When you think of fluoride, you probably think of the controversial ingredient in toothpaste or drinking water.
But it can actually be present in food as well, and adequate intake can help with more than just your dental health.
In its natural state, fluoride is a mineral that is the ionic form of the element fluorine, which is commonly found in soil and rocks. From there, it leaches into groundwater.
Perhaps you’ve heard conspiracy theories or cautionary tales from medical professionals who aren’t too fond of this omnipresent compound. While most of us know that fluoride is found in everyday necessities like water and toothpaste, did you also know that it’s present in some of your favorite foods?
Whether you’re looking to increase or avoid fluoride intake, it’s important to know where this mineral is most abundant. So, what is the most reliable source of dietary fluoride? We spoke to several experts to find out the answer.
Water and Dental Products: The Most Common Sources of Fluoride
In the U.S., water has been fluoridated for over 70 years, making it the most common source of intake. Most community water systems contain 0.7 mg of fluoride content per mL of water, which is the U.S. Public Health Service’s recommendation.
“This amount is enough to reduce tooth decay by 25% and has been shown to be otherwise harmless,” said Daniel Balaze, a dentist practicing in Southern California. If you’re not sure how much fluoride is in your water, there are home tests you can buy to find out for yourself.
Although the practice of fluoridation still continues to this day, many scientists have questioned the efficacy and safety of adding this mineral to local water supplies. In June 2015, an independent network of researchers and health care experts, known as the Cochrane collaboration, released an analysis of 20 studies focused on water fluoridation.
While the research group did confirm that it was effective at reducing tooth decay in children, there was no study that demonstrated the same benefit for adults. Furthermore, the Cochrane report also that early scientific studies were flawed because they didn’t account for other sources.
Fluoride is also commonly found in most toothpaste and mouthwash products, and that ubiquity alone is usually enough to meet an adult’s recommended fluoride intake.
“While fluoride is added to toothpaste and government-regulated water, not most bottled water, dietary sources can help to fill the gaps where these sources are lacking,” said Lisa Richards, a nutritionist and author of “The Candida Diet.” “Many people choose not to drink water or use toothpaste that has been fluoridated for personal reasons, but fluoride is still necessary and beneficial to bone health.”
A Part of Daily Nutrition: Dietary Fluoride in Food Sources
Despite the fact that fluoride is present in our hygienic products and tap water, this substance can also be found in our food as well.
One food that often contains fluoride is fish that come in cans, such as sardines, tuna, and salmon. “Fish from freshwater have higher rates of fluoride in their bones and skin,” Richards said.
Roughly 95% of body fluoride is found in bones and teeth. Products that contain mechanically separated meat — like chicken fingers, nuggets and sausages — often have fluoride because bone particles remain the deboning process, said nutrition and wellness coach Monica Ruiz-Noriega, Ph.D. This dynamic is also why fish with bones, such as sardines, can be a good source of this mineral.
Shrimp may also contain fluoride that builds up in their shells and muscles.
“Even if they’re transferred into new water with less fluoride in it, they don’t release the fluoride already built up in their system,” said Samantha Radford, Ph.D., an environmental chemist and public health expert. “So if there’s a lot of fluoride in the water the shrimp live in, they will have a high fluoride content.”
Grapes and raisins may provide fluoride as well because they’re often grown using a pesticide called cryolite. You can also find it in teas, particularly black teas, tea infusions, and older teas. In addition, tea picks up fluoride from the water it’s steeped in. This effect might also make drinking certain teas slightly riskier.
According to Ruiz-Noriega, when fluoride-rich foods are ingested, they typically don’t provide enough fluoride to make a major difference, but that deficiency isn’t usually a problem because other sources are so widely available. These foods are also more likely than fluoridated water to contain levels that are deemed safe.
In rare cases, people will receive fluoride prescriptions from their dentist. Usually, fluoride supplements are necessary when someone has an acidic mouth that can lead to lots of cavities or cavity-causing bacteria. If someone has a fluoride deficiency, for example, these acids could build up and cause tooth decay.
“This means the teeth are relatively demineralized and need to be strengthened,” Balaze explained. “The fluoride and the phosphates fill in and strengthen any areas that are weakened by acids. They will not fix or repair cavities that have gotten past a certain size, however.”
People tend to be at high risk for cavities if they’ve had a cavity in the past three years, so fluoride is sometimes prescribed within those three years as a preventative measure.
Prescription fluoride can be given in three forms: tablets (which are usually only necessary for children in places without fluoridated water), prescription-strength toothpaste (which is used for people at high risk for cavities), and prescription mouth rinses or gels.
The Purported Health Benefits of Fluoride
Our tooth enamel is made of a chemical called hydroxyapatite, which can wear away when exposed to acidic substances like orange juice or soda. According to Balaze, this degradation leaves the teeth more porous and prone to cavity formation.
“When we expose that now-demineralized enamel to fluoride, the fluoride moves in and forms fluorapatite, a much stronger and more cavity-resistant form of enamel,” he told Public Goods.
“When fluoride is present in the proper concentrations in the diets of children, this cavity-resistant enamel is produced during the development of the teeth instead of hydroxyapatite.”
Because of this theory, many dentists and researchers believe that the intake of fluoride is most important for children. Some studies show it can decrease your risk of cavities by about 25%.
Fluoride can help with bone health in general, beyond the teeth, Richards said.
“Fluoride stimulates the growth of cells that build bone,” she told Public Goods. “Fluoride in small amounts can be beneficial and enhance bone growth and strength.”
Everyone has different fluoride needs depending on their medical history and medications, as well as how prone they are to cavities, so should ask your dentist to know exactly how much you need.
Is Fluoride Safe?
Some research has suggested that fluoride could be neurotoxic, Radford Said. One 2019 study published in JAMA Pediatrics, for example, found that fluoride consumption among pregnant women was associated with lower IQ in children.
“There are many ways fluoride can interact with the brain and nervous system to cause reduced IQ, memory, and capacity to learn,” said Radford, who believes there is no need for dietary fluoride.
This argument was behind the U.S. Public Health Service’s decision to lower the recommended fluoride concentration in water by almost half in 2015.
There have also been studies linking excessive fluoride to cancer, hormonal issues, weakened bones, thyroid problems, and a dental disease called fluorosis. One 2005 study concluded that high numbers of children were at risk for fluorosis due to high amounts of fluoride in water, as well as food and beverages. Some activists are calling on the U.S. government to stop the fluoridation of water.
Still, Balaze said most research suggests that fluoride is generally safe.
Richards agrees with this sentiment.
“Some consumers may be concerned that their overall exposure to fluoride (across toothpaste, drinking water, and foods) may be too high,” she said. “There is some limited evidence linking fluoride exposure to impaired brain development and other conditions. However, this is more of a problem in countries like China and India, where fluoride levels are naturally very high in drinking water.”
Does Dietary Fluoride Need to Be Part of Daily Nutrition?
No, in most cases, you shouldn’t need to worry about increasing fluoride intake through food and prescription-grade products. In short, as long as your drinking water and/or using a toothpaste that has fluoride in it, which is usually the case, you don’t need to intentionally add more to your dietary plan.
However, if this is not the case, or if you are particularly cavity-prone, it may be a good idea to increase your intake of fluoride-rich foods, such as fish and older black teas. Certain dental conditions or deficiencies may require you to take prescription fluoride, so talk to your dentist about your options.
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