Tea is often treated as a healthy choice for your mouth. But this study found a genetic clue pointing in the opposite direction for gum disease—while finding no link with cavities. Oral conditions affect 3.9 billion people worldwide, with dental caries, periodontitis, and tooth loss among the most common issues.

These problems can affect appearance, chewing, and social development. Periodontitis is a chronic inflammatory disease caused by bacteria in the tissues around the teeth. It can lead to bad breath and loose teeth, and it is connected with some diseases elsewhere in the body.

Tea has a divided reputation. On one hand, tea contains substances that can inhibit harmful mouth bacteria, and tea can increase fluoride consumption, which helps prevent dental caries. On the other hand, tea has been regarded as a risk factor for caries because of its erosive effect on enamel, while surveys have suggested that tea might harm periodontitis.

Until now, the causal link has remained controversial. So the study used a two-sample Mendelian randomization analysis, based on genome-wide association studies, to explore whether tea intake was related to the risks of dental caries and periodontitis. A clearer understanding of the relationship between tea intake and these oral diseases could provide new insights into prevention.

When several outcomes were tested, a Bonferroni adjustment made the significance threshold stricter. A result below the adjusted threshold counted as statistically significant. A result below zero point zero five but not below that stricter threshold was treated as suggestive instead.

The main result pointed in two directions: higher tea intake was associated with fewer natural teeth and with the presence of periodontitis. Tea intake had no association with measures of dental caries. The periodontitis link remained statistically significant after the stricter correction for multiple comparisons, while the association with the number of natural teeth did not.

The estimates across many inherited markers mostly cluster around no clear link between tea intake and either tooth decay or gum disease. The fitted lines stay close to level, so this analysis does not provide strong evidence that drinking more tea changes either risk. Here is the important complication.

The causal association between tea intake and periodontitis became weaker after adjusting for years of schooling and average total household income before tax. That weakening indicated that the link might be partly mediated by socioeconomic factors, rather than being caused by tea alone.

The genetic approach can reduce some hidden influences and avoid the problem of reverse causality compared with traditional cross-section studies. But the research objects were all European, which may limit how far the results can be applied to other populations.

The study also lacked enough information to tell whether tooth loss differed by cause, such as caries, periodontitis, or trauma. More explicit mechanisms explaining how tea might act on these diseases still need study. The study found that genetically predicted higher tea intake was linked with greater periodontitis risk, but that link weakened after accounting for education and household income.

It was not linked with caries.