Influence of omega-3 fatty acids on post-traumatic stress disorder: prospective cohort study and Mendelian randomisation findings

Background and Objectives: Omega-3 fatty acids have positive effects on mental health. This study aimed to explore the association between plasma omega-3 fatty acid levels and the risk of post-traumatic stress disorder (PTSD). Methods: This study explored the association between plasma omega-3 fatty acid levels and risk of developing PTSD. In total, 82,391 adults from the UK Biobank were included in this study. PTSD screening was performed using a PCL-6 score greater than 13, based on responses to the online mental health questionnaire. Multivariate logistic regression analyses were performed to evaluate the association between omega-3 fatty acid levels and the risk of PTSD. Additionally, a two-sample bidirectional Mendelian randomisation (MR) analysis was used to investigate potential causal relationships. Results: A significant association was found between high omega-3 fatty acid levels and a lower risk of PTSD. For each 1 unit increase in omega-3 fatty acids, the adjusted odds ratio (OR) was 0.75 (p = 9.05E-05); for each 1% increase in total fatty acids, the adjusted OR was 0.95 (p = 4.30E-07). Among the population that has experienced catastrophic traumatic exposure, the results remained consistent. MR analysis indicated that high omega-3 levels and omega-3/total fatty acid ratios were causally linked to a reduced risk of PTSD (per 1 unit increase, OR = 0.99; p = .029; per 1% increase, OR = 0.98; p = .037). Conversely, PTSD was causally associated with lower omega-3 levels (beta = −0.203, p = 2.12E-05) and a lower omega-3/total fatty acids ratio (beta = −0.266, p = 1.52E-07). Subgroup analyses revealed that females might benefit more significantly (OR = 0.64, p = 3.59E-07; p-interaction = .010). Conclusions: This study suggests a negative association between PTSD and omega-3 fatty acids, indicating that omega-3 supplementation may be an effective preventive and therapeutic strategy for PTSD. A significant link exists between omega-3 fatty acids and reduced risk of PTSD.Notable sex differences were observed, with females showing a stronger association between omega-3 levels and reduced PTSD risk in observational analyses.The findings emphasise the role of dietary interventions in preventing and treating PTSD. A significant link exists between omega-3 fatty acids and reduced risk of PTSD. Notable sex differences were observed, with females showing a stronger association between omega-3 levels and reduced PTSD risk in observational analyses. The findings emphasise the role of dietary interventions in preventing and treating PTSD.