Effects of yogurt fermented with Lactobacillus delbrueckii ssp. bulgaricus OLL1073R‐1 on the IgA flow rate of saliva in elderly persons residing in a nursing home: A before‐after non‐randomised intervention study

Objective The aim of this study was to investigate the alterations in the salivary IgA levels of elderly persons administered yogurt fermented with Lactobacillus delbrueckii ssp. bulgaricus (L. bulgaricus) OLL1073R‐1, which has been reported to reduce the risk of colds. Background Salivary immunoglobulin (Ig)A plays an important role in the defence of the oral cavity mucous membrane against foreign antigens and pathogens. Accordingly, low levels of salivary IgA are associated with an increased risk of upper respiratory tract infection. Furthermore, salivary IgA secretion has been reported to decrease with age. Recently, several studies have reported that certain strains of Lactobacillus and their products can modulate the immune response, but there are currently few studies on the effects of on the IgA level in human saliva. Materials and methods This was a before‐after non‐randomised intervention study. Thirty‐seven elderly persons (mean age, 82.7 years) residing in a single nursing home ingested 112 g of the yogurt every morning for 12 weeks. The participants’ saliva was collected before and after 4, 8 and 12 weeks of yogurt intake. Results Our results showed that yogurt intake affected the concentration of IgA in the saliva (P