Background: The aim of this study was to investigate whether consumption of Lactobacillus plantarum HEAL 9 (DSM 15312) and Lactobacillus paracasei 8700:2 (DSM 13434) could affect naturally acquired common cold infections in healthy subjects.
Methods: A randomised, parallel, double-blind placebo-controlled study was performed to investigate whether intake of this probiotic mixture could reduce the risk of common cold episodes, number of days with common cold symptoms, frequency and severity of symptoms, and cellular immune response in common cold infections. A total of 272 subjects were supplemented daily with either 10(9) cfu (colony forming units) of probiotics (N = 135) or control (N = 137) for a 12-week period.
Results: The incidence of acquiring one or more common cold episode was reduced from 67% in the control group to 55% in the probiotic group (p < 0.05). Also, the number of days with common cold symptoms were significantly (p < 0.05) reduced from 8.6 days in the control group to 6.2 days, in the probiotic group, during the 12-week period. The total symptom score was reduced during the study period from a mean of 44.4 for the control group to 33.6 for the probiotic group. The reduction in pharyngeal symptoms was significant (p < 0.05). In addition, the proliferation of B lymphocytes was significantly counteracted in the probiotic group (p < 0.05) in comparison with the control group.
Conclusion: In conclusion, intake of the probiotic strains Lactobacillus plantarum HEAL 9 (DSM 15312) and Lactobacillus paracasei 8700:2 (DSM 13434) reduces the risk of acquiring common cold infections.