Lactococcus cremoris YRC3780 improves subjective stress response in the Uchida-Kraepelin test: a randomized, double-blind, placebo-controlled study

Lactococcus cremoris YRC3780, isolated from kefir, likely improves the hypothalamic–pituitary–adrenal axis response to acute psychological stress by acting on intestinal immune cells and promoting cytokine production. Here we examined the effectiveness of YRC3780 on the stress response in healthy Japanese adults. We investigated the effects of daily YRC3780 intake on the stress response in a randomized, placebo-controlled, double-blind, parallel-group study of 107 healthy Japanese adults (54 in the YRC3780 group and 53 in the placebo group) who had an initial positive Uchida-Kraepelin (U-K) test stress response. After 8 weeks, the POMS2 Total Mood Disturbance (TMD) score after the U-K test and the change in score from baseline score were significantly better in the YRC3780 group than in the placebo. The YRC3780 group showed significant improvements in the POMS2 TMD and in five POMS2 subscores difference before and after the U-K test at 8 weeks. Daily YRC3780 intake significantly improved the stress response in healthy Japanese adults who had an initial stress response in the U-K test. © The Author(s) 2025.