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Background: Increased inflammation and heightened physiological stress reactivity have been associated with pathophysiology of depressive symptoms. The underlying biological mechanisms by which inflammation and stress may influence neurogenesis are changes in the kynurenine (KYN) pathway, which is activated under stress. Supplementation with n -3 polyunsaturated fatty acids ( n -3 PUFAs) has anti-inflammatory properties and can increase stress resilience. Whether n -3 PUFAs alter KYN stress response is unknown. Objectives: This placebo-controlled study investigated the effect of n -3 PUFAs on KYN metabolism, inflammation, depressive symptoms, and mood. Moreover, stress-induced changes following a laboratory stressor have been assessed. Methods: In this placebo-controlled study, 47 healthy male adults received either 4 g n -3 PUFAs per day (Omega-3 group) or a placebo (Placebo group) for 12 weeks. Results: A significant group-by-time interaction was found for the inflammatory markers gp130 (F = 7.07, p = 0.011), IL-6R alpha (F = 10.33, p = 0.003), and TNF_RI (F= 10.92, p = 0.002). No significant group-by-time interactions were found for KYN metabolites, depressive symptoms, and mood (except for Hedonic tone (F = 6.50, p = 0.014)), nor for stress-induced changes in KYN metabolites and mood following a laboratory stressor. Conclusions: Overall, increased n -3 PUFA levels in healthy men ameliorate inflammatory markers but do not ameliorate KYN metabolism, depressive symptoms, mood, or KYN metabolism and mood following a stress induction. This study was registered at ClinicalTrials.gov with the identifier NCT05520437 (30/08/2022 first trial registration).

Background: The prevalence of depressive symptoms (DS) among physically active individuals tends to be lower compared to sedentary controls. This association seems to be moderated by gender and level of physical activity (PA). The objective of this meta-analysis was to assess the relationship between PA and DS in males based on different levels of PA., Methods: A systematic review and meta-analyses were conducted following the PRISMA Statement for Systematic Reviews. The literature search was conducted from January 1, 2003 to February 20, 2023. Cross-sectional and cohort studies including male participants aged 18 years or older were included in the analysis. Evidence from selected studies was synthesised as differences between odds ratios to assess whether DS were exhibited among those who were engaged in low, moderate, and high PA via random-effects meta-analyses. This study is registered on PROSPERO, number CRD42023417219., Results: Out of 1737 records identified, 5 eligible studies were included with a total of 35,811 participants. Results indicated significant effects of moderate PA on DS (OR = 0.68; 95 % C.I. 0.50-0.93). No effect of low and high PA on DS was found (OR = 0.79; 95 % C.I. 0.52-1.20 and OR = 0.78; 95 % C.I. 0.47-1.30)., Conclusion: Males who engage in moderate PA present lower prevalence of DS compared to no-PA reference. Such associations were not found for low or high PA. Hence, mental health benefits of PA could possibly be achieved at appropriate levels of PA. High heterogeneity between the studies should be considered when interpreting the results., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)