Department of Pediatrics, Chiba University Hospital, Chiba 260-8670, Japan.
Research and Development Division, Kikkoman Corporation, Chiba 278-0037, Japan.
Nutrients. 2020 Jul 3;12(7):1989. doi: 10.3390/nu12071989.
Although some probiotic bacteria have been reported to prevent infections in children, there are few well-designed double-blind studies. Here we evaluated the effects of a probiotic strain of lactic acid bacteria (LAB), K15, on viral respiratory tract infections in preschool children. A four-month, randomized, double-blind, placebo-controlled study was performed in 172 healthy children aged 3 to 6 years. Subjects were administered dextrin alone or dextrin including heat-killed K15 (5 × 10 bacteria). The number of febrile days was the primary outcome. The number of absent days from preschools and the influenza incidence were secondary outcomes. Secretory IgA (sIgA) concentrations in saliva were measured as an exploratory outcome. The primary and secondary outcomes were not significantly different between both groups. Analyses in children with little intake of fermented foods including LAB showed that the duration of a fever significantly decreased by K15 intake. The salivary sIgA level in the K15 group was maintained significantly higher than it was in the placebo group. The effects of K15 on preventing viral respiratory tract infections were not observed without the restriction of fermented foods intake. However, K15 supported anti-infectious immune systems in children who took less fermented foods and the maintenance of salivary sIgA levels in all subjects.
尽管已有研究报道某些益生菌可预防儿童感染，但仅有少数设计良好的双盲研究。在这里，我们评估了一种益生菌（LAB）菌株 K15 对学龄前儿童病毒呼吸道感染的影响。我们进行了一项为期四个月的、随机的、双盲、安慰剂对照研究，共纳入 172 名 3 至 6 岁的健康儿童。受试者随机接受单独的麦芽糊精或包含热灭活 K15（5×10 细菌）的麦芽糊精。主要结局为发热天数。次要结局为缺勤天数和流感发病率。将唾液分泌型免疫球蛋白 A（sIgA）浓度作为探索性结局进行测量。两组主要和次要结局均无显著差异。在摄入包括 LAB 的发酵食品较少的儿童中进行的分析表明，K15 摄入可显著缩短发热持续时间。K15 组的唾液 sIgA 水平明显高于安慰剂组。如果不限制发酵食品的摄入，K15 对预防病毒呼吸道感染的效果并不明显。然而，K15 支持食用较少发酵食品的儿童的抗感染免疫系统，并维持所有受试者的唾液 sIgA 水平。
