During a recent visit to Wholefoods I was amazed at the proliferation of alternative branded toothpastes that don’t contain fluoride. This got me thinking about fluoride and the question of fluoride in toothpaste: why it’s included and whether it should be.
So, what is fluoride?
Fluoride is a natural mineral, that is commonly found in nature as the compounds fluorite, fluorapatite and cryolite. It is renowned for strengthening teeth, helping to prevent cavities and related diseases.
It is naturally found in water and many foods such as tea, coffee, shellfish, potatoes and grapes.
How does fluoride protect teeth? The science
Every day, minerals are added to and lost from a tooth’s enamel layer through two processes, demineralisation and remineralisation. Minerals are lost (demineralisation) from a tooth’s enamel layer when acids, formed from plaque bacteria and sugars in the mouth, attack the enamel. Minerals such as fluoride, calcium and phosphate are re-deposited (remineralisation) to the enamel layer from the foods and waters consumed. Too much demineralisation without enough remineralisation to repair the enamel layer leads to tooth decay.
Fluoride helps prevent tooth decay by making the tooth more resistant to acid attacks from plaque bacteria and sugars in the mouth. It also reverses early decay. In children under 6 years of age, fluoride becomes incorporated into the development of permanent teeth, making it difficult for acids to demineralise the teeth.
Fluoride also helps speed remineralisation as well as disrupts acid production in already formed teeth of both children and adults. Children who have fluoride when their teeth are developing tend to have shallower grooves in their teeth, so plaque can be more easily removed.
How much fluoride is needed?
This varies according to body mass (weight).
There have been many studies aimed at understanding average intake of fluoride in various communities from food, drink and dental supplements and products and the relationship to dental decay. A US study concludes that the Adequate Intake (AI) is set at 0.05 mg/kg/day. This is because it confers a high level of protection against dental decay and is associated with no known unwanted health effects.
This typically ranges from a daily total requirement of 0.7milligrams (mg)/day for 1-3 year olds to 3-4mg/day for adults.
All water contains some fluoride but only 10% of places have enough natural fluoride in their water to benefit the dental health of their estimated 1.5 million people. A concentration of 1 part of fluoride for every million parts of water (1ppm) has been shown to have the best effect, reducing dental decay by 50%. Despite most people in the UK thinking that fluoride is added to their drinking water, actually fluoridation only happens in West Midlands, Yorkshire and Tyneside, affecting a further 5.5 million people. Fluoride is not added to the water in Scotland, Wales or Northern Ireland.
The largest water provider, Thames Water state on their website “We do not add fluoride to our water. The decision to fluoridate water supplies is taken by your local strategic health authority – not by Thames Water. Thames Water supplies have a natural concentration of between 0.1 – 0.4 mg/l. In the areas to the south and west of Reading the concentrations can be higher, typically around 1 mg/l.”
Fluoride is also in some foods and drinks, for example fish and tea. Some countries add fluoride to their table salt and milk instead of to the water supplies. One cup of tea contains between 0.3 mg and 0.5 mg of fluoride.
What about fluoride in toothpaste?
Toothpaste is the simple reason why water fluoridation has not become more universally practiced in the developed world. The first commercial fluoride toothpaste (Crest) became available in 1955. Today 94% of people use a toothpaste containing fluoride, accounting for the significant decline of tooth decay in the developed world over recent decades. We now recognise that the protection that fluoride provides teeth is best achieved by regularly brushing your teeth throughout your lifetime with toothpaste containing the recommended amount of fluoride. To limit the risk of toxicological side effects, such as dental fluorosis, NHS guidance is:
- Children under 3 years old should brush twice daily, with a smear of toothpaste containing at least 1,000ppm fluoride
- Children between 3 and 6 years old should brush at least twice daily with a pea-sized amount of toothpaste containing more than 1,000ppm fluoride
- Adults should brush at least twice daily with a toothpaste containing 1,350-1,500ppm fluoride.
Fluoridated water supplies in developing countries where people do not have access to fluoride toothpaste can still play a positive role in tooth care. But a government’s ultimate goal should be improving access to affordable fluoride toothpaste, as this is where topically applied fluoride is at its most effective.
What are the dangers of too much fluoride?
A condition called dental fluorosis can sometimes occur if a child’s teeth are exposed to too much fluoride when they’re developing. Read more about looking after children’s teeth and looking after your baby’s teeth.
Mild dental fluorosis can be seen as very fine pearly white lines or flecking on the surface of the teeth. Severe fluorosis can cause the tooth’s enamel to become pitted or discoloured.
It’s uncommon in the UK for fluorosis to be severe enough to seriously affect the appearance of teeth. This is because fluoride levels in water are carefully monitored by the Drinking Water Inspectorate (DWI) and adjusted if necessary. All toothpaste is labelled with warnings for parents to monitor use, thus prevent children from swallowing paste.
Aside from the aesthetic issue of fluorosis, there have been concerns that fluoride may be linked to a variety of health conditions. NHS UK state that reviews of the risks have so far found no convincing evidence to support these concerns.
However, there are still many people who object to fluoride being added to their water. The main objection is that it is effectively government-orchestrated mass medication, in which citizens aren’t asked for their consent or able to opt out (except by drinking bottled water).
Beyond this ethical dilemma, there are other arguably reasonable medical objections to water fluoridation including:
- The doses of fluoride individuals receive go to everyone using the water supply, regardless of their age or state of health
- Fluoride accumulates in the body over time, especially in the bones and the pineal gland in the brain (which regulates the release of some hormones, including melatonin)
- Fluoride can affect the functioning of the thyroid gland
- Some academic research suggests that fluoride may damage the brain and lower IQ levels
- Fluoride has also been linked to occurrences of bone damage
Research in to risk
Regarding claims that water fluoridation might be a cause of ill health, some 370 million people worldwide, including six million in England and 200 million (70% of the population) in the United States have had an artificially fluoridated water supply for over 50 years. Routine monitoring of health in these areas has not revealed any associated health problems.
Recent large reviews that have been carried out include:
- Public Health England: Water fluoridation health monitoring report for England (PDF, 1.51Mb) – in 2014 (read the NHS website’s coverage of this report)
- NHS Centre for Reviews and Dissemination: A systematic review of water fluoridation (PDF, 6.22Mb) – in 2000
- Centers for Disease Control and Prevention (US): Recommendations on selected interventions to prevent dental caries, oral and pharyngeal cancers and sports-related craniofacial injuries (PDF, 69kb) – in 2002
- US Department of Health and Human Services Community Preventive Services Task Force: Community water fluoridation – in 2013
- Royal Society of New Zealand: Health effects of water fluoridation (PDF, 1Mb) – in 2014
- Cochrane Oral Health Group: Water fluoridation for the prevention of dental caries – in 2015
Overall, these reviews found that water fluoridation appears to contribute to reduced tooth decay levels and doesn’t seem to be associated with any significant health risks.
Having read around this subject, my personal conclusion is that fluoride in toothpaste is definitely a benefit. There seems to be a trend towards assuming that natural is best, possibly compounded by mistrust of institutional advice. However, I didn’t find any evidence to support this.
That said, I meet many people who swear by making their own natural organic toothpastes. I absolutely respect the right of people to decide for themselves and if they’ve found something that works for them, they will feel motivated to brush their teeth regularly. And that can only be a good thing.