Research Questions - In children, would natural sources of probiotics (Kefir) compared with supplemental probiotics, reduce incidence of respiratory diseases?

(1) Efficacy of a symbiotic supplementation in the prevention of common winter diseases in children: a randomized, double-blind, placebo-controlled pilot study Ther Adv Respir Dis. 2010 Oct;4(5):271-8. doi: 10.1177/1753465810379010. Epub 2010 Aug 20.

Purpose: To investigate the effectiveness of synbiotic (prebiotic + probiotic) supplementation in reducing common winter diseases (ear, nose, & throat (ENT), respiratory tract or gastrointestinal illness) in children.

Design: The study included children aged 3-7 years who were enrolled in school and were not regularly treated with symbiotic supplementation. This was a randomized, double-blind, placebo controlled study over the winter months. Each child was randomized to either a daily synbiotic or placebo supplementation for 3 months. The synbiotic supplement included Lactobacillus helveticus, Bifidobacterium infantis, Bifidobacterium bifidum, & fructooligosaccharide. Parents were instructed to note any health problem during the study in a diary. Children were examined by the investigator at day 28, 56, and 84 (last day) and diaries were evaluated.

Conclusion: The study concluded that a 3-month symbiotic supplementation decreased risk of occurrence of common winter diseases (ear, nose, & throat (ENT), respiratory tract or gastrointestinal illness) in children and reduced school day loss.

(2) Effect of long term consumption of probiotic milk on infections in children attending day care centres: double blind, randomized trial BMJ. 2001 Jun 2;322(7298):1327.

Purpose: To investigate whether long term consumption of probiotic milk (milk that contains Lactobacillus GG) could reduce gastrointestinal & respiratory infections in children who attended day care centers.

Design: The study included 571 children aged 1-6 years from 18 municipal day care centers in Helsinki, Finland. This was a randomized, double-blind, placebo controlled study over 7 months. The day care staff served the study milk (milk both with and without Lactobacillus GG) three times a day, five days a week. The goal was a daily consumption of 200mL. During the study parents recorded daily symptoms of respiratory of gastrointestinal symptoms as well as absences from school, doctors diagnoses, and prescriptions of antibiotics.

Conclusion: The study concluded that the Lactobacillus group had significantly lower diagnosed respiratory tract infections and had fewer prescribed antibiotics. The Lactobacillus group also had fewer absences from daycare because of illness.

(3) Probiotics for prevention and treatment of respiratory tract infections in children: A systematic review and meta-analysis of randomized controlled trials Medicine (Baltimore). 2016 Aug;95(31):e4509. doi: 10.1097/MD.0000000000004509.

Purpose: To investigate whether probiotic consumption may decrease the incidence of or modify respiratory tract infections in children.

Design: This was a systematic review of randomized controlled trials that compared probiotics to a placebo in children with respiratory tract infections. All studies were double-blind, randomized, and placebo-controlled trials. Electronic databases used were MEDLINE/PubMed, Embase, Cochrane Library, and Web of Science. Eligible probiotic products included single or mix strains at any dose.

Conclusion: The data showed that probiotic supplementation significantly reduced the number of participants with a least 1 respiratory tract infection (RTI) occurrence, had shorter duration of days of RTIs per person, and had fewer number of sick days from school/daycare compared with children who took a placebo.

Summary: In conclusion, I feel all 3 articles had very promising results that supported the use of probiotics in reducing the incidence of respiratory diseases in children. The first two articles used children of similar ages and similar delivery methods (by mixing the probiotic supplement in either water or milk) yet studied different strains of probiotics. Both had positive outcomes with reducing respiratory illness and sick days from school. The third article was very promising because of its extensive data base search, and had the same conclusion as the first 2 articles I studied.

Overall I feel the results half way answered my research question. Unfortunately I wasn't able to find a research article that specifically used Kefir as a probiotic supplement. However, some of the individual probiotic strains that were studied in these research articles are the same strains found in Kefir, so I do believe the use of Kefir would also reduce incidence of respiratory disease in children.