Probiotics specialist company Probi recently announced the publication of a clinical trial evaluating its immune support formula, Probi Defendum, which found that the beneficial microbes were able to reduce incidences of colds in a sizeable population over three winter months.
 
A randomized, double-blind, placebo-controlled multicenter study enrolled 900 healthy adults, confirming that supplementation with the bacterial strains included in Probi Defendum reduced both episodes of the common cold, as well as recurring colds.
 
“Probi Defendum is now supported by 4 clinical studies, which repeatedly have shown the beneficial effect,” Titti Niskanen, director of Probi’s R&D and Clinical Operations, said. “And in addition, the study provided new data to support the hypothesized mechanism of action, i.e. readying the immune system and supporting a complementary inflammatory response.”
 
“We all know the benefits of a strong and healthy immune system, which has been particularly important this year,” Tom Ronnlund, CEO of Probi, said. “On average, adults suffer from 2-4 episodes of common cold and upper respiratory tract infections per year and children as many as 6-8 yearly episodes, which results in many sick days and absence from daycare and workplaces. With these new data we again show that Probi Defendum can safely be used to support a healthy immune system and its ability to fight the common cold.”

Study Details  
The clinical trial, which was published in the Journal of Nutrition, enrolled 900 people between the ages of 18 and 70 who had contracted at least 4 colds during the 12 months prior to recruitment. The experimental group received Probi Defendum, a combination the strains Lactiplantibacillus plantarum HEAL9 and Lacticaseibacillus paracasei 8700:2 in equal parts, once daily for 12 weeks.
 
The impact of the probiotic on the severity of common colds was the primary endpoint of the trial, however, the researchers didn’t observe any significant differences in terms of severity. However, the researchers noticed significant reductions in cold incidence in the probiotic group, reduced by an average of 1.24 colds, as well as reduced recurrence of colds which was 30% lower than placebo. The use of analgesic was also 18% lower in the probiotic group.
 
Common cold episodes were defined by following three criteria, which had to be met at least two days in a row: answering “yes” to either “do you think you have a cold?” or “do you think you’re coming down with a cold?”; reporting at least one of four common cold symptoms; or scoring at least two points on the Jackson scale, which is used to assess colds. A cold episode also had to be confirmed by an investigator during the episode visit.
 
In an analysis of the participants’ immune markers during cold episodes, the researchers found that the probiotic group had a small but significant increase in the percentage of memory CD8+ cells, as well as a significant difference in the immune markers IFN-y and TNF-a.
 
“The probiotic benefit against infectious diseases can be supported by various mechanisms, either direct, such as competitive exclusion of the infectious agent from mucosal sites, or indirect, such as modulation of the immune response to the infection,” the authors said. They also said that the improved immune response could possibly be attributed to improved phagocytic activity and lymphocytic activity, which could be interpreted as a possible “priming” of the immune system.  
 
The authors also suggested that a study of longer duration, at different dosages, could result in a difference in terms of immunomodulatory capacity which would impact results such as severity and duration of the colds experienced by the adult participants of this trial.
 
“To conclude, L. plantarum HEAL9 and L. paracasei 8700:2 have repeatedly been shown to be well tolerated and to reduce the incidence, duration, and severity of common colds in both adults and children. Existing data indicate that these bacteria may prime the immune system in a protective manner towards future infections of common colds. In the current study, intake of the probiotic product reduced the frequency of recurrent cold infections and resulted in a significantly lower mean number of colds in the participants with colds.”