How Does What You Eat Affect Your Teeth?

The World Health Organization advises getting less than 10% of your daily energy from free sugars, and less than 5% for extra benefit. For an adult, 5% works out at roughly six teaspoons a day (WHO sugars guideline, 2015). How often you have sugar matters too, so keep sweet things to mealtimes.

Free sugars are those added to food and drink, plus the sugars in honey, syrups and fruit juice. In a systematic review written to inform the WHO guidelines, lower intakes of free sugars went with less decay (Moynihan and Kelly, 2014). Each time sugar arrives, bacteria in plaque make acid that softens enamel, and saliva needs time to repair it, so grazing and sipping give teeth little rest (healthdirect, tooth decay).

A dessert with dinner is easier on teeth than the same amount nibbled through the afternoon. Make plain water your drink between meals, and choose savoury snacks such as cheese, nuts or crunchy vegetables over biscuits or dried fruit. No diet repairs a cavity, and we don’t ask for a perfect diet. We look at your usual day and pick one or two changes you’ll keep.

• World Health Organization. Guideline: sugars intake for adults and children (2015)
• Moynihan PJ, Kelly SAM. Effect on caries of restricting sugars intake: systematic review to inform WHO guidelines. Journal of Dental Research. 2014. PubMed 24323509
• healthdirect (Australian Government). Tooth decay

At Australian levels, yes. After reviewing the evidence in 2017, the NHMRC backed community water fluoridation as a safe way to cut decay (NHMRC, 2017), and fluoride toothpaste is strongly supported too. A Cochrane review found that fluoride toothpaste prevents decay (Walsh et al., 2019). For young children, ask us how much toothpaste to use and which strength.

The habit with the best evidence is brushing twice a day with fluoride toothpaste, then spitting out instead of rinsing, so the fluoride stays on your teeth. Once a day, clean between your teeth too. How much toothpaste and what strength suits a child depends on their age, so ask us at their check-up.

If you have doubts, bring them. We’ll go through the research, your own or your child’s risk of decay and the alternatives, and you decide what suits your family. We don’t tell anyone to avoid fluoride, and we won’t pressure you to use it. Fluoride doesn’t replace limiting how often sugar reaches your teeth, and it doesn’t repair a cavity once decay has broken through the enamel.

• National Health and Medical Research Council. 2017 Public Statement – Water fluoridation and human health
• Walsh T, et al. Fluoride toothpastes of different concentrations for preventing dental caries. Cochrane Database of Systematic Reviews. 2019. PubMed 30829399

Often, yes. Plenty are acidic, sugary or both, which wears enamel and feeds decay. Keep them to mealtimes and chase them with water, rather than sipping slowly.

Sour or fizzy drinks, including kombucha, sports drinks and juice, are acidic and can wear enamel. Juice also counts as a source of free sugars, as do honey and syrups (WHO sugars guideline, 2015). The slower you sip, the longer your teeth sit in acid and sugar, and the less time saliva has to help them recover (healthdirect, tooth decay).

Practical changes: have them with a meal, follow them with water, and make water your drink between meals. We don’t ask you to give them up, and we don’t run detox plans. A dry mouth makes the effect of acid worse, so tell us if your mouth is often dry. If you enjoy a drink like this, ask us how often it’s reasonable for your own teeth.

• healthdirect (Australian Government). Tooth decay
• World Health Organization. Guideline: sugars intake for adults and children (2015)

Tell your dentist and your GP, especially if it began with a new medicine. Your doctor can review the cause, and we can suggest ways to protect your teeth in the meantime. Don’t stop a prescribed medicine on your own.

Saliva is your teeth’s natural defence. It washes food away, dilutes acid and helps enamel recover after eating. Many common medicines reduce saliva, and so can breathing through your mouth at night, some health conditions and not drinking enough water. With less saliva, teeth have less protection from acid (healthdirect, tooth decay), so decay becomes more likely.

In the meantime, take sips of water, keep sweet and acidic food and drinks to mealtimes and keep up brushing with fluoride toothpaste twice a day. Ask us at your check-up about other ways to protect your teeth. If your mouth is dry on waking, tell us, because it can mean you breathe through your mouth at night, and we can talk through whether a sleep question is worth raising with your doctor.

• healthdirect (Australian Government). Tooth decay

Supplements aren’t something we sell or prescribe. Eating a varied diet is good for teeth and gums. For a possible deficiency, an accredited dietitian or your GP is the right person to check.

Food that’s good for your teeth overlaps a lot with food that’s good for the rest of you, and the World Health Organization treats oral health as part of overall health (WHO oral health fact sheet). Cutting back on free sugars, tobacco and alcohol helps your mouth and the rest of you. A supplement doesn’t replace brushing with fluoride toothpaste or limiting how often sugar reaches your teeth.

If you think you’re low in a nutrient, your GP or a dietitian can check, and test where that’s needed. Tell us about any supplements you take, because they’re part of your health history. We don’t run detox programs, and dental care isn’t a treatment for conditions elsewhere in your body. Our role is the mouth: food and drink habits, dry mouth, cleaning and fluoride, and what to change first.

• World Health Organization. Oral health – fact sheet