Funded by Synbalance, the research found the probiotic also lowered the prevalence of fever and muscle aches and decreased the need for pharmacological treatment.
The results suggest that probiotics could play a “crucial role” in preventing or reducing the symptoms of upper respiratory tract infections, according to Patrizia Malfa, research and development manager at Synbalance.
“If future research confirms these findings, probiotics could become a recommended intervention for preventing colds or reducing the need for drug treatments—particularly in individuals with weakened immune systems or those prone to frequent infections,” she told NutraIngredients.
Probiotics for immunity
While probiotics are commonly used to improve gut-related disorders, emerging research suggests their benefits may extend beyond gut health.
The use of probiotics as an immunity aid has gained traction in recent years, with Lactobacillus plantarum, Lactobacillus paracasei and Lactobacillus rhamnosus perhaps the best-known for their immune stimulating properties.
Synbalance’s probiotic contains three bacterial strains: Lactiplantibacillus plantarum PBS067, Lactobacillus acidophilus PBS066 and Bifidobacterium animalis BL050.
Each of the bacterial strains was chosen after in vitro screening to assess their strain-specific activity, according to Malfa. Specifically, the strains showed the potential to support anti-inflammatory responses, boost innate immune responses and enhance antioxidant potential.
“We know that the gut plays a fundamental role in modulating the immune response, involving multiple pathways,” she explained. “Primarily, the probiotic strains act by enhancing the activity of the gut-associated lymphoid tissue, a key component in immune function. These strains may modulate the immune response by decreasing the production of pro-inflammatory cytokines and enhancing overall immunomodulatory activity.”
“In addition, they help strengthen the gut barrier, which is essential for preventing harmful pathogens from entering the bloodstream. They may also compete with pathogenic bacteria for nutrients and adhesion sites, thereby reducing the risk of infection,” she added.
Study details
To test the efficacy of the probiotic in a human population, the researchers randomly assigned 65 healthy volunteers to one of two groups. In total, 40 received the probiotic alongside vitamins (B6, B12 and folic acid) and bulking agents, and 25 received placebo (vitamins and bulking agents only).
Cold symptoms and systemic inflammation were assessed at three time points: baseline, post-treatment (12 weeks) and six weeks after treatment (18 weeks).
According to the validated questionnaire (WURSS-21), there was a significant decrease in cold symptoms among the probiotic group compared to the placebo both immediately after treatment and six weeks later.
The probiotic also appeared to reduce the duration of cold symptoms, with participants in the probiotic group experiencing a cold for 4.5% of the study days compared to 6.7% in the placebo group, corresponding to a 32.7% reduction.
The most prevalent cold symptoms (fever and muscle pain) were also assessed. Immediately after treatment, fever was observed in 20% of those who received the probiotic formula compared to 28% in the placebo group. However, this gap narrowed six weeks post-treatment (12.5% in the probiotic group vs 12% in placebo group).
Muscle aches were also reduced, with only 20% of participants in the probiotic group experiencing muscle pain compared to 44% in the placebo group.
Finally, 42.5% of participants in the probiotic group reported no cold symptoms, in contrast to 24% in those who received the placebo. As a result, only 25% in the intervention arm sought treatment compared to 40% in the placebo arm.
“This suggests that probiotics may effectively decrease the need for pharmacological treatment and ease cold symptoms,” the researchers wrote.
Understanding the mechanisms
Overall, the researchers concluded that the blend of bacterial strains appears to alleviate cold symptoms and decrease levels of pro-inflammatory cytokines.
Indeed, while not statistically significant, the pro-inflammatory cytokine IFN-γ decreased in the probiotic group while it increased in the placebo group. However, the probiotic group showed higher IFN-γ levels compared to the placebo group at the beginning of the trial, the researchers noted, which may have influenced this finding.
The authors called for more research to disentangle the probiotic’s mechanism of action in alleviating cold symptoms in healthy individuals.
Source: Nutrients. doi: 10.3390/nu17091490. “Clinical Efficacy of Probiotics for Relieving Cold Symptoms in Healthy Individuals: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial”. Authors: L. Lungaro et al.
