Cross-Sectional and Prospective Associations of Carbonated Soft Drink Consumption, BDNF Val66Met Polymorphism, and Psychological Distress

Background/Objectives: Few prospective studies have investigated the association between carbonated soft drink (CSD) consumption and psychological distress (PD) among adults. The current study aimed to examine this association according to the BDNF Val66Met polymorphism and to conduct comparable analyses for coffee and green tea consumption. Methods: Cross-sectional data (n = 6244) and 6-year prospective data (n = 1984) comprising participants aged 43–74 years were analyzed. PD was defined as a Psychosocial Wellbeing Index (PWI) score ≥ 27. Beverage consumption was assessed using a food frequency questionnaire. Modified Poisson regression was employed to estimate multivariable prevalence ratios or risk ratios (RRs) and 95% confidence intervals (CIs) for PD. Results: In cross-sectional data, green tea consumption was inversely associated with PD prevalence in the overall study population (p for trend < 0.05), and its dose–response relationship was observed exclusively among BDNF Met allele (CT and TT) carriers. In 6-year prospective data, CSD consumption was positively associated with PD risk among BDNF Met allele carriers only (p for trend < 0.01); multivariable RR (95% CI) for PD among BDNF Met allele carriers was 1.94 (1.21, 3.10)—(95% CI: 1.09, 3.44) after further applying the Bonferroni correction—for those who consumed ≥ 1 cup/week compared with non-consumers. No prospective association was observed for coffee and green tea consumption in the overall study population and genotype-specific analyses. Conclusions: CSD consumption was associated with increased PD risk among individuals carrying the BDNF Met allele, which is known to be associated with various stress-related psychological conditions. These findings suggest that CSD consumption may be particularly harmful to individuals with specific genetic factors.