Can probiotics prevent upper respiratory tract infections? Study sheds light

CHINA: Probiotics are probably helpful in avoiding at least three acute upper respiratory tract infections (URTIs), and may help prevent at least one case of acute URTI, states a recent study published in Cochrane Library.

"There is a need for more research on the elderly. To provide more accurate assessments of the advantages and potential drawbacks of probiotic use, larger, well-designed research is required," said the authors.

Probiotics are frequently referred to as live microorganisms that, when taken in sufficient quantities, have positive effects on the body. Lactic acid bacteria and bifidobacteria are the most prevalent kinds in fermented foods like yogurt, soy yogurt, and nutritional supplements.

The study aimed to determine whether probiotics (of any given strain or dosage) are more effective and safer than a placebo or no treatment in preventing acute URTIs in patients of all ages at risk for such infections.

The researchers conducted a meta-analysis of data from 23 trials that included 6950 participants in total, including children (aged one month to 11 years old), adults (mean age 37.3), and senior citizens (mean age 84.6 years).

The major outcomes were the prevalence of URTIs (at least one event and at least three events), the incidence rate (number of cases/person-year), and the average length of each URTI episode. The secondary outcomes included how many individuals used antibiotics for acute URTIs, how many participants missed work or school due to acute URTIs, and how many participants had at least one probiotic-related adverse event. Probiotics were usually given in powder form to adults, more frequently with a milk-based diet to children, and in capsule form to the elderly. 109 or 1011 colony-forming units (CFU) of probiotics per day for longer than three months were utilized in the majority of trials, which used one or two strains (e.g., Lactobacillus Plantarum HEAL9, Lactobacillus paracasei (8700:2 or N1115)).

Conclusive points of the research:

• Probiotics may decrease the number of patients diagnosed with at least one URTI by about 24%, at least three URTIs by about 41%, and the incidence rate (number of new cases over a certain period) of acute URTIs by about 18%.
• Probiotic use may shorten the average number of days that an episode of acute URTIs lasts, lower the number of patients who require antibiotics for URTIs by roughly 42% and possibly prevent an increase in adverse effects (any harm).
• There was conflicting evidence that probiotics reduced the number of persons who missed work, school, or childcare because of acute URTIs (RR 0.14, 95% CI 0.03 to 0.59; 1 study, 80 participants)

The authors concluded that, in terms of preventing acute URTIs, probiotics performed better than a placebo or no treatment.

REFERENCE

Zhao Y, Dong BR, Hao Q. Probiotics for preventing acute upper respiratory tract infections. Cochrane Database of Systematic Reviews 2022, Issue 8. Art. No.: CD006895. DOI: 10.1002/14651858.CD006895.pub4.