Abstract
The aim of this systematic review was to present the indirect influence of probiotics on the incidence and duration of acute upper respiratory-tract infections in older people, by regulating the immune system. Eight randomized, placebo-controlled clinical trials met the inclusion criteria, considering the threshold of older people being 60 years and over. Single strain probiotics were used in all studies, including three probiotic strains used in fermented foods: Lactobacillus delbrueckii subsp. bulgaricus OLL1073R-1, Lacticaseibacillus paracasei subsp. paracasei CNCM I-1518 and Lacticaseibacillus paracasei Shirota, and three probiotic strains used as food supplements: Loigolactobacillus coryniformis K8 CECT5711, Bacillus subtilis CU1 and Lacticaseibacillus rhamnosus GG. Current evidence showed that certain probiotic strains were better than a placebo in lowering the incidence or number of older people experiencing acute upper respiratory tract infections; however, not all probiotic strains were efficient, and not all studies reported statistically significant outcomes. More high quality large-scale properly controlled clinical studies focusing on older people are warranted.
Highlights
According to the consensus statement of the International Scientific Association for Probiotics and Prebiotics, probiotics are defined as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host” [1,2,3]
The most common probiotics are members of the Lactobacillus group, which has recently been divided into 25 genera [4], and Bifidobacterium genera (e.g., Bifidobacterium infantis, Bifidobacterium longum and others)
We found that probiotics were better than a placebo in reducing the incidence or risk and duration of acute upper respiratory tract infection (URTI) in older people
Summary
According to the consensus statement of the International Scientific Association for Probiotics and Prebiotics, probiotics are defined as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host” [1,2,3]. The most common probiotics are members of the Lactobacillus group, which has recently been divided into 25 genera [4] Scientific evidence of probiotic benefits on human health is continuously expanding, and there are enough data to justify investigation of probiotics for treatment or prevention of several disorders, from antibiotic and Clostridium difficile-associated diarrhea, irritable bowel syndrome and inflammatory bowel disease, to anxiety, depression and wound healing [6,7,8,9,10] Another consensus statement of the International Scientific Association for Probiotics and Prebiotics reported the definition of fermented foods as “foods made through desired microbial growth and enzymatic conversions of food components” [11]. Fermented foods have been consumed for thousands of years, they have been receiving increased attention among biologists, nutritionists, technologists, clinicians and consumers, as research has shown that fermented foods could improve gastrointestinal and systemic
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