TAMPA (Florida) • Probiotics are a multibillion-dollar international industry, but new research shows that they do not help children recover from stomach flu any better than a placebo.
The results of two randomised clinical trials - which came to the same conclusions - were published in The New England Journal of Medicine on Wednesday.
"Probiotics had no effect on the children," said co-author Phillip Tarr, a professor of paediatrics at Washington University in St Louis, adding that the findings were "not ambiguous". He said: "Parents are better off saving their money and using it to buy more fresh fruit and vegetables for their children."
Probiotics are surging in popularity, with the global market predicted to expand from US$37 billion (S$51 billion) in 2015 to US$64 billion by 2023, according to the report. Five of 12 leading medical groups worldwide endorse their use, as a way to promote gut health by restoring intestinal flora, building up so-called "good bacteria" in children's bodies.
For one study in the United States, researchers tested a popular brand of probiotic, sold under the name Culturelle.
A total of 971 children between three months and four years old were enrolled in the study.
All sought emergency-room care for gastroenteritis - an intestinal condition that can be caused by a virus or a bacterial infection - with symptoms including vomiting and diarrhoea.
The children were randomly assigned to either receive a five-day course of a placebo or Culturelle, which contains the bacterium Lactobacillus rhamnosus GG. A pack of 30, promoted as a "No. 1 paediatrician-recommended daily probiotic", costs around US$20.
But researchers found that kids who took the probiotic showed no difference in the length of illness or the severity of symptoms, compared with kids given a sugar pill.
The second study, carried out in Canada, used a product called Lacidofil Strong, containing Lactobacillus rhamnosus R0011 and L. helveticus R0052. More than 800 children were randomised to receive either a five-day course or a placebo. The difference was so slight, researchers said it was not statistically significant.
The group that received probiotics did not experience less vomiting or diarrhoea, shorter length of illness, fewer follow-up visits to doctors or fewer complications.
"The results deliver a clear message that we need to question the role and benefits of probiotics for other health applications using large, patient-oriented, rigorous clinical trials," said Alberta Health Services paediatric emergency medicine physician Stephen Freedman.