July 1, 2019

expert reaction to study looking at gut bacteria and health in overweight people

Researchers, publishing in Nature Medicine, report that boosting the levels of a specific gut bacteria – Akkermansia muciniphila – may have beneficial health effects for overweight or obese people. 

Prof Ana Valdes, Associate Professor and Reader in Musculoskeletal Genetics, NIHR Nottingham Biomedical Research Centre, University of Nottingham, said:

Does the press release accurately reflect the science?

“The press release talks about “boosting the levels of specific gut bacteria” – what the study shows is that supplementation with specific gut bacteria may have benefits for cardiometabolic health.  Also it would be more accurate to speak of cardiometabolic or metabolic syndrome related traits, not cardiovascular traits which is the term used by the press release.

Is this good quality research?  Are the conclusions backed up by solid data?

“Yes but there are some caveats.  A number of the differences between placebo and treatment 1) are seen only when the bacteria are given pasteurized, not live bacteria.  Although this is in line with what is seen in animal models (pasteurized bacteria having larger effects than live bacteria) essentially there are no effects from live bacteria supplementation and the mechanism by which pasteurized but not live bacteria improve any health parameters appears to be unknown.  2) the differences in insulin parameters  observed are due to the fact that participants in the placebo arm got worse overtime, not really due to an improvement  from baseline in the treatment groups.

How does this work fit with the existing evidence?

“This is a totally novel study.  It is the first time that Akkermansia has been given as a therapy and results are in line with human observational studies and with animal work.

Have the authors accounted for confounders?  Are there important limitations to be aware of?

“Yes, the authors have highlighted most of the limitations, most of which appear to derive from sample size issues.  A much larger study is needed to determine the efficacy and the endpoints need to be clearly defined, possibly via mechanistic studies.  There seem to be strong effects on hepatic function that may require more in-depth phenotyping (e.g. liver MRIs).

What are the implications in the real world?  Is there any overspeculation?

“Although the benefits of probiotic supplementation have been widely investigated, this is, to my knowledge the first time that a bacterial strain identified from microbiome studies has been isolated, cultured and then safely fed to humans.  If the beneficial effects on hepatic function or insulin resistance can be replicated and shown in a more consistent way then it may have important health implications.  It must be noted that there are extensive studies showing dietary benefits for reducing insulin resistance using dietary fibre, which targets the gut microbiomes (see recent Reynolds et al 2019 Lancet systematic review) and also using other probiotics.  In that sense the study adds to the body of evidence of the benefit of targeting the gut microibome to tackle metabolic syndrome.  Also the study did not find significant differences in gut microbiome composition from supplementing Akkermansia to participants.  That suggests that the effects may be due to changes in metabolite production by the microbiome or pathways present (which would require metagenome characterisation of the samples).”

Dr Simon Cork, Lecturer in Medical Education, King’s College London, said:

“This is an interesting study, which adds to our increasing knowledge of the role that gut bacteria play in our every day health.  Gut bacteria are now believed to play a role in various normal and disease functions, from body weight, to depression and Parkinson’s disease.  This study is interesting, as it narrows down the role gut bacteria play to an individual species, although the study is small and so repeating this in a larger cohort will be required before any major conclusions can be drawn.”

* ‘Supplementation with Akkermansia muciniphila in overweight and obese human volunteers: a proof-of-concept exploratory study’ by Clara Depommier et al. was published in Nature Medicine  on Monday 1 July 2019.

DOI: 10.1038/s41591-019-0495-2

Declared interests

Dr Simon Cork: “None.”

None others received.