Culture Techniques Yielding a High Count and High Density of Lactobacillus casei Strain Shirota and Investigation of Novel Health Applications of Gut-brain Interaction: JSNFS Award for Achievement in Technological Research (2020)

Focusing on the beneficial effects of the “Yakult”-exclusive probiotic strain Lactobacillus casei strain Shirota (LcS) on the gut environment, we have been studying new functions of LcS involving the brain-gut axis. In order to maximize the effects of LcS on the brain-gut axis, we have succeeded in increasing the number and concentration of LcS in fermented milk by improving the raw materials and culture techniques. Double-blind, placebo-controlled trials were conducted to examine the effects of this new fermented milk product containing a high count and high density of LcS on psychological and physiological stress responses in healthy medical students under academic examination stress. This revealed that the increased expression of psychological and physical stress markers observed under stress conditions was significantly suppressed in the LcS group relative to the placebo group. In a different trial, daily consumption of LcS maintained sleep quality during the period of increased stress. Based on these results, we have registered the new LcS product as a “Food with Functional Claims”, allowing its functionality to be shown on the package.