It is well known dietary lactic acid bacteria (LAB) stimulates cell-mediated immunity such as natural killer (NK) activity in mice. Here, we aimed to assay the immunomodulatory effects of a cell preparation of Enterococcus faecalis strain KH-2 (CPEF). We further evaluated the possibility of antitumour activity caused by CPEF administration, because NK cells actively participate in the prevention of tumour formation. NK cell activity and gene expression of IFN-γ and Perforin 1, which were induced most likely by a synergetic action of their cytotoxic activity, were higher in splenocytes of CPEF-administered mice than they were in control mice. Moreover, unlike those of control mice, the splenocytes of CPEF-administered mice had significantly higher CD28⁺CD69⁺/CD4⁺ and CD28⁺CD69⁺/CD8⁺ ratios that resulted in a survival rate with a tendency toward improvement after 47 days of CPEF administration (p=0.1) in Meth-A fibrosarcoma-bearing mice. In conclusion, we showed that CPEF might be effective in treating Meth-A fibrosarcoma in mice, as it helped increase their survival rate via stimulation of an immune response in splenocytes, which involved systemic cellular immunity processes such as cytotoxic activity, and active T cells.

Lactobacillus casei subsp. casei 327 (L. casei 327) was isolated from brown rice. A preliminary study showed that intake of 50 mg of heat-killed L. casei 327 is effective in improving defecation. In this study, we conducted a randomized, double-blind, placebo-controlled, parallel-group trial to investigate the effect of intake of heat-killed L. casei 327 (25 mg: approximately 5 × 10¹⁰ bacteria) on defecation in healthy volunteers with relatively low defecation frequencies. We selected 104 healthy Japanese adults with relatively low defecation frequencies (approximately 3–5 times a week) by screening and pretrial tests. Subjects (n=52 in each group) were randomly given a tablet containing L. casei 327 (group A) or a placebo tablet (group P) daily for 2 weeks. After eliminating data for 9 subjects who met the exclusion criteria for efficacy analysis, data for 95 subjects were analyzed. The defecation frequency and number of defecation days during the intake period and their changes from the pretrial period were significantly higher in group A than in group P. The fecal volume during the intake period was higher in group A than group P, but the difference was not statistically significant. However, the change from the pretrial period was significantly higher in group A than in group P. There were no significant differences between groups in the values of fecal shape, color, odor, and feeling after defecation. These results suggested that intake of L. casei 327 improves defecation in healthy adults who have relatively low defecation frequencies.

Accumulating evidence suggests a relationship between the gut microbiota and the development of obesity, indicating the potential of probiotics as a therapeutic approach. Bifidobacterium breve B-3 has been shown to exert anti-obesity effects in high-fat diet-induced obese mice. In the present study, the anti-obesity effects of the consumption of B. breve B-3 by healthy pre-obese (25 ≤ BMI < 30) adults were investigated in a randomized, double-blind, placebo-controlled trial (trial registration: UMIN-CTR No. 000023919; preregistered on September 2, 2016). Eighty participants were randomized to receive placebo or B. breve B-3 capsules (2 × 10¹⁰ CFU/day) daily for 12 weeks. The visceral fat area significantly increased at weeks 4 and 8 in the placebo group only; no significant change was observed in the B-3 group. Body fat mass and percent body fat were significantly lower in the B-3 group than in the placebo group at weeks 8 and 12 (p<0.05, ANCOVA adjusted with baseline values). Although no significant differences were observed in blood parameters between the groups, the intake of B. breve B-3 slightly decreased triglyceride levels and improved HDL cholesterol from the baseline. No serious adverse effects were noted in either group. These results suggest that the probiotic strain B. breve B-3 has potential as a functional food ingredient to reduce body fat in healthy pre-obese individuals.