within 30 seconds.

Bone Fragility

Excessive fluoride ingestion has also been found to cause a rare condition called skeletal fluorosis, which is characterized by fragile bones and hardening or stiffness of the joints. Skeletal fluorosis can increase the risk of bone fractures.

Acute Fluoride Toxicity

Acute fluoride toxicity can cause stomach upset, nausea, vomiting, and diarrhea. In some cases, especially with young children, the effects can become life-threatening.

Acute toxicity is uncommon because the concentrations of fluoride in water, toothpaste, and mouthwash are too low to cause an overdose of fluoride. While it is rare, a person can consume dangerous amounts of fluoride accidentally through industrial chemicals.

Dosage and Preparation

The recommended daily intake of fluoride depends on age.

0.7 mg daily for toddlers

3 mg daily for adult women

4 mg daily for adult men

What to Look For

In addition to supplemented sources of fluoride, the mineral is also found in food. Foods that contain fluoride include seafood, raisins, and potatoes. It is also present in drinks such as tea, wine, and grape juice. The amount of fluoride in these products is less than one-hundredth of a gram, which is too low to have a protective or an adverse effect.

Fluoride Supplements

If you or your child cannot consume water that comes from the regular public water supply, you may not be getting the protection against tooth decay that fluoride can provide. You can use over-the-counter fluoride-containing toothpaste and mouthwash to obtain fluoride protection against tooth decay.

In addition, according to the American Dental Association's recommendations, your doctor or dentist can prescribe oral (to take by mouth) or topical (to put directly on your teeth) fluoride. You can also have fluoride professionally applied to your teeth. Your health care professional will be able to advise you if these steps are necessary.

Alternative Fluoride Supplementation

In communities where it is hard to supplement the water supply with adequate fluoride, the mineral can be added to milk or salt. These methods are considered safe, and they have been shown to be effective in reducing the incidence of dental caries in many countries.

Other Questions

What are other side effects of chronic fluoride exposure?

There have long been concerns that the side effects of chronic fluoride exposure include the possibility of fluoride-induced thyroid disease, learning disabilities, autism, blood disorders, and osteoporosis. These concerns, however, have not been validated by scientific studies.

Is fluoride approved as a safe supplementation?

At the current time, the U.S. Public Health Organization and the American Dental Association consider fluoride supplementation to be safe and beneficial.

A Word From Verywell

Fluoride supplementation of the water supply is considered among the most cost-effective advances in public health. While fluoride has been found to reduce the incidence and severity of dental caries, it is not beneficial in excess amounts. If you do not have access to fluoride supplementation, or if you cannot take it for any reason, you should rest assured that while you may miss out on its protective effects, there is no serious consequence to lack of fluoride aside from losing its protective benefits for the teeth. You'll need to be extra careful about keeping up with dental hygiene at home and making sure you have regular check-ups at your dentist's office.