Oral Health›Diet and lifestyle

Sugar, Acid and Your Teeth

Sugar feeds the bacteria that cause tooth decay, and acidic drinks can wear enamel away. How often you have them matters as much as how much. Here is what health bodies advise.

Updated September 2026·By the OHA editorial team·8 min read·How we write
Key takeaways
  • Bacteria in plaque turn sugar into acid, and that acid attacks the enamel (the hard outer layer of your teeth). Over time this causes decay.
  • How often you have sugar matters: every sugary snack or drink starts a new acid attack, so keep sugary food and drinks to mealtimes.
  • Acidic drinks, including sugar-free fizzy drinks, sports drinks and fruit juice, can slowly wear enamel away. This is called dental erosion.
  • Water and milk are the most tooth-friendly drinks between meals.
  • Do not brush straight after something acidic. Advice on how long to wait ranges from at least 30 minutes to an hour.

Sugar is a main cause of tooth decay, and acid causes a different problem, dental erosion. Small changes to when and what you eat and drink make a real difference, and the advice from health bodies in the UK, Australia and the US is broadly the same.

How does sugar cause tooth decay?

Your mouth is full of bacteria. Some of them live in plaque, the sticky, colourless film that builds up on your teeth. The US National Institute of Dental and Craniofacial Research (NIDCR) explains that whenever you eat or drink something containing sugar or starch, these bacteria use it to make acids, and the acids begin to eat away at the enamel.

Minerals in saliva, together with fluoride from toothpaste and water, help the enamel repair itself: NIDCR describes a tug-of-war that goes on all day. If the acid wins too often, the enamel loses minerals. A white spot may appear, which is a sign of early decay, and NIDCR says decay can still be stopped or reversed at this stage. If it carries on, a hole (cavity) forms, which is permanent damage that a dentist has to repair with a filling.

The World Health Organization (WHO) calls the consumption of free sugars the most common risk factor for tooth decay, and the NHS describes sugar as one of the main causes of tooth decay.

Why does how often matter as much as how much?

The Oral Health Foundation points out that it is not just what you eat that matters but how often you eat. Every time you have something sugary, your teeth are under acid attack, and this can last for up to an hour. If you snack or sip throughout the day, your teeth have little time to recover.

The American Dental Association (ADA) adds that food eaten as part of a meal causes less harm than lots of snacks, because more saliva is released during a meal, which helps wash food away and lessens the effect of acids.

Practical steps from these bodies:

  • Keep sugary food and drinks to mealtimes. The NHS and the Oral Health Foundation both give this advice.
  • Choose water or milk between meals, and pick savoury snacks when you can (Oral Health Foundation). The ADA notes that some foods, including cheese and peanuts, counter the effects of acid attacks.
  • Chew sugar-free gum after eating to increase saliva, which protects teeth (Oral Health Foundation).
  • Have nothing sugary after brushing at bedtime. NIDCR gives this advice for children because saliva flow falls during sleep, so teeth are less able to repair themselves.

What about fruit, juice and dried fruit?

The NHS says the sugars in whole fruit and vegetables are less likely to cause decay because they are contained within the structure of the food. Juicing or blending releases those sugars, and once released they can damage teeth. The NHS advises limiting fruit juice and smoothies to 150ml a day in total, drunk with meals, and eating dried fruit as part of a meal rather than as a snack between meals. The ADA notes that dried fruit is sticky and clings to teeth.

What is dental erosion?

healthdirect Australia describes dental erosion as acid softening and wearing away the enamel surface of your teeth. Unlike decay, it does not involve bacteria (Oral Health Foundation). The acid can come from food and drink, or from your stomach if you vomit often or have reflux.

healthdirect says tooth enamel cannot grow back once it has gone. Teeth affected by erosion can:

  • become discoloured, as the yellowish layer underneath (dentine) shows through
  • become sensitive to heat and cold
  • look shorter as they wear down
  • chip or break more easily, or have sharp edges

Acidic food and drink listed by healthdirect and the Oral Health Foundation include fruit juices, soft drinks (including sugar-free ones), sports and energy drinks, citrus fruits, vinegar, wine and cider. Sipping acidic drinks often increases the time acid is in contact with your teeth, according to healthdirect. A dry mouth makes erosion worse, because there is less saliva to wash away and neutralise acid.

Fizzy drinks, sports drinks and juice

Sugary drinks can harm teeth twice over. The Australian Dental Association says they can cause both tooth decay (from the sugar) and tooth erosion (from the acid). It says a 600ml bottle of soft drink can contain up to 16 teaspoons of sugar; the NHS says a single can of cola can contain as much as 9 cubes of sugar.

Switching to a sugar-free version removes the sugar but not the acid. The Australian Dental Association says sugar-free soft drinks, energy drinks and sports drinks are still acidic and can cause erosion if drunk regularly. The ADA adds that carbonation itself raises the acid level of a drink, whatever its flavour.

For weekend or social sport, the Australian Dental Association says water is the best drink. Sports drinks expose teeth to sugar and acid, and can be more damaging if you drink them when dehydrated.

If you do have an acidic drink, these steps reduce the harm:

  • Have it with a meal rather than sipping it over a long time (Oral Health Foundation, healthdirect).
  • Use a straw, to limit contact with your teeth (healthdirect, Oral Health Foundation).
  • Swallow rather than swishing or holding it in your mouth (ADA, Oral Health Foundation).
  • Afterwards, rinse with water, or have milk or cheese, which help neutralise acid (healthdirect, ADA, Oral Health Foundation).

For everyday drinking, water is best. The ADA says it helps wash away bacteria and weakens acids, and the Australian Dental Association recommends tap water because in many Australian communities it contains added fluoride.

How long should you wait to brush after acidic food or drink?

Brushing while enamel is softened by acid can remove tiny amounts of it, as the Oral Health Foundation explains. Patient advice from the bodies we checked is to wait, but they give different times:

  • healthdirect Australia: wait at least 30 minutes after an acidic drink or vomiting, because acid softens enamel for about 20–30 minutes. You can rinse with water or a fluoride mouthwash while you wait.
  • Oral Health Foundation (UK): wait at least one hour after eating or drinking before brushing.
  • American Dental Association: wait an hour after eating acidic foods.

Delivering Better Oral Health, UK guidance written for dental teams, adds that there is no strong evidence that the timing of toothbrushing is of great importance.

How much sugar is too much?

Guidance on daily sugar limits differs between organisations, and they do not all measure the same thing. "Free sugars" (used by WHO and the NHS) means sugar added to food and drink plus the sugar in honey, syrups and fruit juice. "Added sugars" (used in the US) is a similar but separate measure.

  • WHO: limit free sugars to less than 10% of total energy intake, and ideally less than 5%, to minimise the risk of decay throughout life. WHO also recommends that children under 2 have no sugar-sweetened drinks.
  • UK (NHS): free sugars should be no more than 5% of daily energy. That is no more than 30g a day for adults (roughly 7 sugar cubes), 24g for children aged 7 to 10, 19g for ages 4 to 6, 14g for ages 2 to 3, and 10g at age 1. Sugar should not be added to food or drinks for babies.
  • Australia: the Australian Dental Association gives a recommended amount for the average adult of 6 teaspoons (24g) a day.
  • US: the ADA reports that the Dietary Guidelines for Americans 2025–2030 say a healthy diet should not include any added sugars, and that if you do have them, you should limit yourself to no more than 10g in one meal.
When to see a dentist
  • A tooth is sensitive to hot, cold or sweet food and drink.
  • You notice white, brown or black spots, or a hole, on a tooth.
  • Your teeth look more yellow, shorter, or have thin or chipped edges.
  • You vomit often or have acid reflux. Also speak to your doctor, as healthdirect advises.

Frequently asked questions

Are sugar-free fizzy drinks safe for my teeth?

Not entirely. The Australian Dental Association says they are acidic and can cause erosion if you drink them regularly.

Is fruit bad for my teeth?

Whole fruit is fine: the Australian Dental Association says whole fruit eaten in moderation does not damage teeth. For juice and smoothies, the NHS advises no more than 150ml a day, with meals.

Does chewing sugar-free gum help?

Yes. healthdirect and the Oral Health Foundation both say it increases saliva, which helps dilute and neutralise acid.

Can early decay be reversed?

At the white-spot stage, NIDCR says decay can be stopped or reversed with minerals from saliva and fluoride. Once a cavity has formed, it needs a filling.

Sources

  1. Tooth decay, NHS, accessed September 2026
  2. Sugar: the facts, NHS, accessed September 2026
  3. Sugars and dental caries, World Health Organization, accessed September 2026
  4. The tooth decay process: how to reverse it and avoid a cavity, National Institute of Dental and Craniofacial Research, accessed September 2026
  5. Tips to reduce risks of grazing all day, Oral Health Foundation, accessed September 2026
  6. Dental erosion, Oral Health Foundation, accessed September 2026
  7. Dental erosion, healthdirect Australia, accessed September 2026
  8. Sugary drinks, Australian Dental Association, accessed September 2026
  9. Sports drinks, Australian Dental Association, accessed September 2026
  10. Diet and dental health, American Dental Association (MouthHealthy), accessed September 2026
  11. Dietary acids and your teeth, American Dental Association (MouthHealthy), accessed September 2026
  12. Delivering better oral health, chapter 7: tooth wear, Department of Health and Social Care and NHS England, accessed September 2026

This article is general information about oral health. It is not a diagnosis or a substitute for advice from a dentist or doctor who knows your situation. If you have pain, swelling, bleeding that does not settle, or a problem that is getting worse, see a dental professional. In an emergency, contact your local emergency service.

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