Background & aims: The aim of this study was to investigate whether the consumption of Lactobacillus gasseri PA 16/8, Bifidobacterium longum SP 07/3, B. bifidum MF 20/5 (5 x 10(7) cfu/tablet) during at least 3 months influences the severity of symptoms and the incidence and duration of the common cold.
Methods: A randomized, double-blind, placebo-controlled intervention study was performed over at least 3 months during two winter/spring periods. Four hundred and seventy nine healthy adults (aged 18-67) were supplemented daily with vitamins and minerals with or without the probiotic bacteria. Cellular immune parameters were evaluated in a randomly drawn subgroup of 122 volunteers before and after 14 days of supplementation. During common cold episodes, the participants recorded symptoms daily. Stool samples were collected before and after 14 days of probiotic supplementation to quantify fecal Lactobacilli and Bifidobacteria using qRT-PCR.
Results: The total symptom score, the duration of common cold episodes, and days with fever during an episode were lower in the probiotic-treated group than in the control group: 79.3+/-7.4 vs. 102.5+/-12.2 points (P = 0.056), 7.0+/-0.5 vs. 8.9+/-1.0 days (P = 0.045), 0.24+/-0.1 vs. 1.0+/-0.3 days (P = 0.017). A significantly higher enhancement of cytotoxic plus T suppressor cells (CD8+) and a higher enhancement of T helper cells (CD4+) was observed in the probiotic-treated group. Fecal lactobacilli and bifidobacteria increased significantly after probiotic supplementation.
Conclusions: The intake of probiotic bacteria during at least 3 months significantly shortened common cold episodes by almost 2 days and reduced the severity of symptoms.