Associations of dietary and drinking water habits with number of natural teeth: a longitudinal study in the Chinese elderly population

BACKGROUND: The relationship between dietary and drinking water habits and oral health are still unclear. We aimed at evaluating the association of dietary and drinking water habits with number of teeth in the elderly adults. METHODS: We conducted a longitudinal study based on the Chinese Longitudinal Healthy Longevity Survey from 1998 to 2018. The data of dietary and drinking water habits at baseline were collected using a questionnaire. The number of teeth at baseline and follow-up was collected for each subject. We used the linear mixed-effect model to analyze the associations of dietary habits and drinking water sources with tooth number. RESULTS: Among 19,896 participants at baseline, the mean age of the participants was 83.87 years, with the average number of natural teeth of 9.37, 8.26, 8.38, 8.68, 4.05, 1.92, 1.12, 2.20 for the first to eighth waves of survey. Compared with subjects drinking tap water, 1.036 (95 % CI: -1.206, -0.865), 0.880 (95 % CI: -1.122, -0.637) and 1.331 (95 % CI: -1.715, -0.947) fewer natural teeth were reported for those drinking well, surface water and spring at baseline survey. Compared with participants with rice intake as the staple food, those with wheat intake (β = -0.684; 95 % CI: -0.865, -0.503) tended to have fewer natural teeth. Compared with participants with fresh fruit intake almost every day, those with quite often intake of fresh fruit tended to have fewer teeth with a significant dose-response trend (P(trend) <0.001). Similar decreased trend for number of teeth was also indicated for increased frequency of vegetable intake (P(trend) <0.001). Fewer number of teeth was found for subjects with less frequency of meat and fish intakes. CONCLUSIONS: The study suggested that drinking well, surface water, and spring, intakes of wheat as staple food, as well as less frequency of fresh fruit, vegetable, meat and fish intakes were associated with significantly fewer number of teeth in the Chinese elderly population. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12877-021-02473-7.