Pasteurized Bacteria for Metabolic Syndrome?
Beware of pilot studies. However, we have a fascinating one for you. Nature Medicine published this study yesterday. It’s a randomized, controlled trial of 32 subjects in three arms. Clara Depommier and colleagues found that a daily supplement of pasteurized bacteria (Akkermansia muciniphila) could improve some of the markers of metabolic syndrome. Specifically, they saw improvements in insulin levels, insulin sensitivity, and total cholesterol in people who took daily doses of this postbiotic. In fact, those changes were statistically significant versus placebo.
A Postbiotic?
Maybe you’re wondering, what is a postbiotic? Simply stated, it is a preparation of byproducts from beneficial bacteria. No live bacteria. In this case it is bacteria (A. muciniphila) inactivated by heat. Although scientists have some evidence postbiotics can have health benefits, they do not understand how. It’s an evolving subject for research.
An Important Microbe for Obesity?
The reason for testing this friendly bug comes from a long line of microbiota research. Muciniphila is less common in the guts of people with obesity and metabolic syndrome. In mice with obesity, it’s helpful. But it’s never been tested in humans. So this pilot study served to show that both live and pasteurized bacteria could be used safely in people with obesity.
Because it was only a pilot study, it didn’t have the power to prove clinical effectiveness. The primary goal was to prove safety. Nonetheless, the researchers saw a significant impact on metabolic end points after just three months. Only with the pasteurized bacteria, though. No effect with the live ones.
Confusion Abounds
Reporting on this study is sowing plenty of confusion. First, we have the challenge of conveying this is only a pilot. The positive results are good news, but not proof that this stuff works. Only 12 subjects received the pasteurized bacteria. In the words of the researchers themselves:
The study was not powered to deliver definitive conclusions on the end points related to metabolic parameters.
And then there’s confusion about a postbiotic. This is a new thing, so health reporters aren’t familiar with it. The live bacteria didn’t work. Only the dead ones. It’s not a prebiotic, either. It’s a preparation of stuff from bacteria that are no longer alive. The mechanism of action is unknown. Full stop.
Thus, we have a fascinating result and more questions than answers.
Click here for the study, here for a commentary, here for the press release, and here for more from the New York Times. For more on postbiotics, click here.
Pasteurized Milk Factory, photograph by the Presidency of the Republic of Turkey / Flickr
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July 2, 2019
July 08, 2019 at 12:58 pm, Moths said:
What is your thoughts on the statistics used to compare changes between groups in this study? And can regression to the mean occur even when differences are not significant (p<0.05) to start? Asking out of genuine curiosity on both of these. I think this was an interesting study and appreciate their carrying it out, but just have some hesitancy around the strength of the conclusions even the authors seem to suggest at some points.
July 08, 2019 at 4:29 pm, Ted said:
After consulting with statistical brainiacs who know more about this that I do, the conclusion is that statistical significance testing is simply inappropriate for a teeny little pilot study. As the authors said, this study simply wasn’t powered to deliver any definitive conclusions about effectiveness. So reporting on p-values only served to muddy the waters.
July 09, 2019 at 2:34 pm, Moths said:
Good to know, thanks! Looking at their original primary outcomes and estimated enrollment on ClinicalTrials.gov, maybe the plan was to have the power to draw some larger conclusions that p-values would be more appropriate for. Again, this is a neat and novel study though!