Randomized, Double Blind and Placebo Controlled Study Using a Combination of Two Probiotic Lactobacilli to Alleviate Symptoms and Frequency of Common Cold

Purpose: The efficacy of ProbiDefendum, a combination of the two lactobacilli Lactobacillus plantarum HEAL9 and Lactobacillus paracasei 8700:2, on the severity, duration and frequency of cold episodes was studied in a randomized, double blind, placebo controlled clinical trial. Methods: A total of 310 subjects with increased risk for common cold infection (at least two episodes of common cold during the last six months) were enrolled and were randomly assigned to receive either active product (A-group) or placebo (P-group) over a period of 12 weeks. Subjects reported the occurrence and severity of cold episodes in a diary, scoring 13 different symptoms of common cold over a period of 7 days after the episode began. Results: In the total study population, cold episodes were reported in 148 cases (47.7%). In the A-group, 54 subjects acquired one and 18 subjects acquired 2 episodes whereas 83 subjects had none. In the P-group, 52 subjects reported one, 24 subjects reported 2 episodes and 79 subjects reported none. Although the number of episodes was similar in both groups, cold episodes in the active group were significantly shorter than in the placebo group. The total sum scores of cold symptoms were significantly lower in the active group as compared with the placebo group, as well as in the intention-to-treat (ITT) as in the per-protocol (PP) collectives (ITT: 75.2 ± 40.3 vs. 113.4 ± 66.3; p 0.001; PP: 73.1 ± 38.8 vs. 117.0 ± 66.1; p 0.001). The daily ingestion of the probiotics over a period of 12 weeks was well tolerated. Conclusion: The daily intake of the probiotic dietary supplement ProbiDefendum over a period of 12 weeks efficiently alleviated symptoms of common cold and the duration of cold episodes.