Pu F, et al. – Using a randomized, blank–controlled, parallel–group design, the researchers intended to assess whether yogurt supplemented with a probiotic strain could protect middle–aged and elderly people from acute upper respiratory tract infections (URTI). They suggested that yogurt with selected probiotic strains such as Lactobacillus paracasei N1115 (N1115) might lessen the risk of acute upper tract infections in the elderly. In addition, the enhancement of the T–cell–mediated natural immune defense might be one of the important underlying mechanisms for probiotics to express their anti–infective effects.

Methods

• For the purpose of this study, 205 volunteers aged ≥45 years were randomly divided into 2 groups.
• The subjects in the intervention group were orally administered 300 mL/d of yogurt supplemented with a probiotic strain, Lactobacillus paracasei N1115 (N1115), 3.6×107 CFU/mL for twelve weeks.
• On the other hand, those in the control group retained their normal diet without any probiotic supplementation.
• The incidence of URTI was the primary outcome whereas changes in serum protein, immunoglobulins, and the profiles of the T-lymphocyte subsets (total T-cells [CD3⁺], T-helper cells [CD4⁺], and T-cytotoxic-suppressor cells [CD8⁺]) during the intervention were the secondary outcomes.

Results

• Contrasted with the control group, the number of persons diagnosed with an acute URTI and the number of URTI events significantly diminished in the intervention group (P=0.038, P=0.030, respectively).
• It was observed in the findings that the risk of URTI in the intervention group was assessed as 55% of that in the control group (relative risk =0.55, 95% CI: 0.307–0.969).
• Findings revealed that the change in the percentage of CD3+ cells in the intervention group was significantly higher than in the control group (P=0.038).
• The researchers did not find significant differences in the total protein, albumin, globulin, and prealbumin levels in both groups (P>0.05).