Lactobacillus casei strain Shirota “…may exert beneficial effects preventing the onset of physical symptoms in healthy subjects exposed to stressful situations.”
Lactobacillus helveticus NS8 was compared to the SSRI, citalopram, in rats with depression, anxiety, and cognitive dysfunction due to chronic stress. The probiotic worked better than citalopram in reducing stress-induced anxiety, depression, and cognitive dysfunction. It lowered cortisol and restored serotonin and other brain neurochemical levels to normal.
Other Lactobacillus helveticus-containing probiotics have also been shown to reduce stress-related depression and anxiety by affecting serotonin, cortisol, and other neuroactive compounds in animal studies. For example, Lactobacillus helveticus R0052 combined with Lactobacillus rhamnosus R0011 normalized anxiety-like behavior and learning and memory impairments in immune-deficient rats with HPA-axis dysfunction.