BACKGROUND: Here, we aimed to investigate the therapeutic effects of extract on serum brain-derived neurotrophic factor (BDNF) and depression score in patients with depression. MATERIALS AND METHODS: This clinical trial was performed in 2021 in the hospitals of military forces in Tehran on 52 male patients with major depressive disorder treated with sertraline. We used the Depression, Anxiety, and Stress Scale-21 Items (DASS-21) questionnaire to assess the patients. Serum BDNF levels were measured by the enzyme-linked immunosorbent assay. Patients were then divided into two groups receiving 1000 mg oil extract, daily, and placebo. Both groups received sertraline for at least 3 months. DASS-21 questionnaire and serum BDNF levels were measured after 10 weeks. RESULTS: After treatments, we observed significantly decreased DASS-21 score (-11.24 ± 5.69) in the intervention group ( < 0.001) and placebo (-2.72 ± 6.19, = 0.032), but patients in the intervention group had significantly lower scores (50.1 ± 6.8 vs. 58.2 ± 5.6, respectively, < 0.001). Furthermore, patients in the intervention group had significantly decreased depression score (-5.5 ± 2.47, < 0.001) and lower scores compared to the placebo ( < 0.001) (18.6 ± 2.7 vs. 23.4 ± 2.1 in intervention and placebo, respectively). We also observed significantly increased BDNF levels in the intervention group after the treatments (6.08 ± 3.76, < 0.001) compared to the placebo group (29.4 ± 3.6 vs. 24.9 ± 2.1, < 0.001). Serum BDNF levels had also significant reverse correlations with DASS-21 score ( = -0.35, = 0.011) and depression score ( = -0.45, = 0.001). CONCLUSION: The use of resulted in decreased depression score and increase in serum BDNF levels that indicate the importance and efficacy of this drug.