What Is Fluoride & Is It Safe?

The use of fluoride in drinking water and toothpaste is a controversial topic. Both proponents and opponents of fluoride have scientific evidence to support their positions.

As with most controversial issues, the truth is somewhere in the middle. There are both tangible benefits and notable risks to fluoride use. The right amount can strengthen teeth and prevent tooth decay, but higher doses can be harmful.

Why are Most Dentists Pro-Fluoride?

Dentists tend to be in favor of fluoride because, simply put, it makes teeth stronger. When you drink fluoridated water or brush your teeth with fluoride toothpaste, the fluoride is incorporated into your tooth enamel.

The bacteria that cause tooth decay secrete acids that break down enamel. Acidic foods and drinks can also wear away enamel. In addition to making your teeth more vulnerable to dental caries (cavities), thin enamel can also make your teeth more sensitive.

When your tooth enamel is infused with fluoride, it’s harder for acids to break your enamel down. This means fluoride in the right doses makes your teeth less likely to develop cavities and less sensitive.

According to the U.S. Centers for Disease Control and Prevention, community water fluoridation reduces the risk of cavities by about 25%.¹ It allows children who don’t receive quality dental care to get the benefits of topical fluoride.

Why are Some People Anti-Fluoride?

While low doses of fluoride can benefit your teeth, high doses can cause serious health problems. Some people, including researchers and dentists, argue that community water fluoridation isn’t worth the risk.

Besides the potential for poisoning in high doses, specific points raised by opponents of fluoridation include:

• Different people need different amounts of water; athletes, pregnant women, and others will get a higher dose of fluoride than needed.²
• Many countries don’t add fluoride to the public water supply but have still seen a decline in tooth decay due to improved dental care.³
• When treating dental fluorosis is accounted for, community water fluoridation may not be more cost-effective than dental care.⁴

In addition, the benefits of fluoride are primarily topical, as they’re due to fluoride making contact with your teeth, not due to it entering your body. There also doesn’t seem to be any additional benefit to fluoridated water if you’re already using fluoride toothpaste.^{2, 5}

What Is Fluoride?

Fluoride is a naturally occurring mineral that can be found throughout the world in lakes, rivers, and groundwater. It’s also present in all plant life since it’s absorbed from the surrounding water and soil.

While fluoride is best known as an important part of modern dentistry, it also has a variety of industrial uses, including aluminum production and biochemical testing.

How Are We Exposed to Fluoride?

Fluoride is very prevalent in nature, so virtually everyone consumes at least trace amounts through food and water. Some food and drink items, such as red wine, tea, and raisins, contain significant amounts of fluoride (even more than fluoridated water).

But when discussing the risks and benefits of fluoride, we must distinguish between two types of fluoride exposure⁠—systemic and topical.

Systemic Fluoride Exposure

Systemic fluoride means fluoride that’s been ingested and absorbed by your body. In addition to the (usually) small amounts of fluoride you get from food, the public water supply in many parts of the world has fluoride added.

Fluoride isn’t a nutrient, so the benefit of consuming it is simply that it comes into contact with your teeth. It does this when you first consume it and after your body clears it. Most of the fluoride in your body ends up in your teeth and bones.

There isn’t any benefit to fluoride coming into contact with your organs and bodily tissues (aside from your teeth and bones), but it’s also unlikely to cause harm at low levels.

Topical Fluoride Exposure

Topical fluoride refers to fluoride that makes contact with your teeth. It combines with the minerals in your tooth enamel, making it more decay-resistant.

Fluoride comes into contact with your teeth in a few ways. These include:

• As an ingredient in toothpaste
• As a fluoride polish during a professional dental cleaning
• Through food and water before being ingested
• Through your teeth and bones after circulating in your bloodstream

Excessive topical fluoride can cause dental fluorosis, discoloring your teeth and potentially making them more brittle. However, even people with fluorosis are at lower risk of tooth decay.

What are Some Risks of Fluoride?

A high enough dose of fluoride can lead to acute fluoride poisoning.⁶ This condition is potentially lethal, especially for a small child.

Symptoms of fluoride poisoning include:

• Nausea
• Vomiting
• Diarrhea 

Exposure to excessive fluoride over a long time, even if it never causes acute poisoning, can also cause lifelong health issues such as:

• Dental fluorosis
• Skeletal fluorosis (leading to arthritis and possibly bone fractures)
• Kidney and thyroid problems

Some studies have also suggested that excessive fluoride intake during childhood could result in abnormal brain development. More research is needed to confirm this.^{7, 8}

Why Avoid Fluoride in Toothpaste?

While fluoride toothpaste is much less controversial than fluoridated water, some people prefer to avoid it. Two main possible reasons make it worthwhile to opt for toothpaste without fluoride:

• You have small children — Babies and toddlers are more likely to swallow toothpaste. If the toothpaste contains fluoride, this could put them at risk for fluoride poisoning.
• You’re using toothpaste with hydroxyapatite instead — Hydroxyapatite is a form of calcium phosphate that makes up most of your tooth enamel. Toothpaste made with hydroxyapatite has similar remineralizing benefits to those made with fluoride.^{9, 10}

For these reasons, our top recommendation for kids’ toothpaste is Kinder Karex, which uses hydroxyapatite as an alternative to fluoride.

However, for most adults, toothpaste with fluoride or hydroxyapatite has no harm (and plenty of benefits). Both compounds are incorporated into your enamel, making it stronger and more resistant to tooth decay.

What is the Safest Way to Use Fluoride?

The safest form of fluoride exposure is topical (directly on your teeth) and in moderate doses. Brushing with fluoride toothpaste and having fluoride applied to your teeth twice a year by the dentist are not likely to put you in danger of excess fluoride exposure.

Even when fluoridated water is added to the picture, the amount of fluoride you’re exposed to is unlikely to pose a risk. However, there are some situations where you may get too much or too little fluoride.

Too Much Fluoride Exposure

The most common way to be exposed to too much fluoride is to drink water from a naturally high-fluoride source. In some parts of the world, groundwater contains dangerously high fluoride levels. If you live in such an area and get water from a well, your health may be at risk.

Fluoride is added to water in many places, but some countries (Estonia, for example) defluoridate the public water supply. They reduce the amount of fluoride to optimal levels (good for oral health but not likely to cause fluorosis).¹¹

Other ways you might be exposed to excess fluoride include:

• Regularly using professional-strength fluoride products — If you routinely purchase high-fluoride dental products without consulting your dentist, you may be at risk of overexposure.
• Swallowing fluoride toothpaste instead of spitting it out — Fluoride toothpaste isn’t meant to be swallowed. Doing so can cause you to ingest an unsafe amount of fluoride. Naturally, this is much more of a risk with children than adults.

Another potential risk factor is having a higher water intake than the average person. This may be the case if you:

• Are an athlete
• Eat a high-protein diet
• Are expecting a child
• Have a medical condition or are taking medication that causes you to lose water

If any of the above apply to you and you primarily drink fluoridated tap water, it’s theoretically possible that you’ll consume significantly more fluoride than optimal. Cooking food in fluoride-containing water also increases your fluoride intake.¹²

Too Little Fluoride Exposure

On the other hand, it’s also possible to get less than optimal fluoride. In this case, you could put yourself at higher risk for cavities, acid erosion, and sensitive teeth. Fluoride helps prevent these conditions by remineralizing your teeth.

You may not get optimal fluoride levels if:

• You only drink bottled water
• You use a reverse osmosis filter at home
• You don’t use fluoride toothpaste

On the other hand, if you’d rather avoid fluoridated water, you’ll still get plenty of fluoride by simply using fluoride toothpaste. Too-low fluoride levels are likely to be an issue if you don’t have access to quality dental care or don’t practice good oral hygiene.

For example, many toothpastes that use hydroxyapatite as an alternative to fluoride are available. But if you’re not using a toothpaste that contains either fluoride or hydroxyapatite, you’re missing out on the boost in remineralization that these ingredients provide.

Are There Side Effects of Fluoride in Drinking Water?

Studies found that fluoridated water at optimal levels is unlikely to cause harmful side effects.⁷ However, excessive fluoride in water can lead to dental fluorosis, skeletal fluorosis, or other conditions.

These are the effects of specific fluoride concentrations in water:

• 1.5 milligrams per liter of water ⁠— High enough to benefit dental health but low enough to avoid adverse effects
• 3 milligrams per liter of water ⁠— May cause adverse effects on children’s cognitive ability⁷

Most water authorities worldwide aim for a fluoride concentration of 1.5 milligrams per liter or below.

If you’re in a developed country, it’s unlikely that your level of fluoride intake will be too low or high. But if you avoid fluoride in drinking water, you can still get the benefits of remineralization by using toothpaste with either fluoride or hydroxyapatite.

Summary

Fluoride is good for your teeth in low doses but unsafe in high doses. Many jurisdictions worldwide add fluoride to the water supply or reduce it to achieve the optimal amount for dental health.

To maximize the benefits of fluoride and minimize the risks, you can do the following:

• Learn about your local water supply, and use a reverse osmosis filter if you’d rather avoid fluoride
• Use fluoride toothpaste (or hydroxyapatite toothpaste, which is the best-established alternative for tooth remineralization)
• Don’t use other fluoride-containing dental products without consulting your dentist
• Make sure your children never swallow fluoride toothpaste

If you do all of the above, you and your children are unlikely to be at risk of any fluoride-related health problems, but you’ll enjoy the dental health benefits of topical fluoride.