A big, successful trial of probiotics

Not a GI specialist here, but I've read plenty of randomized controlled trials. The one-liner here might be "high quality[1] study shows substantial reduction in infant infections in rural India[2]." The biological mechanism makes sense, and as discussed in the article could be more than just good bacteria fighting off bad bacteria. A cynic may say the immunomodulation stuff is kind of hand-wavy and not being a GI specialist, pediatrician or immunologist myself I don't know. That would be an important point because all infections were reduced (not just GI infections), which may point to confounding variables. More on that later.

[2] As far as how the study applies to most of Europe and the US where infant mortality is 10x less, hard to say. The number of infants needed to treat to prevent a single infection was 27 which is low assuming these drugs are cheap and without side effects. Immediate side effects are unlikely given the low and comparable drop out rates among control and treatment groups. However, long-term effects are unknown given the timeframe of the study. Forming a recommendation for countries with more rigorous pasteurization/food preparation/etc, perhaps more access to care and well-child checkups, and much lower infant mortality in general isn't particularly easy here. I'm not up to date on other studies with probiotics. Again, not my specialty.

[1] The study quality looks sound and exclusions were reasonable, the control (placebo) and treatment groups matched up well in many ways and were sizable. There wasn't very much in the way of dropouts. The study looked at too small a population to determine differences in infant deaths, if there is one at all.

Access to clean water...

Pediatric MD PhD. These are exciting results.

Sepsis among neonates is a major concern, even in the developed world. Babies new to the world have very weak immune systems, particularly with regard to antibody response which is initially almost entirely composed of waning amounts of transplacental IgA. This paper points out the the developing world has even higher rates of infant mortality from bacterial sepsis. So this is a big problem and impactful solutions have been tough to come by.

This is a large double-blind placebo controlled trial. They gave eligible babies 7 consecutive daily doses of either placebo or the study agent. Table 1 shows that both study groups are very similar, so we should not be too concerned with confounding variables. Table 2 shows the striking data re: sepsis death rates, with this "synbiotic" (probiotic bacteria + bacterial food) reducing death from sepsis by almost half(!). Table 3 looks at all causes of death and importantly, significant differences in other causes of death were not observed between the two groups--it wouldn't be all that helpful if this synbiotic group seemed to get some other serious problem as a side effect. It is a pretty straight-forward study and no major flaws in their methods or conclusions jump out at me.

While exciting overall, the authors point out some important points at the end. I think the most interesting is that they used this particular species of lactobacillus after studying babies in India about 20 years ago and finding differences in the rates of colonization with this and other probiotic species. In other words, they didn't just throw any sort of "good bacteria" at these babies--they had strong evidence to show that it actually colonized them and therefore could , in theory, have an effect on rates of sepsis. If they had used lactobacillus GG (one of the other species that they found had low rates of colonization), it would stand to reason that they wouldn't have gotten such an impressive effect or maybe none at all. Then the media would say, "probiotics don't save babies from sepsis." Basically I'm just applauding their careful selection of this bacterial species.

One final important note is that this result should not be generalized to other populations without future studies showing similar effects. The gut microbiome is influenced by geography and other environmental factors and interacts heavily with out immune systems, large parts of which vary by genetic background. To put it another way, just because this bacterial species works well in rural India does not mean it will work well in Peru or anywhere else.

My issue isn't on the faith in probiotics side...the problem is which ones do I buy.

It's near impossible to know you're getting the good stuff so to speak.