A prune extract was separated by an antioxidant-guided assay to obtain an oligomeric proanthocyanidin fraction. The antioxidative oligomer was characterized as a procyanidin oligomer with an average polymerization degree of five and composed of epicatechin and catechin units. The antioxidative activity of the oligomer showed greater potency than chlorogenic acid which is known as an antioxidative component in prunes.

Background: There are various types of sleep disorders, such as insomnia, hypersomnia, and rhythm disorder, which are attributed to diverse and complex background factors. Recently, many studies have reported that lactic acid bacteria, bifidobacteria, and lactoferrin, are related to fatigue and sleep. Considering these factors, we prepared a test food samples containing lactic acid bacteria ingredients (fermentation products, living bacteria, and ground bacteria) derived from the lactic acid bacterium strain Lactobacillus helveticus (LBH_MIKI-020) and theanine, which is known to have a relaxing effect, and subjectively and objectively tested its effects on the quality of sleep.Methods: In this placebo-controlled, double-blinded, randomized crossover study, we randomly selected 40 male and female subjects (aged 20-64 years) to consume for four weeks test food (lactic acid bacteria ingredients –containing) tablets and placebo control food. The physical examination and laboratory test, sleep electroencephalography, Ogri-Shirakawa-Azumi sleep questionnaire (OSA sleep questionnaire), Pittsburgh Sleep Quality Index (PSQI), and Visual Analogue Scale (VAS) questionnaire were measured at during this study period.Results: Sleep electroencephalography: the intergroup comparison in changes until the 4th week showed a significant increase (improvements) compared with placebo control food group. In addition, the sleep efficiency (SE) was compared within the group. In the test food group, the SE increased (improved) significantly in 4 weeks. OSA sleep questionnaire: in intragroup analyses between week 0 and week 4, significant increases (improvements) were found in the test food group. PSQI: in intragroup comparisons between week 0 and week 4, significant decreases (improvements) were found in the test food group. VAS questionnaire: in intragroup comparisons between week 0 and week 4, significant decreases (improvements) were found in the test food group. Conclusion: The sleep efficiency (SE) is improved by continuous consumption of test food (lactic acid bacteria-containing food). Among various sleep disorders, a large population in Japan has trouble with the quality of sleep. Consumption of lactic acid bacteria-containing foods can be a useful means to safely improve the quality of sleep from the viewpoint of self-medication as well. Keywords: lactobacillus helveticus ; lactic acid bacteria; clinical trial; quality of sleep; sleep EEG; OSA sleep questionnaire; PSQI