The effect of Lactobacillus casei on postpartum depression: a randomized controlled trial

The growing evidence of the bidirectional relationship between gut microbial flora and brain neurochemistry and consequently behavior, has recently garnered significant attention as the gut-brain microbial axis. Considering the conflicting results of trials investigating the effects of probiotic therapy on depression, the present study aims to evaluate the impact of Lactobacillus casei on postpartum depression. This randomized controlled trial was conducted on 74 postpartum women admitted to Al-Zahra Hospital, Tabriz, Iran. Eligible women were randomly assigned into the intervention and placebo groups using block randomization method. The intervention group received 500 mg of capsules containing Lactobacillus casei 431 at a dose of 1.5 × 109 cfu/ml once daily, starting the day after delivery and continuing until 21 ± 1 days postpartum. Depression levels were assessed at 5 ± 1, 15 ± 1, and 21 ± 1 days after delivery using independent t-tests and RMANOVA. The mean depression score (SD) at 5 ± 1 days postpartum was 4.7 (2.5) in the probiotic group and 5.6 (2.4) in the placebo group. By 15 ± 1 days postpartum, the scores increased to 9.28 (1.68) in the probiotic group and 11.57 (2.55) in the placebo group. At 21 ± 1 days postpartum, the mean depression scores were 7.39 (2.96) and 8.11 (3.61) in the probiotic and placebo groups, respectively. No significant difference was observed between the groups (Mean Difference: -1.68, 95% CI: 0.08 to -2.56 to, p = 0.71). Lactobacillus casei had no significant effect on alleviating postpartum depression symptoms. Further studies should focus on starting probiotic in pregnant women for a longer duration of use. Iranian Registery of Clinical Trials-Beta vertion, https://irct.behdasht.gov.ir/trial/71775 (IRCT20170506033834N7), registered 2021-08-11.