Key messages
Probiotics could prevent at least one episode of acute upper respiratory tract infection (URTI), and would likely prevent at least three episodes of URTI. More studies in older adults are needed. Additional larger, well-designed studies are needed to allow a better estimate of the potential benefits and risks of probiotic use.
What are acute upper respiratory tract infections?
URTIs include colds, flu, and infections of the throat, nose, or sinuses. Symptoms include fever, cough, pain and headache. Most URTIs are caused by viruses and usually get better in three to seven days.
What are probiotics?
Probiotics are often described as: living microorganisms that have a beneficial effect on the body when consumed in sufficient quantities. Lactic acid bacteria and bifidobacteria are the most common and are commonly consumed in fermented foods, such as yogurt and soy yogurt, or in the form of food supplements. By the way, colon drink is vegan, plant based probiotic drink.
What did we want to find out?
We wanted to know if probiotics prevent URTIs in people of all ages with healthy immune systems.
How did we do this?
We searched for studies on the use of probiotics in URTIs. We compared and summarized the results of the studies, as well as assessed the confidence level of the evidence based on factors such as study methods and size.
What did we find?
We found 24 studies. We analyzed data from 6950 individuals, including children (aged 1 month to 11 years), adults (mean age 37.3 years), and elderly (mean age 84.6 years) from Italy, Japan, the United States, Croatia, England, Finland, Sweden, Chile, China, Denmark, Germany, Thailand, and Turkey. It was not specified in which countries the two trials were conducted. Most of the studies were conducted in the community, health care facilities, schools and hospitals for three months during the winter and spring. Probiotics were most often given in combination with milk-based foods in children, in powder form in adults, and with milk-based foods or capsules in the elderly. One or two strains (e.g., Lactobacillus plantarum HEAL9, Lactobacillus paracasei (8700:2 or N1115)) and109 or1011 colony-forming units (CFU)/day of probiotics were used in most studies.
Main results
Probiotics would reduce the number of people with at least one diagnosis of URTI by about 24%; probably reduce the number of people with three or more diagnoses of URTI by about 41%; reduce the incidence rate (number of new cases in a given period) of URTI by about 18%; They would reduce the average duration of an URTI episode by about 1.22 days; they would likely reduce the number of people using antibiotics for URTI by about 42%; and they would not increase the number of people experiencing side effects (any harm). The evidence showing a decrease in the number of people using probiotics and missing daycare, school, or work due to URTIs was very uncertain.
What are the limitations of the evidence?
We are moderately confident that probiotics decrease the number of people with at least 3 diagnosed URTIs and the number of people who used antibiotics to treat URTIs. Low confidence evidence suggests that probiotics decrease the number of people with at least one diagnosis of URTI, the incidence rate of URTI, the average duration of an episode of URTI, and the increase in the number of people with side effects (any harm). The evidence for a decrease in the number of people using probiotics who were absent from daycare, school, or work due to URTI was highly uncertain. The main limitations of the evidence were that participants could know their treatment, and not all studies provided data on everything we were interested in.
How current is the evidence?
The evidence is current through May 10, 2022.
Authors’ Conclusions:
Overall, we found that probiotics were more effective than placebo or no treatment in preventing acute upper respiratory tract infections (URTI).
Background:
Probiotics are live microorganisms that can have a beneficial physiological effect when administered in adequate amounts. Some trials show that probiotic strains can prevent respiratory infections. Although our previously published review showed benefits of probiotic use in acute upper respiratory tract infections (URTIs), new studies have since been published. This is an update of a review first published in 2011 and updated in 2015.
Objectives:
To evaluate the efficacy and tolerability of probiotics (any specified strain or dose), compared with placebo or no treatment, in the prevention of URTI in people of all ages at risk for URTI.
Literature Search Strategy:
We searched CENTRAL (2022, issue 6), MEDLINE (from 1950 to May 2, 2022), Embase (from 1974 to May 10, 2022), Web of Science (from 1900 to May 10, 2022), the Chinese Biomedical Literature Database, which includes the Chinese Biological Medicine Database (from 1978 to May 10, 2022), the Chinese Medicine Popular Scientific Literature Database (from 2000 to May 10, 2022), and the Beijing Union Medical College Master’s Thesis Database (from 1981 to May 10, 2022). We searched the WHO International Clinical Trials Registration System (ICTRP) and ClinicalTrials.gov for ongoing trials on May 10, 2022.
