Are Probiotics an Effective Treatment for Respiratory Tract Infections?

Review published in advances in nutrition suggest that probiotics “slightly reduce the incidence, duration, and severity of respiratory infections

Respiratory infections, diseases like COVID-19 that lead to infections of the sinuses, throat, airways and lungs are common. They exist on a spectrum from annoyances like a sore throat and cough to potentially life-threatening conditions like pneumonia. Respiratory infections are responsible for more than 2 million deaths worldwide each year.

Despite the high prevalence and burden of disease of respiratory infections, current therapies are limited and often palliative rather than preventive, particularly for the most common infections. Although vaccines are available to prevent certain types of respiratory infections, the development of new vaccines is a long and costly process that often results in products with limited or variable efficacy. Therefore, new and cost-effective strategies to treat a wide range of respiratory infections need to be identified.

In response, authors Julie L. Coleman et al. examined the effects of probiotics, prebiotics, and synbiotics on the incidence, duration, and severity of respiratory infections in adults aged 18 to 65 Non-elderly Adults: A Systematic Review and Meta-analysis,” were published in advances in nutritionthe international review journal of the American Society for Nutrition.

To conduct their research, the authors looked for randomized controlled trials examining the effects of oral probiotics, prebiotics, or synbiotics compared to a placebo. Her research led her to 42 studies that met her criteria, with the majority focusing on probiotics. The studies examined were conducted in 16 countries in Europe, North America, Asia, Australia/Oceania and South America. Study populations included healthy adults, healthy physically active adults, and adults with chronic medical conditions.

According to the authors’ findings, “compared to placebo, orally taken probiotics modestly reduced the incidence, duration, and severity of respiratory infections in non-elderly adults.” Further research showed that these benefits did not vary significantly by species, dose, number of probiotic strains administered, or treatment duration differed.

Due to the lack of studies, the authors could not make any statement about the effects of prebiotic and synbiotic interventions.

Interestingly, the authors noted that “orally taken probiotics may not be or may be less effective in reducing the occurrence, duration, and severity of respiratory infections in physically active populations.” The authors hypothesized that “physically active adults generally also have other lifestyle choices that may reduce the risk of respiratory infections, such as B. a quality diet. Probiotics may not provide additional immune benefits in this context.” On the other hand, high levels of physical activity without adequate rest and recovery can impair immune function and increase the risk of respiratory infection in physically active adults. In any case, more research is needed to determine why physically active populations did not respond as well to probiotics as physically inactive populations.

The authors also found that taking probiotics over fermented milk products may lead to greater reductions in sick days due to respiratory infections. One reason may be related to the fermentation process itself. The authors noted that “lactic acid bacteria used in milk fermentations and as probiotics may increase the bioavailability of immunomodulatory nutrients in milk.”

In conclusion, the authors believe that their systematic review and meta-analysis reinforces the findings of previous studies, which were primarily based on pediatric populations, by “showing that orally taken probiotics also reduce the incidence, duration, and severity of respiratory infections in non-older adult populations.” The authors believe that “replication of positive results for individual probiotic strains and strain combinations in high-quality randomized controlled trials is necessary to conclusively identify the most effective strains and dosing strategies.”