薬理と治療

Abstract

Objective　We examined the immunostimulating effects of food containing sterilized lactic acid bacteria Enterococcus faecalis EC–12（EC–12）on healthy Japanese adults who were aware of their susceptibility to cold. Methods　A computer program randomly and equally assigned the participants（11 in each group）to receive food with EC–12 of 20 mg/day（low–dose EC–12 group）, 200 mg/day（high– dose EC–12 group）, or none（placebo group）. Two capsules were taken daily between meals for four weeks. An immunity test, salivary secretory immunoglobulin A, health–related quality of life（Medical Outcomes Study Short–Form 36–Item Health Survey）, and a physical condition questionnaire were used for assessment. The immunity test assessed overall immunity using the immunity score, which after the 4–week intervention was the primary outcome. Results　The data set per protocol included 11 subjects each in the EC–12 low– and high–dose groups and nine excluding two participants with unreliable data in the placebo group. The immunity scores after four weeks were significantly higher in the EC–12 low–dose than in the placebo group, with a significantly inhibited decreasing T lymphocyte function. Moreover, during the intervention period, the EC–12 low–dose group demonstrated significantly fewer days of nasal discharge and sore throat, while EC–12 high–dose group showed significantly fewer days of coughing than those in placebo group. There were no adverse events attributable to the test foodsʼ consumption. Conclusions　The 4–week EC–12 intervention at 20 mg per day improved the objective immune indices and at 20 mg or 200 mg per day improved the subjective cold–like symptoms in healthy Japanese adults who were aware of their cold susceptibility. Trial registration　UMIN000042294 Foundation　Combi Corporation（Jpn Pharmacol Ther 2023；51：1745‒62）