Does sugar cause tooth decay?

Yes. EFSA, reviewing the evidence in 2022, calls it well established that dietary sugars are involved in tooth decay at all ages, and it could not find any intake at which the risk is not raised. Mouth bacteria turn sugar into acids that dissolve enamel and dentine. The human evidence comes from cohorts and population studies. In a 2025 meta-analysis of 9 cohorts, children under 6 who ate sugar had 1.59 times the odds of early childhood caries (95% CI 1.50 to 1.68). No randomized trial of cutting sugar has measured caries, and WHO found none that met its criteria.

Established. Advice on diet and feeding given to new mothers probably protects their children's baby teeth. A 2024 Cochrane review found a probable 15% lower risk of caries in primary teeth, a risk ratio of 0.85 (95% CI 0.75 to 0.97), across 3 trials and 782 children, on moderate certainty evidence. The advice covered diet and feeding as a whole, not sugar alone.

Unsettled. How little sugar is little enough has no clear answer. EFSA says the evidence cannot show the shape of the relationship or a level of intake at which caries risk is not increased. WHO's own cut-off of 10% of energy rests on moderate quality cohort data, and its 5% figure on very low quality data.

What the trials found

Why there are no trials of sugar itself

The direct test, cutting sugar in one group and not in another and counting cavities, is missing. WHO's review for its 2015 guideline found no randomized trials in children that met its criteria. The 2022 Cochrane review of 21 trials of high against low added sugar found one that reported dental health, and it recorded no events. Those trials lasted 14 weeks on average, too short for decay to show.

What the observational studies show

The systematic review commissioned by WHO found 55 studies. Of them, 42 of 50 in children and all 5 in adults reported at least one link between more sugar and more caries. The data were too varied to pool. Five cohort studies could compare intakes directly, and all five found more caries when free sugars were above 10% of energy than below it. WHO rated that moderate quality evidence. A 2024 review for WHO in children up to 10 years found that 34 of 37 studies linked sugary drinks or foods high in free sugars to caries, and 67.6% of those studies were at serious risk of bias.

How often, and when

Timing carries much of the signal. A 2020 review of 5 cohort studies in young children and pre-adolescents found that eating processed sugary and starchy foods between meals was consistently linked with more caries, while total intake gave mixed results. Few studies fed that review, and foods eaten at meals may protect the teeth, which confounds it. US labeling rules put the same idea into an authorized health claim: frequent between-meal snacks high in sugars and starches can promote tooth decay.

Fluoride changes the size of the link

Fluoride lowers the risk, though it does not remove the sugar link. For children under 5 in higher-risk settings, a 2021 review for the US Preventive Services Task Force found topical fluoride cut the risk of new caries by 20%, a risk ratio of 0.80 (95% CI 0.66 to 0.95) across 12 trials, an absolute difference of 7 percentage points, with no rise in fluorosis. A 2001 review of 36 studies from areas with fluoride found the sugar link much weaker than before. Two studies found a strong relationship, sixteen a moderate one and eighteen a weak one or none. WHO still holds that fluoride reduces and delays caries without fully preventing it, and that decay still progresses where fluoride is used.

Sugar swaps and school programs

In one trial in the 2024 Cochrane review, 113 mothers given xylitol, a sugar alcohol, rather than chlorhexidine had children with 2.39 fewer decayed, missing or filled baby teeth (95% CI 0.68 to 4.10), on low certainty evidence from a single trial. In the EU, sugar-free chewing gum may be labeled as helping reduce tooth demineralisation. A Cochrane review of school programs on toothbrushing and sugar snacking found 4 trials with 2,302 children aged 4 to 12, and only one measured new caries. Three of the four were at high risk of bias, and the authors judged the evidence insufficient.

Who should be careful

Not for everyone. Children who have sugary food or drinks around bedtime, especially preschoolers. A 2018 review of 18 studies in children aged 3 to 16 found a consistent link with caries in every age group, and all 7 studies in preschool children were significant. The review rated the evidence very low quality, and most of the studies were cross-sectional.

For children, the medical guidance is stricter than for adults. The ESPGHAN nutrition committee advises free sugars under 5% of energy for children aged 2 to 18, and probably lower still for infants and toddlers under 2. WHO sets free sugars below 10% of daily energy for adults and children, and ideally below 5%. Free sugars include honey, syrups and fruit juice, and they do not include whole fruit. EFSA advises keeping added and free sugars as low as possible within a nutritionally adequate diet, and it could not set an upper limit.

What expert bodies say

EFSA's 2022 opinion calls dietary sugars a well-established factor in caries at all ages and found no safe threshold. WHO's 2015 guideline draws on the caries evidence for its 10% and 5% limits, and keeps them in place where fluoride is used. ESPGHAN sets the 5% goal for children. US and EU labeling law each allow a claim tied to the sugar and caries link, one about between-meal snacking and one about sugar-free gum.

The practical reading is about frequency as much as amount. Sugar kept to meals, fluoride on the teeth and nothing sweet at bedtime is the pattern the evidence favors. More on sugar itself is on the sugar page.

How we searched

What would change this answer

• Better cohort data on intakes below 5% of energy. That is where the WHO limit is weakest and where a dose response would settle how low is low enough.
• Studies in adults, including decay of exposed roots in older people. Only 5 adult studies made it into the WHO review.
• A randomized trial of cutting free sugar with caries as the outcome. It is unlikely to be run for ethical reasons, which is why this answer will keep resting on cohorts and mechanism.

Sources

1. ev-sgtd-01 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis of randomized controlled trials · n = 782
   We observed a probable 15 per cent reduced risk of caries presence in primary teeth with the intervention (RR 0.85, 95% CI 0.75 to 0.97; 3 trials; 782 participants; moderate-certainty evidence)
   
   Who: pregnant women, new mothers and caregivers of infants in the first year of life, children followed up to six years
   Effect: caries presence in primary teeth RR 0.85 (95% CI 0.75 to 0.97), 3 trials, moderate certainty
   Certainty: Moderate certainty (GRADE); advice covered diet and feeding as a whole, not sugar alone.
   Cochrane Database Syst Rev, 2024 · checked 2026-10-07 · we read the abstract
2. ev-sgtd-02 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis of randomized controlled trials · n = 113
   but we observed there may be a lower mean dmft with xylitol (MD -2.39; 95% CI -4.10 to -0.68; 1 trial, 113 participants; low-certainty evidence)
   
   Who: mothers given xylitol or chlorhexidine treatment, children followed for early childhood caries
   Effect: dmft MD -2.39 (95% CI -4.10 to -0.68), 1 trial, low certainty
   Certainty: Single trial; xylitol is a sugar alcohol used in place of sugar.
   Cochrane Database Syst Rev, 2024 · checked 2026-10-07 · we read the abstract
3. ev-sgtd-03 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis of randomized controlled trials · n = 21 RCTs
   Only one study reported on dental health, with no events.
   
   Who: generally healthy adults in randomized trials of added sugar intake
   Effect: 1 trial reported dental health, 0 events
   Certainty: Trials were short (mean 14 weeks), too short for caries to develop.
   Cochrane Database Syst Rev, 2022 · checked 2026-10-07 · we read the abstract
4. ev-sgtd-04 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized clinical trials · n = 8177
   topical fluoride compared with placebo or no topical fluoride was associated with decreased caries burden (13 trials, n = 5733; mean caries increment [difference in decayed, missing, and filled teeth or surfaces], -0.94 [95% CI, -1.74 to -0.34]) and likelihood of incident caries (12 trials, n = 8177; RR, 0.80 [95% CI, 0.66 to 0.95]; absolute risk difference, -7%) in higher-risk populations or settings, with no increased fluorosis risk.
   
   Who: children younger than 5 years in higher-risk populations or settings
   Effect: incident caries RR 0.80 (95% CI 0.66 to 0.95), 12 trials; caries increment -0.94 (95% CI -1.74 to -0.34), 13 trials; no increase in fluorosis
   Certainty: Higher-risk settings only; education and xylitol evidence was limited.
   JAMA, 2021 · checked 2026-10-07 · we read the abstract
5. ev-sgtd-05 · Meta-analysis or systematic review · Cochrane systematic review of randomized controlled trials · n = 2302
   Only one included study reported the primary outcome of development of caries.
   
   Who: children aged 4 to 12 years in primary school behavioral interventions
   Effect: 1 of 4 trials reported caries; prevented fraction 0.65 (95% CI 0.12 to 1.18) in that trial
   Certainty: Three of four trials at high risk of bias; authors judge evidence insufficient.
   Cochrane Database Syst Rev, 2013 · checked 2026-10-07 · we read the abstract
6. ev-sgtd-06 · Observational data · systematic review of intervention, cohort, population and cross-sectional studies · n = 55 studies
   Of the studies, 42 out of 50 of those in children and 5 out of 5 in adults reported at least one positive association between sugars and caries. There is evidence of moderate quality showing that caries is lower when free-sugars intake is < 10% E.
   
   Who: children and adults in 3 intervention, 8 cohort, 20 population and 24 cross-sectional studies
   Effect: positive association in 42 of 50 child studies and 5 of 5 adult studies; caries lower when free sugars <10% of energy (moderate quality)
   Certainty: GRADE moderate for the <10% cut-off, very low for <5%; data too varied to pool.
   J Dent Res, 2014 · checked 2026-10-07 · we read the abstract
7. ev-sgtd-07 · Observational data · systematic review and meta-analysis of cohort studies · n = 9 cohorts (meta-analysis), 17 in review
   The pooled effect estimate from the meta-analysis yielded an OR of 1.59 and a 95% CI (1.50-1.68), indicating that children who consumed sugar in early childhood were 59% more likely to develop caries compared to those who did not consume sugar.
   
   Who: children under 6 years of age in cohort studies
   Effect: OR 1.59 (95% CI 1.50 to 1.68)
   Certainty: Odds ratio, not risk; authors rate included studies at low risk of bias.
   Braz Oral Res, 2025 · checked 2026-10-07 · we read the abstract
8. ev-sgtd-08 · Observational data · systematic review of prospective cohort studies · n = 5 cohort studies
   The between-meal consumption of processed sugar- and starch-containing foods was consistently found to be associated with greater caries experience.
   
   Who: young children and pre-adolescents in prospective cohort studies
   Effect: between-meal consumption consistently associated with greater caries; total consumption mixed
   Certainty: Few studies; confounding by caries-protective foods eaten at meals.
   Eur J Oral Sci, 2020 · checked 2026-10-07 · we read the abstract
9. ev-sgtd-09 · Observational data · systematic review of observational studies · n = 18 studies
   The studies showed a consistent positive association across the 3 age groups, with all 7 studies on preschool children reporting significant positive associations.
   
   Who: children aged 3 to 16 years in 13 cross-sectional, 4 cohort and 1 case-control study
   Effect: consistent positive association in all 3 age groups; all 7 preschool studies significant; GRADE very low
   Certainty: Very low quality (GRADE); mostly cross-sectional.
   JDR Clin Trans Res, 2018 · checked 2026-10-07 · we read the abstract
10. ev-sgtd-10 · Observational data · systematic review of non-randomized studies · n = 37 studies
    Almost all studies (n = 34) reported positive associations between the consumption of sugar-sweetened beverages or foods high in free sugars and dental caries. However, 67.6% of studies were assessed as having serious risk of bias.
    
    Who: children aged 10 years or younger
    Effect: 34 of 37 studies positive; 67.6% at serious risk of bias
    Certainty: Narrative synthesis; high heterogeneity of exposures.
    Nutr Rev, 2024 · checked 2026-10-07 · we read the abstract
11. ev-sgtd-11 · Observational data · systematic review of observational studies · n = 36 studies
    Results showed that only two papers found a strong relationship between sugar consumption and caries development, sixteen found a moderate relationship, and eighteen found weak-to-no relationship. It was concluded that the relationship between sugar consumption and caries is much weaker in the modern age of fluoride exposure than it used to be.
    
    Who: people in countries with moderate to extensive fluoride exposure
    Effect: strong relationship in 2 studies, moderate in 16, weak to none in 18
    Certainty: Older review (1980 to 2000); WHO 2015 still finds the link where fluoride is used.
    J Dent Educ, 2001 · checked 2026-10-07 · we read the abstract
12. ev-sgtd-12 · Position of an expert body · EFSA scientific opinion based on a systematic review · n = —
    although it is well established that dietary sugars are involved in the development of dental caries at all ages, the available BoE does not allow conclusions on the shape of the relationship between the intake of dietary sugars and risk of dental caries for any age group, or to identify a level of sugars intake at which the risk of dental caries is not increased.
    
    Who: all age groups
    Effect: hazard established; no threshold identified
    Certainty: EFSA reviewed 1 intervention study and 7 prospective cohorts on caries.
    EFSA Journal, 2022, Tolerable upper intake level for dietary sugars (EFSA NDA Panel) · checked 2026-10-07 · we read the fulltext
13. ev-sgtd-13 · Position of an expert body · EFSA scientific opinion based on a systematic review · n = —
    the intake of added and free sugars should be as low as possible in the context of a nutritionally adequate diet
    
    Who: general population of the EU
    Effect: no UL or safe level set; intake as low as possible
    Certainty: Covers caries and chronic metabolic disease together.
    EFSA Journal, 2022, Tolerable upper intake level for dietary sugars (EFSA NDA Panel) · checked 2026-10-07 · we read the fulltext
14. ev-sgtd-14 · Position of an expert body · EFSA scientific opinion based on a systematic review · n = —
    Dietary sugars are metabolised by plaque microorganisms to organic acids which demineralise enamel and dentine, subsequently causing caries. Sucrose is also known to contribute to the formation of dental plaque.
    
    Who: all age groups
    Effect: mechanism: plaque fermentation of sugars to organic acids, enamel demineralisation
    Certainty: Mechanism as summarized by the agency.
    EFSA Journal, 2022, Tolerable upper intake level for dietary sugars (EFSA NDA Panel) · checked 2026-10-07 · we read the fulltext
15. ev-sgtd-15 · Position of an expert body · WHO guideline · n = —
    No RCTs were identified that met the inclusion criteria.
    
    Who: children
    Effect: 0 eligible RCTs; 1 non-randomized intervention study and 50 observational studies
    Certainty: The causal case rests on cohorts, population data and mechanism.
    WHO, 2015, Guideline: sugars intake for adults and children · checked 2026-10-07 · we read the section
16. ev-sgtd-16 · Position of an expert body · WHO guideline · n = 5 cohort studies
    All of these studies reported higher levels of dental caries when the amount of free sugars intake was more than 10% of total energy intake compared with it being less than 10% of total energy intake.
    
    Who: children in longitudinal cohort studies
    Effect: higher caries with free sugars >10% vs <10% of energy in 5 of 5 cohorts
    Certainty: WHO rated this moderate quality evidence.
    WHO, 2015, Guideline: sugars intake for adults and children · checked 2026-10-07 · we read the section
17. ev-sgtd-17 · Position of an expert body · WHO guideline · n = —
    In both adults and children, WHO recommends reducing the intake of free sugars to less than 10% of total energy intake2 (strong recommendation). WHO suggests a further reduction of the intake of free sugars to below 5% of total energy intake (conditional recommendation3).
    
    Who: adults and children
    Effect: free sugars <10% of energy (strong), <5% (conditional)
    Certainty: Upper limit for intake; the 5% figure rests on very low quality ecological caries data.
    WHO, 2015, Guideline: sugars intake for adults and children · checked 2026-10-07 · we read the section
18. ev-sgtd-18 · Position of an expert body · WHO guideline · n = —
    Although exposure to fluoride reduces dental caries at a given age, and delays the onset of the cavitation process, it does not completely prevent dental caries, and dental caries still progresses in populations exposed to fluoride
    
    Who: populations exposed to fluoride
    Effect: fluoride lowers but does not remove sugar-driven caries
    Certainty: Reason WHO keeps the sugar limit where fluoride is in use.
    WHO, 2015, Guideline: sugars intake for adults and children · checked 2026-10-07 · we read the section
19. ev-sgtd-19 · Position of an expert body · position paper · n = —
    Intake of free sugars should be reduced and minimised with a desirable goal of <5% energy intake in children and adolescents aged ≥2 to 18 years. Intake should probably be even lower in infants and toddlers <2 years.
    
    Who: children and adolescents aged 2 to 18 years; infants and toddlers under 2 years
    Effect: free sugars goal <5% of energy from age 2; lower under 2
    Certainty: Position of a medical society (T3-level context) published in a peer-reviewed journal.
    J Pediatr Gastroenterol Nutr, 2017 · checked 2026-10-07 · we read the abstract
20. ev-sgtd-20 · Position of an expert body · federal regulation · n = —
    (i) Frequent eating of foods high in sugars and starches as between-meal snacks can promote tooth decay. The sugar alcohol [name, optional] used to sweeten this food may reduce the risk of dental caries.
    
    Who: US food labels
    Effect: authorized model health claim text
    Certainty: Authorized for noncariogenic sweeteners; the claim is about snacking frequency.
    21 CFR 101.80, Health claims: dietary noncariogenic carbohydrate sweeteners and dental caries · checked 2026-10-07 · we read the section
21. ev-sgtd-21 · Position of an expert body · EU health claim register entry · n = —
    POL-HC-6245 Sugar-free chewing gum Sugar-free chewing gum helps reduce tooth demineralisation. Tooth demineralisation is a risk factor in the development of dental caries. -/- Authorised
    
    Who: EU food labels
    Effect: claim status: Authorized
    Certainty: Conditions of use are in Regulation (EU) 432/2012 and are not quoted here.
    EU Register on nutrition and health claims (European Commission) · checked 2026-10-07 · we read the dataset