Intended for healthcare professionals


Effect of long term consumption of probiotic milk on infections in children attending day care centres: double blind, randomised trial

BMJ 2001; 322 doi: (Published 02 June 2001) Cite this as: BMJ 2001;322:1327
  1. Katja Hatakka, research nutritionista,
  2. Erkki Savilahti, professor of pediatricsb,
  3. Antti Pönkä, chief of environmental healthc,
  4. Jukka H Meurman, professor of dental infectious diseasese,
  5. Tuija Poussa, biostatisticiand,
  6. Leena Näse, specialist in clinical dentistryf,
  7. Maija Saxelin, senior microbiologista,
  8. Riitta Korpela, assistant professorg (riitta.korpela{at}
  1. a Valio Research and Development, PO Box 30, FIN-00039 Valio, Helsinki, Finland
  2. b Hospital for Children and Adolescents, Helsinki University Central Hospital, FIN-00029 Helsinki, Finland
  3. c Centre of the Environment, Helsinki City, Helsinginkatu 24, FIN-00530 Helsinki, Finland
  4. d STAT-Consulting, Takojankatu 15 B, FIN-33540 Tampere, Finland
  5. e Department of Oral and Dental Diseases, Helsinki University Hospital, PO Box 263, FIN-00029 HUS, Helsinki, Finland
  6. f Helsinki City Health Department, Kytösuontie 9, FIN-00030 Helsinki, Finland
  7. g Foundation for Nutrition Research, PO Box 30, FIN-00039 Helsinki, Finland
  1. Correspondence to: R Korpela
  • Accepted 14 March 2001


Objective: To examine whether long term consumption of a probiotic milk could reduce gastrointestinal and respiratory infections in children in day care centres.

Design: Randomised, double blind, placebo controlled study over seven months.

Setting: 18 day care centres in Helsinki, Finland.

Participants: 571 healthy children aged 1-6 years: 282 (mean (SD) age 4.6 (1.5) years) in the intervention group and 289 (mean (SD) age 4.4 (1.5) years) in the control group.

Intervention: Milk with or without Lactobacillus GG. Average daily consumption of milk in both groups was 260 ml.

Main outcome measures: Number of days with respiratory and gastrointestinal symptoms, absences from day care because of illness, respiratory tract infections diagnosed by a doctor, and course of antibiotics.

Results: Children in the Lactobacillus group had fewer days of absence from day care because of illness (4.9 (95% confidence interval 4.4 to 5.5) v 5.8 (5.3 to 6.4) days, 16% difference, P=0.03; age adjusted 5.1 (4.6 to 5.6) v 5.7 (5.2 to 6.3) days, 11% difference, P=0.09). There was also a relative reduction of 17% in the number of children suffering from respiratory infections with complications and lower respiratory tract infections (unadjusted absolute % reduction −8.6 (−17.2 to −0.1), P=0.05; age adjusted odds ratio 0.75 (0.52 to 1.09), P=0.13) and a 19% relative reduction in antibiotic treatments for respiratory infection (unadjusted absolute % reduction −9.6 (−18.2 to −1.0), P=0.03; adjusted odds ratio 0.72 (0.50 to 1.03), P=0.08) in the Lactobacillus group.

Conclusions: Lactobacillus GG may reduce respiratory infections and their severity among children in day care. The effects of the probiotic Lactobacillus GG were modest but consistently in the same direction.

What is already known on this topic

What is already known on this topic Children attending day care centres are at high risk of respiratory and gastrointestinal infection

The successful prevention of respiratory infections could be extremely useful for families and for society in general

Short term use of probiotic bacteria has been shown to reduce the severity of rotavirus diarrhoea and the incidence of diarrhoea associated with the use of antibiotics

What this study adds

What this study adds In a double blind, randomised, long term study milk containing Lactobacillus GG slightly reduced the incidence of respiratory infections and antibiotic treatment in children


  • Funding Valio Research and Development, Helsinki, Finland. The University of Helsinki and the City of Helsinki participated in the funding by providing supervision and technical help.

  • Competing interests KH has been employed by Valio Research Centre for two of the past five years. MS and RK are employed by Valio Research Centre. ES has given two educational presentations on Lactobacillus GG for Valio, and TP has received consulting fees from Valio.

  • Accepted 14 March 2001
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