Vitamin D for Dental Caries

Does vitamin D prevent cavities? Not proven. A 2013 meta-analysis of 24 controlled trials in 2,827 children found a pooled relative rate of 0.53 (95% CI 0.43 to 0.65) with supplemental vitamin D. But 22 of the 24 trials predated modern trial design, the results were highly heterogeneous (P < 0.0001) and publication bias was significant (P < 0.001), so the author reached only a low-certainty conclusion that vitamin D may reduce caries.

Recent studies do not back that up, though none tests vitamin D against no vitamin D. Children whose mothers took 2,400 IU of vitamin D3 a day in pregnancy, on top of 400 IU, had fewer enamel defects at age 6 than those on 400 IU alone, but no difference in caries. In a trial of infants given 400 or 1,200 IU a day for two years, oral health at age 6 to 7 did not differ between doses. Low vitamin D status does go with more cavities in observational studies, yet a genetic analysis found little evidence of a causal effect. Vitamin D still matters for bone health (see the vitamin D page), but cavity prevention is a job for fluoride and dental care (see dental caries).

Early fetal stages of tooth development are vitamin D-dependent, and NIH lists dental abnormalities among the features of severe rickets, the childhood disease caused by deficiency. A 2024 narrative review proposes that deficiency may cause enamel defects before birth and, through childhood, is accompanied by weaker antibacterial peptide activity, less saliva and less calcium in saliva.

In 85 Swedish children, vitamin D status at age 6 was positively associated with saliva levels of LL37, an innate immunity peptide, but unrelated to enamel defects.

These are explanations for an association, drawn from a narrative review and small human studies. None shows that giving extra vitamin D to a child who already has enough changes enamel, saliva or cavities. The Swedish study measured a peptide, not cavities.

Even the enamel link is not consistent. In the Danish Odense cohort, pregnancy and cord blood vitamin D status was not associated with hypomineralization of second primary molars in 4-year-olds (54.7% had it), in a population with relatively high vitamin D levels.

No trial has set a vitamin D dose for preventing cavities, and the 2013 meta-analysis abstract gives no dose. The recent trials were designed for other purposes: the pregnancy trial gave 2,400 IU a day from week 24 to a week after birth on top of the 400 IU all women received, and the infancy trial compared 10 and 30 mcg (400 and 1,200 IU) of vitamin D3 a day from 2 weeks to 2 years.

In the Swedish study, 6-year-olds took 25, 10 or 2 mcg (1,000, 400 or 80 IU) a day for 3 months. For general health, NIH ODS lists 400 IU a day for infants and 600 IU a day from age 1 to 18; 1 mcg equals 40 IU.

The 2013 meta-analysis pooled 24 controlled trials in 2,827 children. Twenty-two predated modern trial design; among those older trials, 2 reported pseudo-randomization, 4 blinding and 8 placebos. The pooled relative rate was 0.53 (95% CI 0.43 to 0.65), with significant heterogeneity and publication bias. It found no robust difference between vitamin D2, vitamin D3 and ultraviolet radiation (P = 0.22).

A separate 1989 Canadian school study (the meta-analysis abstract does not list its trials) tested ultraviolet-containing lighting. In a fluoridated community, 102 children entering grade 5 spent 22 months in classrooms with full-spectrum lighting or in control classrooms; 83 finished. DMFS (decayed, missing and filled surfaces) rose from 2.67 to 3.23 with the light and from 2.32 to 4.46 in controls (p < 0.001, excluding sticky fissures). It tested lighting, not a supplement, and the abstract reports no vitamin D levels.

The Copenhagen COPSAC2010 trial gave 623 pregnant women 2,400 IU of vitamin D3 a day or placebo, all on top of 400 IU. At age 6, 496 of 588 children were examined. Enamel defects in permanent teeth were 15.1% versus 27.5% (odds ratio 0.47, 95% CI 0.27 to 0.81) and in baby teeth 8.6% versus 15.9% (odds ratio 0.50, 95% CI 0.28 to 0.87). There was no association between supplementation and caries. This was a post hoc analysis of a trial designed for asthma.

A follow-up of an infant trial (975 infants given 10 or 30 mcg a day for two years) examined 123 children at 6 to 7. Enamel defects were found in 39% of the 10 mcg group and 53% of the 30 mcg group (p = 0.104); 94% were vitamin D sufficient, 88% were caries-free, and no association with oral health was found. With so few cavities, the trial had little room to show a difference. Neither trial compared vitamin D with no vitamin D: the pregnancy trial compared a higher dose with a standard dose, and the infant trial compared two doses.

A 2023 meta-analysis of 13 observational studies found that children with vitamin D deficiency had a 22% higher caries risk (relative risk 1.22, 95% CI 1.18 to 1.25), and a 2024 meta-analysis of 10 studies found lower 25(OH)D in children with early childhood caries, with higher odds at 50 to 75 than above 75 nmol/L (odds ratio 1.42). In a Canadian national survey of 1,017 children aged 6 to 11, caries went with 25(OH)D below 75 nmol/L, but also with lower household education, not brushing twice daily and yearly dental visits.

For pregnancy, a meta-analysis of 12 studies (11,021 participants) found caries in 44% of children of mothers with deficiency versus 25% without (odds ratio 1.35), with heterogeneity of 86.6%. A Chinese cohort of 4,109 mother-child pairs found higher maternal 25(OH)D linked to lower odds of early childhood caries (odds ratio 0.98 per unit in the first and second trimesters). A 2023 review of seven studies found odds ratios from 0.68 to 2.15, with only three significant, and called the findings inconsistent.

Two analyses suggest not much. In Mendelian randomization of 5,545 English children, the odds ratio for caries per 10 nmol/L higher 25(OH)D was 0.93 (95% CI 0.83 to 1.05; P = 0.26); the authors said estimates were imprecise. In Rotterdam's Generation R cohort (5,257 children), severe deficiency went with caries (odds ratio about 1.6), but children genetically predisposed to lower 25(OH)D did not have more caries. The authors did not recommend vitamin D supplementation to prevent caries.

A cohort of 406 children found less restorative treatment in baby teeth with a full year of fluoride/vitamin D tablets, but the tablets contained fluoride and brushing habits were not recorded, so it cannot be credited to vitamin D.

We found no modern randomized trial that gave vitamin D to children and counted new cavities as its main outcome, and none in adults. The 75 nmol/L target in the observational papers comes from subgroup analyses; NIH ODS notes that the Food and Nutrition Board found even serum levels of about 75 to 120 nmol/L associated with more all-cause mortality, some cancers, cardiovascular events, and falls and fractures in older adults, so a dental target should not drive high doses.

Until a trial tests supplementation against cavities directly, the honest summary is: keep vitamin D adequate, expect little for teeth, and rely on fluoride and dental care.

The dental studies' abstracts do not report side effects. For safety, NIH ODS says vitamin D toxicity causes hypercalcemia (high blood calcium), hypercalciuria and high serum 25(OH)D, with nausea, vomiting, weakness, excessive thirst, dehydration and kidney stones, and in extreme cases kidney failure, calcification of soft tissues and cardiac arrhythmias. It is almost always caused by supplements, including manufacturing errors and excessive or incorrectly prescribed doses.

ODS says toxicity is unlikely below 10,000 IU a day, but the Food and Nutrition Board noted that intakes below the upper limits might still have adverse effects over time. The upper limits are lower for children: 1,000 IU for 0 to 6 months, 1,500 IU for 7 to 12 months, 2,500 IU for ages 1 to 3, 3,000 IU for 4 to 8 and 4,000 IU from 9 years, including in pregnancy and lactation.

The dental studies did not test drug interactions. NIH ODS names orlistat, statins, steroids and thiazide diuretics as medicines that may interact with vitamin D, and notes that taking calcium and vitamin D supplements together may raise the risk of certain adverse effects. The most practical risk here is substitution: using vitamin D in place of fluoride care.