Food Sources High In Fluoride

Overview

Fluoride is a mineral that is known to help prevent dental cavities (tooth decay).¹ It is naturally present in water and some foods in trace amounts, as well as being an ingredient in toothpaste and in many mouth rinses.¹ 

It has been seventy years since it was discovered that fluoride helps prevent tooth decay and the American Centers for Disease Control and Prevention (CDC) has even classified fluoridation of water (the addition of fluoride to tap water) as one of the ten greatest public health achievements of the 20th century.⁴ 

But how do you know if you are ingesting the recommended dosage of fluoride? Where can you even find natural food sources of fluoride to include it in your diet? In this article let’s answer these questions to help understand a bit more about fluoride, what food sources contain fluoride,  and how it can help improve your health.

What is fluoride?

Fluoride is a mineral and is the ionised form of the gas fluorine, a chemical element.¹ The term “chemical element” might seem scary to some, as it may invoke the idea that fluoride is an artificial industrial product. However, that couldn’t be further from the truth, because it is a naturally occurring mineral, present in water and many foods in small concentrations. 

Think of chemical elements as building blocks–combining a number of different elements with each other or with themselves creates different chemical molecules, just like combining pieces of Lego can produce an infinite number of creations, from houses to animals to everything else; everything we touch and see is made out of chemicals in different combinations.² Water, for example, is also a chemical, its chemical formula being H₂O - two atoms of the element hydrogen and one atom of the element oxygen.²

The periodic table is a way of organising all the known chemical elements according to their reactive properties and internal structure. Each element has its own symbol. Fluorine is the element symbolised as “F” that can be found in group 17, period 2 of the periodic table. 

The element fluorine tends to attract an electron (a negatively charged particle) to stabilise itself and when it does so, it transforms itself into fluoride, a negatively charged ion symbolised as “F ”.³ This negative fluoride ion is usually combined with sodium to make sodium fluoride (NaF), which is the fluorine salt most commonly used to fluoridate water.³

The importance of fluoride for health

Fluoride is known to help strengthen the enamel of the teeth.¹ But how exactly does it do it?

Human teeth are composed of a mixture of hard tissue and soft tissue– the soft tissue is the pulp, the innermost layer that is protected by two hard, mineralized tissues, the dentine and the enamel.⁵ These hard outer layers are made out of minerals like hydroxyapatite, forming a very hard and dense tissue.⁵ 

When we consume sugars, the bacteria in our mouths (mostly Streptococcus mutans, Streptococcus sobrinus, and lactobacilli) take these sugars and ferment them to transform them into energy for their own functions.

This fermentation causes a rise in the acidity level (drop in the pH level) in the mouth and this acid environment will dissolve the hard mineral component of the enamel and dentine, causing holes in the teeth to form known as cavities.⁶ 

Through the cavities, bacteria can then penetrate the underlying dentine and infect the pulp tissue, leading to a loss of tooth structure and pain as nerves are irritated. If left untreated, dental decay can lead to incapacitating pain, death of the pulp tissue and tooth, tooth extraction and loss of overall dental function, and may progress to an acute systemic infection. 

Certain factors need to be present for tooth decay to occur:

• Tooth surface: as obvious as it is, an individual cannot have cavities if they don’t have teeth or exposed dental tissue, as a tooth that is retained inside the bone is protected from cavities⁶
• Poor oral hygiene: this leads to a higher concentration of bacteria and their formation of a biofilm (dental plaque).The dental plaque flets the bacteria inside the film ferment sugars freely, by protecting them from the antibacterial and antacid saliva
• Sugar intake: bacteria need carbohydrates (sugars) like sucrose, fructose and glucose to produce energy for their own metabolism by fermentation. In the process these sugars are transformed into acid by the bacteria, and the acid will slowly degrade the dental tissue⁶
• Time: this is a crucial factor in the development of dental cavities; time will allow bacteria to form the dental plaque and to ferment sugars into acid⁶

But how does fluoride contribute to preventing dental decay? 

Fluoride binds itself to the hydroxyapatite crystals, making them stronger. These fortified crystals of fluorapatite are less likely to be demineralized (that is, to be dissolved) in acid conditions. Also, because bound fluoride helps attract additional calcium, it also helps remineralize small, incipient cavities just starting to form.⁶ 

This is why fluoride is often used topically, in the form of toothpaste or mouthwashes for daily use at home or as a fluoride varnish to be applied by your dentist.⁷

Besides helping prevent tooth decay (regardless of age), fluoride is also considered essential for bone growth in kids, as it stimulates the proliferation of osteoblasts (bone-building cells), according to Harvard University.⁸ Although not classified as an essential nutrient, lack of fluoride can cause dental and potentially bone problems.⁸

Natural food sources of fluoride

As fluoride is a mineral present in soil, most plants absorb it during their growth and development. Of all food sources, black tea has been found to contain the largest amount of fluoride.¹ The table below shows a few other foods and beverages that contain fluoride.¹

*The total amount of fluoride can vary depending on the level of fluoride in the water used to prepare these foods and drinks

Other foods rich in fluoride are meats like lamb, tuna and chicken, as well as milk and cheese.¹ For vegetarians and vegans, fruits like apples, raisins and grapefruit, and vegetables like corn and asparagus are good sources of fluoride intake.¹

Fluoride supplementation and fortification

Fluoridation of water is a public health measure used worldwide and has been implemented in the United Kingdom in many areas of the West Midlands, the North East, the East Midlands, Eastern England, the North West, Yorkshire and Humber.⁷ In these areas of low natural fluoride, fluoride is added to the water to bring the level up to around 1mg per litre. You should contact your local water supplier if you want to know if the water you drink is fluoridated.⁷

If your water is not fluoridated, you should talk to your dentist as you may need to develop strategies to increase your fluoride intake, either through your diet or through use of topically applied products. When it comes to infants and children up to 8 years old, the maximum recommended daily dose of fluoride is 0.10 mg/kg, while for older children and adults (who are no longer at risk of developing fluorosis) is 10mg/kg every day, though the European Union does not recommend consumption of more than 7mg/kg of fluoride a day.⁹

The concentration of fluoride in product sources varies greatly:

• Water: fluoridated water in the United Kingdom varies locally and can reach up to 1mg per litre⁷
• Toothpaste: the most effective toothpastes when it comes to prevention of dental cavities contain between 1350 and 1500 ppm (particles per million) of fluoride for adults and older children; the actual amount of toothpaste that should be used varies with age.⁷ This amounts to approximately 1.3 mg of fluoride per brushing¹
  • Children under 3 years old should brush their teeth twice a day with a smear of toothpaste containing a minimum of 1000 ppm of fluoride⁷
  • Children between the ages of 3 and 6 years old should brush their teeth at least twice a day with a pea-sized amount of toothpaste containing at least 1000 ppm of fluoride⁷
  • Older children and adults should brush their teeth at least twice a day with a toothpaste containing 1350-1500 ppm of fluoride⁷
• Mouthwashes: can be prescribed by a dentist if there are cavities present, as they will help remineralize the enamel, with varying concentrations of fluoride⁷
• Fluoride gels and varnishes: these are used by dentists, applied locally and periodically to your teeth, and can contain from 1.3 to 31.2 mg of fluoride¹
• Dietary supplements: some dietary supplements or multivitamins contain sodium fluoride with concentrations that vary from 0.25 mg to up to 1mg¹

Risks of fluoride intake

Fluoride is safe to consume, provides multiple health benefits when used within reasonable consumption limits, and there is no evidence of serious diseases being caused by normal fluoride consumption.⁷

The biggest risk from overconsumption of fluoride is in children, and it’s called fluorosis.⁷ Fluorosis is the accumulation of fluoride in the teeth while the enamel is still forming, causing fine white lines or speckles to appear all over the enamel with mild, or darker, brownish discolouration to appear in severe cases of fluorosis.⁷ It is, however, very uncommon to see fluorosis because the amount of fluoride in water is carefully regulated by the Drinking Water Inspectorate (DWI), and the trace amounts found in foods and drinks are not enough to have a significant impact.⁷

Consumption of high doses of fluoride can happen accidentally (through excessive supplementation or ingestion of dental-grade topical products) and can result in acute poisoning: presenting with with symptoms like nausea and vomiting, abdominal pain, diarrhoea, and periostitis (inflammation of the membrane that envelops and protects the bones), and death is possible, though very rare.¹

Another cause of high fluoride consumption is medication. Voriconazole is an antifungal medication that can be used to treat severe fungal infections and daily doses contain 65 mg of fluoride. Prolonged use (greater than 4 months) can cause a high systemic concentration of fluoride with negative health impacts.¹ This can lead to skeletal fluorosis and periostitis.¹

Overall, fluoride poisoning is rare and easily preventable through rational consumption of fluoride, and the benefits of consuming fluoride far outweigh the risks associated with it.

Summary

Fluoride is a naturally occurring chemical that helps prevent tooth decay and can help bone growth in children. It can be found in water naturally, but also through public healthcare fluoridation policies that date back to the 20th century, and in many foods like tea, coffee, seafood, meat and milk. Other sources of fluoride consumption are toothpaste, mouthwashes and fluoride gels and varnishes that a dentist applies. Although overconsumption can lead to negative side effects like fluorosis, fluoride poisoning is very rare and easily preventable, and the positive impact on dental health is so significant that maintaining adequate fluoride intake is an important matter.