Prospective Associations Between Salivary Biomarkers of Inflammation and Body Mass Index in Adolescents.

Background: Childhood and adolescent obesity, which affects nearly 1 in 5 youth in the US, presents a pressing public health concern. Obesity is linked to chronic low-grade inflammation, which exacerbates comorbidities. Noninvasive tools are needed to monitor obesity-related inflammation and assess weight-management interventions in children and adolescents.

Objective: This study investigated the associations between Body Mass Index z-score (BMIz) and salivary biomarkers: C-reactive protein (CRP), cytokines interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α.

Methods: A sample of 280 adolescents (Mage = 12.1 years, SD = 0.44) was followed for 2 years (3 time points) from 2019 to 2021. An autoregressive cross-lagged path model was used to examine the prospective relationships between BMIz and salivary biomarkers.

Results: Findings indicated a bidirectional relationship between BMIz and salivary CRP levels, suggesting a feed-forward cycle in which excessive weight gain and inflammation mutually amplify each other. Salivary cytokines were not associated with BMIz.

Conclusions: This study underscores the utility of salivary CRP as a noninvasive biomarker for obesity-related inflammation. Monitoring salivary CRP levels could aid in targeting interventions to prevent obesity-related complications early in life.