Daily intake of fermented milk with Lactobacillus casei strain Shirota reduces the incidence and duration of upper respiratory tract infections in healthy middle-aged office workers

Abstract

PurposeAlthough several studies have demonstrated the efficacy of probiotics for preventing upper respiratory tract infections (URTIs) in at-risk populations, including children and the elderly, few studies have investigated the efficacy of probiotics in healthy adults living normal, everyday lives. Thus, we tried to evaluate the effects of Lactobacillus casei strain Shirota-fermented milk (LcS-FM) on the incidence of URTIs in healthy middle-aged office workers.MethodsIn a randomized controlled trial, 96 eligible male workers aged 30–49 years consumed LcS-FM containing 1.0 × 1011 viable LcS cells or control milk (CM) once daily for 12 weeks during the winter season. URTI episodes were evaluated by a physician via a questionnaire of URTI symptoms.ResultsThe incidence of URTIs during the intervention period was significantly lower in the LcS-FM group than in the CM group (22.4 vs. 53.2 %, P = 0.002). The time-to-event analysis showed that the LcS-FM group had a significantly higher URTI-free rate than the CM group over the test period (log-rank test: χ 2 11.25, P = 0.0008). The cumulative number of URTI episodes and cumulative days with URTI symptoms per person was lower in the LcS-FM group, and the duration per episode was shorter. Inhibition of both reductions in NK cell activity in peripheral blood mononuclear cells and increases in salivary cortisol levels was observed in the LcS-FM group.ConclusionThe results suggest that the daily intake of fermented milk with LcS may reduce the risk of URTIs in healthy middle-aged office workers, probably through modulation of the immune system.

Immune Response of Healthy Adults to the Ingested Probiotic Lactobacillus casei Shirota

“…Our findings have significance for immunosurveillance; for example, NK cells are important in physiological immune surveillance, for example lysis of virally infected cells and tumour cells, and low human NK cell activity has been linked to an increased cancer risk . Furthermore, human studies indicate an association between LcS ingestion and protection against various cancers and upper respiratory tract infections .…”

Effects of yogurt fermented withLactobacillus delbrueckiissp. bulgaricusOLL1073R‐1 on the IgA flow rate of saliva in elderly persons residing in a nursing home: A before‐after non‐randomised intervention study

“…Gleeson et al reported that reduced levels of salivary IgA are associated with increased frequency of URTIs. As people age, they experience a decline in their immune responses; in turn, as the immune defence activities are relatively weak in such populations, they generally experience more infections . In addition, URTI outbreaks easily spread in nursing homes, and elderly people living in nursing homes are hence especially prone to URTIs.…”

Probiotics for the management of type 2 diabetes mellitus: A systematic review and meta-analysis

“…19 billion in 2015 and it is projected to reach USD46.55 billion by 2020; dominated by Asia-Pacific market [11]. The applications of probiotics as alternative biotherapeutics have been successfully demonstrated in treatment of respiratory infection [12], inflammatory bowel disease [13], antibiotic associated diarrhoea [14] and ulcerative colitis [15]. In spite of the booming in vitro and in vivo probiotic studies against metabolic diseases such as T2DM, their application at clinical settings remains scarce [16,17].…”