Can Vitamin D Protect Your Oral Health?

New Genetic Evidence Links Vitamin D to Lower Risk of Certain Oral Diseases

Why Vitamin D Matters for the Mouth

Vitamin D is widely known for its role in bone health, but scientists are increasingly interested in its influence on the immune system and inflammation. In recent years, many observational studies have suggested that people with low vitamin D levels may be more prone to oral health problems—from gum disease to oral cancer.

However, these studies often face a major challenge: it is difficult to know whether low vitamin D causes oral disease, or whether illness and lifestyle changes (such as avoiding sunlight) lead to lower vitamin D levels. To answer this question more clearly, researchers have turned to genetic approaches.

What Did the Researchers Do?

In a 2025 study published in Medicine, Shi and colleagues used a method called Mendelian randomization—a genetic approach that works like a natural randomized trial.

Instead of measuring vitamin D directly, the researchers analyzed genetic variants that are known to influence blood levels of 25-hydroxyvitamin D, the standard marker of vitamin D status. Because genes are fixed at birth, this method helps reduce bias from lifestyle factors and reverse causation.

Using large-scale genetic data from European populations, the team examined whether genetically higher vitamin D levels were linked to a range of oral diseases, including:

• Perioral dermatitis

• Oral, lip, and pharyngeal cancers

• Periodontitis (gum disease)

• Oral lichen planus

• Other disorders of the oral cavity and jaws

They also tested the reverse question: could oral diseases themselves influence vitamin D levels?

Key Findings: Protection for Some, Not All

The results showed a clear pattern for certain conditions:

• Lower risk of perioral dermatitis

  People with genetically higher vitamin D levels had a significantly reduced risk of developing perioral dermatitis, a chronic inflammatory skin condition around the mouth.

• Lower risk of oral and pharyngeal cancers

  Higher vitamin D levels were also linked to a reduced risk of cancers affecting the lip, oral cavity, and pharynx. Although some statistical estimates were borderline, the overall direction of results consistently suggested a protective effect.

• No strong link with most other oral diseases

  For conditions such as acute or chronic periodontitis, benign oral tumors, oral cysts, trigeminal neuralgia, and cleft lip or palate, the study did not find convincing evidence that vitamin D levels played a causal role.

Does Oral Disease Lower Vitamin D Levels?

When the researchers looked in the opposite direction, they found little evidence that oral diseases cause changes in vitamin D levels. A small association was seen with oral lichen planus, but the effect was extremely weak and disappeared after stricter statistical correction. Overall, this suggests that reverse causation is unlikely.

Why Are These Findings Important?

This study strengthens the idea that vitamin D may actively help protect against specific oral inflammatory conditions and oral cancers, rather than being a simple marker of general health. Vitamin D’s known roles in immune regulation, inflammation control, and cell growth may help explain these effects.

At the same time, the findings are a reminder that vitamin D is not a universal solution for all oral diseases. Its benefits appear to be selective and disease-specific.

What Should We Take Away?

The study provides strong genetic evidence that maintaining adequate vitamin D levels could play a protective role against perioral dermatitis and certain oral cancers. While this does not yet justify vitamin D supplements as a routine dental therapy, it highlights vitamin D as a promising factor in oral disease prevention—especially for high-risk groups.

Future research, including clinical trials and studies in non-European populations, will be crucial to translate these findings into clear public health and dental care recommendations.

Original Article Reference

Shi Y, Li X, Chen B, Wang Y, Bai G.

Vitamin D and oral disease relationships: Insights from a bidirectional Mendelian randomization investigation.

Medicine. 2025;104(47):e46097.

DOI: 10.1097/MD.0000000000046097