I was recently disappointed to see a study from Italy in which scientists studied children with severe diarrhea. Probiotics are often prescribed by holistic physicians for treatment of acute diarrhea in children, and I have heard that they often work. In fact, I remember using them for my own son as a small boy.
But it appears that several probiotic products marketed as effective treatments for this problem are not at all effective; scientists have discovered that it seems to depend upon the strain of bacteria that is included in the probiotic supplement.
Probiotics are defined as "micro-organisms that exert beneficial effects on human health when they colonize the bowel." There are a great number of products in this category from supplement suppliers, and in some countries the regulatory agencies allow for very specific labeling. This is the case in Italy.
Researchers at the University of Naples tested five different preparations in 571 children with acute diarrhea. All the children were aged 3-36 months and were visiting a family pediatrician. Children were randomly assigned to receive either a specific probiotic product for five days (intervention groups) or oral rehydration solution (control group). They chose to use a variety of probiotics that were among the best known--those that are available through pharmacies in Italy. However, only two of the five tested preparations showed any effectiveness.
Duration of diarrhea and daily number and consistency of stools were monitored as primary outcomes. Secondary outcomes were duration of vomiting and fever and rate of admission to hospital. Safety and tolerance were also recorded. One strain of bacteria, Lactobacillus GG, worked very well when compared to patients receiving oral rehydration alone, as did a product with a mix of four strains. The three other preparations had no significant effect, however, which suggests that not all commercially available probiotic preparations are effective in children with acute diarrhea.
Several previous studies have shown similar, successful results with the effectiveness of Lactobacillus GG. The other effective preparation contained four bacterial species, two of which have also been shown to protect against diarrhea in chronically sick children.
The authors conclude that the efficacy of probiotic preparations for the treatment of acute diarrhea in children is related to the individual strains of bacteria, and physicians should choose preparations based on effectiveness data. I would add to this that the effectiveness of probiotics has a lot to do with the brand name as well. Buying from a Naturopath, a holistic MD, etc, would likely lead to a better quality product, as it is very difficult to keep organisms alive in tablets sitting on a supermarket or pharmacy shelf over months.