A new systematic review and meta-analysis published in the journal Nutrition Reviews reminds us that vitamin D may prevent dental caries.
The study, authored by Professor Philippe P Hujoel, PhD, DDS, of the School of Dentistry of the University of Washington, examined 24 controlled clinical trials encompassing 2,827 children.
Between World War I and World War II, soon after vitamin D was discovered, researchers extensively examined if vitamin D could help prevent dental caries. Vitamin D had been hypothesized as a means to prevent dental caries by a variety of mechanisms, including:
- Helps better tooth development
- Helps better dentinal mineralization responses to caries throughout life
- Has a topical fluoride-like effect
- Changes the amount or biochemical composition of saliva
- Modulates caries activity through immunological factors
However, in 1945, the American Dental Association released a statement that said vitamin D was not beneficial in the prevention of caries, contrary to statements released by the American Medical Association around the same time. Since then, interest in the area has largely been forgotten. For example, the 2011 IOM report does not even mention or examine any relationship between dental caries and vitamin D.
Here, Professor Hujoel reexamined the issue using more current meta-analysis techniques. In this meta-analysis, trials were included in the meta-analysis if they met the following criteria: used dietary vitamin D or UV radiation, reported incident caries and follow-up time, included a concurrent control group, administered vitamin D for the purpose of prevention and that it was a prospective trial design (as opposed to retrospective).
Professor Hujoel found 24 trials that met these criteria. Within these 24 trials, there were 38 arms using some type of vitamin D treatment, seventeen that used D3 (median dose 800 IU/day), fifteen that used D2 (median dose 3,750 IU/day), and six UV radiation therapies. For the various treatment arms, Hujoel found the following reduced risks for caries:
- 74% reduction in caries in UV radiation arms (RR = 0.36; 95% CI, 0.17–0.78)
- 49% reduction in caries in vitamin D3 arms (RR =0.51; 95% CI, 0.40–0.65)
- 36% reduction in caries in vitamin D2 arms (RR = 0.64; 95% CI, 0.48–0.86)
When pooled all together, there was a 47% reduced risk in getting caries in the vitamin D groups versus the control groups (RR=0.53; 95% Cl, 0.43–0.65).
Since most of these trials took place in the 1920s through the 40s, many trials lacked examiner blinding and just over half lacked administration of a placebo, so there is a bit of room for bias in results of individual trials. However, that being said, the studies that more closely meet the standards of today’s randomized controlled trials showed the most benefit in vitamin D.
The author concludes:
“In summary, this systematic review of controlled clinical trials suggests that vitamin D exposures in early life may play a role in caries prevention. This promising evidence base may be relevant to current challenges in improving health, as vitamin D levels in the US population are decreasing and dental caries among US children is increasing.”
We’ll also add that perhaps this will reopen the door for more research in dental caries and vitamin D, using more current methodology, after 60-plus years of the topic largely being ignored.