Fluoride

The form of fluorine that protects teeth against decay. Most Americans get it from fluoridated tap water, toothpaste and food and drinks made with that water.

How much you need

The official Adequate Intake for adults, per day:

Age	Men	Women	Pregnancy	Breastfeeding
19–50 years	4 mg	3 mg	3 mg	3 mg
51–70 years	4 mg	3 mg	—	—
Over 70	4 mg	3 mg	—	—

These are Adequate Intakes, set at the intakes that most reduce tooth decay without causing dental fluorosis. Fluoridated tap water, and food and drink made with it, provide about 60% of Americans' fluoride; the U.S. Public Health Service recommends 0.7 mg per litre in community water.

People aged 18 fall in the official 14–18 group — 3 mg a day, including in pregnancy and when breastfeeding. Its upper limit is the same as for adults, 10 mg. Pregnancy and breastfeeding change what you need — confirm yours with your midwife, obstetrician or doctor.

Upper limit

Age	Men	Women	Pregnancy	Breastfeeding
19–50 years	10 mg	10 mg	10 mg	10 mg
51–70 years	10 mg	10 mg	—	—
Over 70	10 mg	10 mg	—	—

The upper limit covers fluoride from all sources. It is the most that is unlikely to cause harm, not a target, and was based on the levels associated with dental and skeletal fluorosis.

What it does

Fluoride, the ionic form of fluorine, protects teeth against decay by inhibiting the loss of tooth mineral and the activity of bacteria in dental plaque, and by helping teeth remineralise ^[1]. It also helps stimulate the formation of new bone ^[1]. About 80% or more of the fluoride swallowed is absorbed; in adults about half is kept, almost all of it in bones and teeth, and the rest is excreted in urine ^[1].

Forms

Most fluoride comes from fluoridated water, food and drink made with it, and toothpaste and other dental products ^[1]. Toothpaste usually contains 1,000 to 1,100 mg/L, about 1.3 mg in a quarter teaspoon, and adults swallow about 0.1 mg a day from it ^[1]. Few supplements contain fluoride, usually 0.25 mg ^[1]. The antifungal drug voriconazole contains fluoride, and long-term use can raise blood fluoride ^[1].

Where it comes from

Tea, black, brewed (varies with the water used)1 cup0.07–1.5 mg
Coffee, brewed (varies with the water used)1 cup0.22 mg
Shrimp, canned3 ounces0.17 mg
Bottled water with added fluoride (up to)fortified1 cup0.17 mg
Raisins¼ cup0.08 mg

How these five were chosen: The five foods with the most fluoride per serving in the NIH fact sheet's food table. Fortified foods are marked.

How far one serving goes toward a day's fluoride

How far one serving goes toward a day's fluoride
Item	Percent of the adult daily amount (4 mg)
Black tea, brewed	2–38%
Coffee, brewed	6%
Shrimp, canned	4%
Bottled water (fluoride)	4%
Raisins	2%

Against the adequate daily amount for adults 19 to 50: 4 mg, the highest value for men or women in that age range. Where a food varies by brand, the bar shows the lowest figure and the label the full range. Computed from the figures on this page, taken from the NIH fact sheet.

Getting the most from it

Brewed tea contains more fluoride than most foods, because tea plants take it up from the soil — 0.07 to 1.5 mg a cup ^[1]. Most foods not made with fluoridated water contain only traces ^[1]. Bottled water usually has no added fluoride; when it does, the FDA caps the total at 0.7 mg/L ^[1]. Private wells vary ^[1].

In the United States

Most Americans get enough fluoride from food, fluoridated water and food made with it ^[1]. The Environmental Protection Agency estimates typical adult intake from food and drink, including fluoridated water, at 2.9 mg a day ^[1].

Who is most likely to run low

People whose water supply contains little or no fluoride, such as some private wells — in 2020, 62.9% of Americans had fluoridated community water ^[1]

What deficiency looks like

No criteria for adequate or low fluoride status have been established, and individual status is not usually assessed ^[1]. Without enough fluoride, the risk of tooth decay rises; decay can cause pain, tooth loss and infection ^[1].

What the evidence supports, and what it doesn't

Established. Water fluoridation prevents tooth decay: a 2015 Cochrane review of 20 studies found that children with fluoridated water had 35% fewer decayed, missing or filled baby teeth and 26% fewer in their permanent teeth ^[1]. Studies in Australian adults found 11% to 24% less decay with long exposure to fluoridated water ^[1]. Fluoride supplements reduce decay in children without fluoridated water ^[1].

Not supported by trials. Fluoride supplements in pregnancy: a 2017 Cochrane review found no evidence that they prevent tooth decay in children ^[1]. No studies have tested fluoride supplements against decay in adults ^[1].

Mixed. Bone fractures: observational studies of fluoridated water and fractures disagree, and trials of fluoride supplements have had conflicting results ^[1].

Too much

Too much fluoride while teeth are forming, in infancy and childhood, causes dental fluorosis — usually faint white lines or flecks, rarely brown stains or pitting ^[1]. Mild fluorosis does not harm oral health, moderate or severe fluorosis affects 1.4% to 1.8% of children and adolescents, and there is no indication that the recommended level in tap water causes severe fluorosis ^[1]. Chronic excess can cause skeletal fluorosis, from joint stiffness to osteoporosis, but it is extremely rare in the United States ^[1]. A 2024 National Toxicology Program review concluded with moderate confidence that water fluoride above 1.5 mg/L is associated with lower IQ in children; it did not address the recommended 0.7 mg/L, and a 2023 meta-analysis found no link at U.S. fluoridation levels ^[1].

Medicines that interact

Fluoride has no known clinically relevant interactions with medicines ^[1]. Long-term use of the antifungal voriconazole can raise blood fluoride; its prescribing information advises stopping it if skeletal fluorosis develops ^[1].