Fluoride

Fluoride strengthens hydroxyapatite, the mineral in tooth enamel and bone, by incorporating into its structure as fluorapatite. The result is enamel that is more resistant to the acid produced when oral bacteria ferment sugars, reducing tooth decay. This effect is the basis for the NHS recommendation that everyone over 3 uses a toothpaste with 1,350 to 1,500 ppm fluoride.

The UK story on water fluoridation is uneven. Some communities have fluoridated water (added at around 1 mg per litre), others have low natural fluoride, and some have higher natural fluoride from local geology. Local authorities, in collaboration with the NHS, manage the fluoridation schemes that do exist.

Fluoride in the UK diet comes mainly from:

• Drinking water (varies by region; fluoridated supplies are around 1mg per litre)
• Tea (tea plants accumulate fluoride from soil; a strong cup of black tea contains around 0.1 to 0.4mg of fluoride)
• Some fish (particularly small fish eaten with bones, like tinned sardines)
• Toothpaste residues (although toothpaste is not intended to be swallowed)

Diet is a modest fluoride source compared with toothpaste, which is the main way most UK people get fluoride to their teeth.

The UK has not set a strict Reference Nutrient Intake (RNI) for fluoride. SACN gives safe intake ranges and the practical guidance focuses on dental health and toothpaste.

Fluoride is not classed as an essential nutrient in the same way as the vitamins and the minerals required for survival; the body does not stop working without it. The relevant effect of low fluoride status is increased tooth decay, not classical deficiency disease.

Children living in areas with low natural fluoride and no fluoridated supply have historically had higher rates of tooth decay. The NHS toothpaste guidance closes that gap regardless of water supply.

Dental fluorosis is the main safety concern from excess fluoride, and it is almost entirely a childhood issue from swallowing toothpaste during the years that permanent teeth are forming (under 8).

Mild dental fluorosis appears as small white spots or streaks on the permanent teeth. It is mainly cosmetic. Severe fluorosis (rare in the UK) can include enamel pitting.

NHS guidance to prevent fluorosis:

• Babies and children under 3: smear of toothpaste containing at least 1,000ppm fluoride, twice a day.
• Children 3 to 6: pea-sized amount of toothpaste containing 1,350 to 1,500ppm fluoride, twice a day.
• Children 7 and over, and adults: pea-sized amount of toothpaste containing 1,350 to 1,500ppm fluoride, twice a day.
• Supervise children under 7 when brushing. Encourage spitting out, not swallowing, toothpaste. Do not rinse with lots of water afterwards (this washes away the fluoride that is helping the teeth).

Skeletal fluorosis (much more serious, affecting bones) requires very high long-term intakes (multiple milligrams per day for years) and is not seen in the UK from any normal pattern.

Fluoride supplements (drops or tablets) were historically prescribed for children in low-fluoride areas; this is no longer routine NHS practice in most parts of the UK. Toothpaste at the right concentration for the child's age does the same job more reliably.

Children at higher risk of decay may be offered fluoride varnish at routine dental check-ups; this is applied by a dentist or dental nurse and is the current NHS standard.

Anyone with concerns about decay risk, fluorosis, or toothpaste choice for a child should ask their dentist at the next routine appointment.

• UK water fluoridation: check with your local water supplier or look up your postcode on your area's public health page to find out whether your tap water is fluoridated.
• Other minerals in bone health: Calcium, Phosphorus, Vitamin D, Magnesium, Vitamin K.

• NHS. Children's teeth: Brushing and toothpaste.
• NHS. Fluoride. nhs.uk/live-well/healthy-teeth-and-gums/fluoride.
• NHS. Vitamins and minerals: Others. Fluoride section.
• SACN. Dietary Reference Values for Food Energy and Nutrients for the United Kingdom. Department of Health Report 41 (1991).

This page is reference information for UK shoppers and parents. It is not medical or dental advice. Discuss fluoride concerns with your dentist at the next routine appointment.