The Fluoride Question: Should We Use Fluoride Products or Avoid Them, If Our Goal is Healthy Longevity?

This article is not intended as, and should not be taken as, medical advice.

by Nils Osmar

Fluoride is one of those topics where the “sides” tend not to listen to each other. One camp highlights the dental benefits while downplaying the side effects; the other camp focuses on fluoride’s well-established toxicity while downplaying the possible benefit to our dental welfare.

Some Key Benefits of TOPICAL Fluoride

The reality is that fluoride has a real, well-documented benefit for teeth. This matters because keeping our teeth healthy and intact as long as possible is essential to healthy longevity. It’s important to know, though, that the benefit of fluoride is overwhelmingly topical, happening at the surface of the tooth.

Some Key Dangers to Be Aware Of

Fluoride’s downsides are at their heart systemic, tied to how much of the compound we swallow and absorb over time.

The most serious concern is neurotoxicity: a 2024 review by the U.S. National Toxicology Program concluded, with “moderate confidence,” that higher fluoride exposures — drinking water above 1.5 mg/L, roughly double the level used in U.S. water fluoridation — are consistently associated with lower IQ in children, while cautioning that more research is needed at lower levels.

Other issues, again documented mainly at higher systemic exposures, include dental and skeletal fluorosis and interference with the proper functioning of our thyroid glands. The common thread is that these effects track total swallowed exposure over time — not the topical use we’re about to discuss.

Hidden Dietary Sources

It’s worth noting that almost no one avoids fluoride entirely. Even people who filter their water often drink coffee or tea, both of which naturally contain fluoride. So it isn’t a question of zero versus some — it’s a question of being deliberate about where your exposure comes from and how much you actually take into your body.

Fluoride is also present in most of the food we eat, because it’s in the water that they absorbed through their roots as they’re growing. We can’t avoid it entirely unless we’re growing all of our own food and filtering the water that we use in our gardens.

My main focus in this article will be on the use of dental products, and trying to clear up some confusion and misinformation about their use.

Is fluoride absorbed through the lining of our mouths?

This is the question that generates the most controversy and confusion, largely because people conflate two different things: fluoride getting into your mouth tissues and saliva (which clearly happens, and is key to its dental benefits) versus fluoride crossing the mouth lining to get into your bloodstream (which does occur, but is miniscule, for example, compared to how much we would get from drinking a cup of coffee).

A fluoride-and-oral-health review summarizing the data puts it plainly: absorption across the oral mucosa “is limited and probably accounts for less than 1% of the daily intake.”

The reason is chemistry. Fluoride travels as a charged ion (F⁻) that crosses fatty cell membranes poorly. It only slips across easily when it picks up a proton to become hydrogen fluoride (HF), and that requires acidity. Your mouth sits near neutral pH, so little HF forms and little crosses. Your stomach is strongly acidic, so HF forms readily and absorption is fast — 70–90% of swallowed fluoride is absorbed (closer to 100% for the sodium fluoride in dental products).

The takeaway is that the fluoride that reaches our bloodstream from toothpaste or rinse comes almost entirely from the portion we inadvertently swallow, not from absorption through our gums or cheeks. The single most effective way to deal with this is to spit thoroughly, and take care to avoid swallowing when brushing our teeth.

The “Pea Sized Dollop of Toothpaste” Question

One source of confusion among those trying to maximize fluoride’s benefits while minimizing its risks is that we’re told to use a tiny pea-sized dab of toothpaste to “minimize exposure” — but that it’s fine to swish with a whole capful of fluoride rinse.

Two facts help make sense of this apparent contradiction.

The first is that standard toothpaste has about 1,450 ppm fluoride. A rinse like ACT contains 0.05% sodium fluoride — which the label lists as 0.02% fluoride ion, or about 200 ppm. The rinse is seven times more dilute than the paste.

Second, the “use a small amount of toothpaste” rule is actually an ingestion-control measure aimed mainly at young children.

The reason is that kids under about six (who are at the most risk of developing health problems associated with fluoride exposure) can’t spit reliably and swallow much of what’s on the brush, and while their tooth enamel is still forming (roughly birth to age eight), chronically swallowing too much fluoride can permanently mottle the developing teeth — a condition called dental fluorosis.

Hence, the rule suggesting “rice-grain for toddlers, pea-sized for preschoolers”.

Fluoride rinses such as ACT are not intended or recommended for young children, as stated clearly on the label.

For an adult who spits, does the recommendation to use a tiny amount of fluoride toothpaste still make sense? I would question it actually. Our enamel formed decades ago, so the fluorosis window has closed, and spitting handles the rest. The difference between a pea and a full ribbon — even allowing for the residue you can’t spit out — is a few hundredths of a milligram, trivial next to a cup of tea. Since the benefit of fluoride is topical, I actually use a fluoride toothpaste with a full ribbon. I’m not saying you should, but it makes sense to me personally to do so. But I take care not to swallow, and I rinse thoroughly about a half hour later.

Getting the most benefit for the least systemic dose

Because the benefit is topical and the risk is systemic, we can push the two apart:

  • Spit after brushing, then delay rinsing. Rinsing with water right after brushing washes away the concentrated fluoride film your paste just laid down. Spitting and leaving it — then avoiding eating or drinking anything for 30 minutes — provides more benefit for our teeth, with no increase in what we absorb.
  • Skip the fluoride rinse after brushing. Following 1,450 ppm paste immediately with a 200 ppm rinse just washes the stronger dose off and replaces it with a weaker one.

Slowing absorption of the tiny amount you do swallow

If you’d like to blunt the tiny fraction that is swallowed when using fluoride toothpaste, there are things that can help. Fluoride binds to calcium and magnesium in the stomach, forming compounds the gut can’t absorb well, so they are excreted instead.

In controlled human studies, taking fluoride with food cut absorption by about 47%, and taking it with milk/dairy lowered how much reached the blood substantially (bioavailability dropping to roughly 50–79%).

The effect is strongest when the calcium is in your stomach at the same time as the fluoride. For example, having calcium-containing food or a glass of milk around the time you use fluoride products means whatever you swallow is more likely to be bound and carried out rather than absorbed.

The same advice would apply to those concerned about the “naturally occurring” fluoride in coffee and tea. There are longevity benefits associated with both beverages, which (in my opinion) outweigh the risks. I use filtered water when preparing them (to avoid adding even more fluoride), and try to drink them at a time when I have some food in my stomach, or consume them along with a little dairy.

I’ve read advice online to use “calcium chews” right after brushing; this makes no sense to me. If we do so, we’ll just be negating the benefit of coating our teeth temporarily with fluoride.

Can we remove fluoride that’s already in the body?

If you poke around online, you’ll find products promising to “detox” the fluoride already in our bodies. There is actually evidence for one product that works (which I’ll describe below), but most of them, IMO, are a waste of money.

The majority of the fluoride the human body retains is actually stored in bones and teeth, and once it’s in bone it leaves slowly, as bone naturally remodels over time. Health agencies note that bone fluoride declines gradually after exposure drops, but the exact human timeframe isn’t well established.

What makes sense (in terms of removal), in my opinion, would be to:

  • Support our kidneys. They clear roughly 50–70% of fluoride intake through urine, so healthy kidney function and good hydration (with non-fluoridated water) are the real workhorses of elimination.
  • Get adequate calcium, magnesium, vitamin D, and vitamin C. These are used in managing fluorosis, though much of the supporting evidence is from animal studies and observational settings rather than large human trials.
  • Reduce ongoing intake. Lower what’s coming in, and your body’s slow bone turnover gradually draws your stores down on its own.

The “Fluoride Detox” That Works — Or Appears To

  • I said above that most “detox products” are highly questionable.
  • Tamarind is an interesting exception.
  • In one small human study, 10 g daily raised urinary fluoride excretion by about 37%.
  • The evidence for using tamarind to remove fluoride from our bodies is preliminary, but real.

The bottom line

Fluoride’s benefit to teeth is real, and it happens mostly at the surface — topically. Its risks are real too, and they come mostly from swallowing and accumulating it over years.

These truths don’t contradict each other; they point to a straightforward approach: Use fluoride toothpaste for the topical benefit, spit rather than swallow, don’t rinse right after brushing or using a fluoride rinse; and don’t lose sleep over the size of the dab.

If you want to be extra careful about the small swallowed fraction, timing it around calcium-containing food helps.

To minimize internal exposure, I personally use a water filter that removes fluoride — and try to be aware of the amount I am getting from coffee and tea.

This article is general information, not medical or dental advice; for personal decisions, talk with a professional who knows your situation.

Sources

Nils Osmar is the Director of Rekindle School, an independent educational program in Seattle, Washington, established in 2002. He has several websites, exploring questions related to:

• Consciousness in today's Large Language Models

• Life extension and anti-aging

• News, politics, culture and the arts

Unless otherwise indicated, Nils is the author of all of the articles on this site. 

© Nils Osmar 2026.

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