Probiotics don’t help ordinary pediatric gastroenteritis

This one isn’t really about critical care but I found it interesting. The over-the-counter sale of probiotics is a huge industry. They are heavily promoted on social media as a cure-all for a wide variety of ills. Probiotics are live cultures of what are often called “good bacteria,” and there are solid physiological reasons for recommending them. But, and this is a huge but, actual clinical data demonstrating their usefulness behind some well-defined disorders is pretty scant. Their potential usefulness in many of the ailments they are touted for is frankly absurd. And, if you’ve looked at them on the store shelf, they’re relatively expensive.

The concept of probiotics is simple. Our intestine, particular our large intestine, or colon, is absolutely stuffed with bacteria. They feed on the rich river of nutrition passing them by and some of them offer us direct benefit in return by synthesizing essential vitamin K, something we can’t do. The overwhelming majority of these bacteria do us no harm at all. In fact, just by being there they do us good by crowding out harmful bacteria. It’s been known for decades anything that disrupts this ratio of good to bad bacteria can be detrimental. Antibiotics, especially oral antibiotics, needed to treat an infection somewhere, such as child with an ear infection, also slaughter gut bacteria indiscriminately along with the offending bacteria at the site of infection. This can lead to problems. The idea of probiotics is to repopulate the gut with good bacteria. There are many preparations that can do this, including yogurt containing live cultures (not all brands do), lactobacillus, and a variety of similar products available over-the-counter. I prescribe probiotics in the PICU when I’m using powerful, broad spectrum IV antibiotics.

I think the role of probiotics in the way I use them in the PICU is reasonably well founded. Using them to help the diarrhea that can be associated with oral antibiotics also makes sense. But do probiotics help in ordinary pediatric gastroenteritis, the so-called “stomach flu” (it has no relation to influenza) which is typically caused by viruses? These patients are not receiving antibiotics. The presumption is that the diarrhea itself somehow disrupts what we call the gut microbiome and that probiotics restore the balance. Two recent studies in the New England Journal of Medicine (here and here) address this question important practical question.

As you would expect from that prestigious journal, the studies are rigorous, placebo-controlled trials. This means subjects were randomly assigned to either the treatment group (which was the probiotic ) or the control group (which was an inert placebo). Neither the families nor the investigators knew which patient was in which group until the code was broken at the end. The subjects of the first study were 971 children 3 months to 4 years of age who came to 1 of 10 emergency departments with acute gastroenteritis — watery diarrhea with or without vomiting. They received a 5 day course of either probiotic or placebo. The second study had 886 children of the same age group, treated for the same time period. The results of both studies showed no improvement in symptoms using the probiotic. This conclusion is pretty compelling because between them they studied 1,857 children. Of course who really knows what was going on in the children’s microbiome, but the bottom line is that adding “good bacteria” didn’t help clinically. Of course this is a different question than if probiotics are helpful for the diarrhea and gas that can be a side effect of antibiotic therapy. For those conditions I think they help. But for ordinary stomach flu, save your money. The articles were accompanied by an editorial, which concludes the same thing. It also gives a good general perspective on what is known about the conditions probiotics help.

If you’re interested in sampling the massive amount being written about probiotics and the microbiome you could try this or this. But beware: people who sell probiotics, and the internet if full of them, will always praise them to the skies for all manner of things. Such claims are often bizarre and violate common sense. It is unknown, for example, if probiotics help normal people who are not ill, or if they ward off intestinal complaints. That is the claim made by some of their more enthusiastic advocates. Or, as the TV commercials put it: “Maintain gut health.” Whatever that means.