The primary risk factors for dental caries are eating sweets and not brushing the teeth.
Sunlight exposure and risk of dental caries
There are a number of U.S. studies reporting on the relationship of solar ultraviolet-B (UVB) light and dental caries. These studies stretch over a long period of time:
- During the Civil War, men living in the Northeast were rejected from the draft at a higher rate than men living to the south. The Northeast has less sunshine than other areas.
- In the 1930s, the number of dental caries among adolescent males was plotted on a map. Dental caries rates were lowest in the Southwest and highest in the Northeast and Northwest. UVB light triggers vitamin D, which increases calcium absorption from food and helps generate a protein that fights bacteria that cause caries.
- In the mid-1900s, men enlisting in the armed forces from Texas and nearby states had the fewest caries. The highest number of caries were noted in men living in the Northeast and Northwest. Dental caries rates in the northern Rocky Mountain states were somewhat lower than dental caries rates in states to the east or west. This was probably due to higher surface elevation and more UVB.
- In the 1950s, schoolchildren living in the sunnier inland counties of Oregon had fewer caries than those living in counties with more fog (mostly coastal regions). These studies ruled out other risk factors for caries such as eating foods with sugar or having fluoride in the water.
Vitamin D and dental caries
Vitamin D levels
Other studies reported on vitamin D and dental caries in the 1920s and 1930s:
- In England, vitamin D stimulated the calcification of dogs’ teeth. (Calcification is the build-up of hard plaque.) Vitamin D was also beneficial for dental caries in children.
- In New York, dental caries were prevented in children who took 800 international units (IU) (20 mcg)/day of vitamin D.
How vitamin D works
To reduce the risk and severity of dental caries, vitamin D produces cathelicidin and defensins. These proteins have antibacterial effects to fight bacteria that cause dental caries. They may also neutralize toxic byproducts.
Having vitamin D blood levels above 30-40 ng/mL (75-100 nmol/L) may help reduce the risk of dental caries. To reach these levels one must take 1000-5000 IU/day of vitamin D3 (cholecalciferol).
Since there is considerable person-to-person difference in response to vitamin D supplementation, it is worthwhile to measure vitamin D levels after supplementing for several months.
Vitamin D and calcium
Calcium is also important for preventing dental caries. Green leafy vegetables and milk are good sources of calcium. Supplements can be taken if not enough calcium is not obtained from food.
Vitamin D and calcium cannot reverse dental caries. Caries must be treated by a dentist. However, vitamin D and calcium can reduce the likelihood that additional caries will develop.
This evidence summary was written by:
William B. Grant, Ph.D.
Sunlight, Nutrition, and Health Research Center (SUNARC)
P.O. Box 641603
San Francisco, CA 94164-1603, USA
Complete bibliography of research used in this summary
The research we have cited in our summary is listed below, with links to PubMed abstracts and full-text for those who wish to explore further.
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