Table 2.

Studies about the use of probiotics in respiratory infections

Objective of the study	Study Type	Participants	Results	Location of study	Ref.
Assessment of long term probiotics use on respiratory infection prevention.	Double-Blind, Randomized, Seven months study with placebo control.	571 healthy children (1-6 years)	Lactobacillus rhamnosus GG can decrease respiratory infections and their severity in children.	Helsinki, Finland	[93]
Assessment of Lactobacillus casei Shirota (LcS) in aged subjects with nursing homes stay for reducing respiratory symptoms and enhanced immune response to influenza vaccine.	Double-blind, randomized, placebo-controlled trial.	737 healthy people (age ≥65 years) in 53 nursing homes	No statistically significant effects of probiotics revealed.	Antwerp, Belgium	[94]
Assessment of URTI preventive effects of probiotics (Lactobacillus casei strain Shirota (LcS)) on elder subjects.	double-blinded, randomized, placebo-controlled parallel-group study.	154 elderly subjects	Probiotics reduce acute upper respiratory infection duration.	Tokyo, Japan	[95]
Evaluation of probiotic Lactobacillus casei DN-114001 (fermented product) for prevention of common infectious diseases in elderly.	Multicentric, randomized, double blind and controlled trial.	1072 participants (median age: 76.0 years)	The probiotic reduces both cumulative and episode duration of URTI and rhinopharyngitis. The probiotic was safe and well tolerated.	125 centres in France	[96]
Evaluation of long term probiotic use of Lactobacillus rhamnosus GG (GG) containing milk on respiratory illness.	randomized, double-blind, placebo-controlled trial.	523 children (age: 2-6 years)	Probiotic consumption reduces respiratory illness occurrence, but not in total. Future clinical trial required.	Finland	[97]
Evaluation of Lactobacillus GG (LGG) for prevention of respiratory and gastrointestinal infections in children attending day care centre.	randomized, double-blind, placebo-controlled trial.	281 children	LGG reduces URTI risk and lower the number of respiratory symptoms.	Zagreb, Croatia	[98]
Assessment of Lactobacillus GG (LGG) in prevention of nosocomial infection of gastrointestinal and respiratory at pediatric hospital.	randomized, double-blind, placebo-controlled trial.	742 hospitalized children	Reduced risk of respiratory and gastrointestinal infections among hospitalized children.	Zagreb, Croatia	[99]
Evaluation of prebiotic (galacto-oligosaccharide and polydextrose mixture, 1:1) and probiotic (Lactobacillus rhamnosus GG, ATCC53103) for reducing risk of virus mediated RTI among preterm infants.	randomized, double-blind, placebo-controlled trial.	94 preterm infants (gestational age, ≥32 + 0 and ≤36 + 6 weeks; birth weight, >1500 g)	Reduced incidence of RTI through prebiotics and probiotics.	Turku, Finland	[100]
Evaluation of coadjuvant ability of oral Lactobacillus fermentum (CECT5716) for influenza vaccine.	randomized, double-blinded, placebo-controlled trial.	50 participants (31 ♂ and 19 ♀) with intramuscular influenza vaccine	Increase immune response of influenza vaccine through Th1 response and neutralizing antibodies.	Puleva Food S.A. (Granada, Spain)	[101]
Evaluation of Bifidobacterium longum SP 07/3, Lactobacillus gasseri PA 16/8, B. bifidum MF 20/5 on the severity and incidence of the common cold.	randomized, double-blind, placebo-controlled.	479 healthy adults (18-67 years)	Symptoms and duration of common cold reduces with reduced fever days.	Germany	[102]
Meta-analysis of clinical evaluation of synbiotics on prevention of RTI.	Meta-analysis of randomized control trials.	16/62 studies were used for meta-analysis (including >10,000 individuals)	Synbiotic reduces the incidence of RTI and proportion of RTI experience by participants. This can be an alternative stretagy for preventing RTI.		[103]
Effect of probiotics specially Bifidobacterium and Lactobacillus was evaluated on ARTI.	Meta-analysis of randomized controlled trials.	20 randomized control trials were included	Probiotics use can significantly reduce the number of days of illness, days of absence from daycare/school/work.		[104]
Evaluation of probiotics effects and safety on prevention of URTI in person at risk.	Meta-analysis of randomized controlled trials.	13 trials were included for analysis	Probiotics are beneficial in URTI. It reduces the duration of an episode of URTI and antibiotic prescription rate.		[105]
Evaluation of possible effects of probiotics on RTI associated expenses in USA primary care settings.	Evaluation of two meta-analysis of probiotic use in RTI including YHEC and Cochrane was performed independently.	Meta-analysis of York Health Economic consortium (YHEC) and Chochrane	Probiotics use in USA can save $1.4 billion cost due to ARTI, including ILI ranging from severe flu to mild cold. It also decreases antibiotic use and duration from the absence of work.		[106]