Investigating the relationship between water fluoride level and anthropometric parameters and blood pressure in adults of Zarand and Sarbisheh cities

Drinking water is the main source of fluoride, which prevents dental caries at recommended levels, while high intake has been linked to adverse outcomes, including noncommunicable diseases. This cross-sectional study was conducted in 2023 on 600 adults aged 18–75 years residing in urban and rural areas of Zarand and Sarbisheh, Iran. Demographic characteristics and determinants of fluoride exposure were collected using a structured questionnaire. Anthropometric measurements, including body mass index (BMI) and waist circumference (WC), as well as blood pressure parameters, including systolic blood pressure (BP) and diastolic blood pressure (DBP), were measured through physical examinations. Drinking water samples were obtained from 43 villages and 4 cities. Simple linear regression and generalized linear model–based tree (GLM-tree) analyses were applied to assess the associations while accounting for potential confounding and moderating factors. The mean age of participants was 40.27 ± 14.54 years, and 68.8% were female. The mean fluoride was 1.06 ± 0.45 mg/L in Zarand and 0.51 ± 0.18 mg/L in Sarbisheh. After adjustment for confounding variables, fluoride exposure at low to moderate levels (0.5–1.5 mg/L) was positively associated with BMI and negatively associated with DBP (P < 0.05). In contrast, high fluoride exposure (> 1.5 mg/L) showed a positive association with WC (P < 0.001). GLM-tree analysis showed that health, lifestyle, and water composition factors moderated the associations between fluoride exposure and anthropometric and blood pressure measures. Overall, the results suggest a possible association between drinking water fluoride levels within recommended standards and anthropometric indicators.