Dr Philippe P Hujoel of the Department of Oral Health Sciences at the University of Washington just published a remarkable review and meta-analysis of the role vitamin D plays in preventing dental cavities. Brant Cebulla also blogs on the study here.
He identified, believe it or not, twenty-four controlled clinical trials that studied a total of 2,827 children. All the selected papers included a control group, were prospective, and reported number and severity of cavities during a specified follow up period. However, virtually all of these studies were conducted in the 1930s and 40s, so most lack randomization or double blind procedures.
Still, after the studies in the 1930s and 40s, the American Medical Association (AMA) concluded in 1946 that vitamin D was beneficial in preventing dental caries.
Council on Pharmacy and Chemistry. New and Non-official Remedies. Chicago: American Medical Association; 1946:610
If you remember, Vitamin D Council board member, Dr William Grant, published an excellent review in 2011, not only reviewing many of the same studies, but discovering as well that UV radiation from the sun is associated with fewer cavities.
Dr Hujoel’s meta-analysis found that the pooled data indicated that vitamin D and UV radiation halved the incidence of dental cavities. UV radiation worked the best, followed by D3 then D2. However, while the dose of D2 was substantial (averaging 3,750 IU/day), the dose of D3 was not (averaging 800 IU/day). The effect vitamin D had on reducing caries in the meta-analysis were highly significant (P<.0001).
In the most recent research on the subject, a group from Canada discovered that lower vitamin D levels were associated with severe dental cavities.
Why have these many controlled trials been ignored for so long? My only guess is that lots of the controlled trials prior to the 1940s were forgotten and ignored after the many cases of toxicity and deaths in the 1940s because of the regrettable trend of supplementing with millions of IUs/week. Physicians and scientists’ enthusiasm may have turned to fear, without putting the issue into proper dosage perspective. However, as far as I know, the AMA never retracted their 1946 statement, meaning the AMA still endorses the use of vitamin D to prevent cavities.
Prevention of cavities seems to be another great reason to make sure children, and adults for that matter, be sufficient in vitamin D and consider both supplementing and UV exposure as viable options. The Vitamin D Council recommends children supplement with 1000 IU/day per 25 lbs of body weight, and adults supplement with 5000 IU/day.