Fig. 3

95% confidence interval bars for change in BDI-II scores by study arm and period. The calculated 95% confidence intervals (CI) for the mean difference in the change in BDI-II scores between the two intervention groups overlapped substantially after 4 weeks (Fish oil (N = 92). 95% CI − 12.3 to − 9.3; soybean oil (N = 98), 95% CI − 12.3 to − 10.2) and after 8 weeks (Fish oil (N = 86), 95% CI − 14.9 to − 12.0; soybean oil (N = 96), 95% CI − 15.3 to − 12.6). This overlap suggested that there was no significant difference in intervention effect on depressive symptoms between the two study groups