I have personally used probiotics for the last year. I actually started taking them while I was pregnant since there wasnt much else I could take to boost my exhausted immune system.
I got disgustingly sick when I was about 7 months pregnant and a coworker suggested taking probiotics. To my surprise it positively effected everything else including my emotional and mental well being. I looked into the affect of probiotics on depression and was pleasantly surprised. Holistic life is the way to go, screw big pharma!
https://www.salubrainous.com/probiotics-for-depression/
https://www.psychologytoday.com/blog/evolutionary-psychiatry/201602/probiotics-depression