Effect of ingesting yogurt fermented with <i>Lactobacillus delbrueckii ssp. bulgaricus</i> OLL1073R-1 on influenza virus-bound salivary IgA in elderly residents of nursing homes: a randomized controlled trial

Abstract

<b>Objective:</b> The purpose of this study was to clarify the influence of consuming yogurt fermented with <i>Lactobacillus delbrueckii ssp. bulgaricus</i> OLL1073R-1 (1073R-1-yogurt) on influenza virus-bound salivary immunoglobulin A (IgA) levels, in the elderly residents of nursing homes. <b>Methods:</b> A double-blind, parallel-group, randomized controlled trial was conducted with 96 elderly volunteers residing in 2 nursing homes. During the trial, participants consumed 100 g of 1073R-1-yogurt every morning for 12 weeks, whereas the control participants consumed yogurt fermented with a different <i>Lactobacillus</i> strain (control yogurt). Saliva was collected before the trial and after 4, 8 and 12 weeks of yogurt ingestion. <b>Results:</b> Our data indicated that consumption of 1073R-1-yogurt affected influenza A virus subtype H3N2-bound IgA levels in saliva (<i>p</i> = .001). In addition, saliva flow rate and total IgA levels increased in response to the yogurt intake period in both the 1073R-1 and control yogurt groups (<i>p</i> = .04). <b>Conclusions:</b> Our study suggests that continuous daily ingestion of 1073R-1-yogurt may help prevent infection with influenza A virus subtype H3N2 in elderly subjects with weakened immunity, by increasing the production of influenza A virus subtype of H3N2-bound salivary IgA.